Karen Burns Podiatry in Boolaroo, New South Wales, Australia | Podiatrist

Karen Burns Podiatry

Locality: Boolaroo, New South Wales, Australia

Phone: +61 2 4958 5694

Address: 58 Main Road 2284 Boolaroo, NSW, Australia

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23.01.2022 Demonstration of Neutral Suspension Negative Casting Technique The neutral suspension casting technique was first described by Root et al as a method to obtain ...a three-dimensional impression (i.e. negative cast) of the plantar aspect of a patient's foot. The foot is held with the subtalar joint neutral and with the lateral column of the foot dorsiflexed against resistance (Root ML, Weed JH, Orien WP: Neutral Position Casting Techniques, Clinical Biomechanics Corp., Los Angeles, 1971). The resulting negative cast, made from two 5" x 30" extra-fast setting plaster splints, is then used by the custom-foot orthosis laboratory to make three-dimensional positive casts of the patient's foot by pouring plaster into the negative casts. More recently, most custom foot orthosis laboratories are now scanning the inside of the casts to create a three-dimensional digital file from which custom foot orthosis may be fabricated. I do not cast every patient in exactly the same way shown in this video. Rather, I may use slight positional variations within the joints of the foot during negative casting for some patients in order to alter the three-dimensional morphology of the plantar foot. These variations in negative casting technique allow the treating clinician to slightly vary the three-dimensional shape of the negative cast from one patient to another in order to optimize the biomechanical function of custom foot orthoses for their patients.

21.01.2022 Low-Dye Strapping for Plantar Fasciitis and Plantar Arch Pain Here I am demonstrating the proper technique for application of Low-Dye strapping. Typical low-Dye... strapping involves using 1" and 2" cloth adhesive tape to apply a tension-load-bearing strapping system to the plantar longitudinal arch of the foot. Low-Dye strapping, by preventing excessive longitudinal arch flattening, reduces the tension force within the plantar fascia and other plantar tension load-bearing structures of the plantar foot, such as the plantar intrinsic muscles and plantar ligaments. Low-Dye strapping may be used in conjunction with custom foot orthoses to decrease the pain with weightbearing activities within the tension load-bearing structures of the plantar foot. The 1" and 2" cloth adhesive tape I like to use for Low-Dye strapping is Johnson & Johnson Zonas porous tape. https://www.amazon.com/Johnson-JJ5104-Zonas-P//ref=sr_1_4 https://www.amazon.com/Johnson-First-Aid-Zona//ref=sr_1_2 Ideally, the skin of the plantar foot should be cleaned with isopropyl alcohol before taping to increase tape adhesion. In addition, a "pre-tape spray" containing a skin adherent greatly helps the tape stay adhered tightly to the skin for a longer period of time. https://www.amazon.com/Cramer-Taping-Spray-A//ref=sr_1_10 Alternatively, K-tape, a more expensive alternative to cloth adhesive tape, which is more compliant (i.e. more stretchy) than cloth adhesive tape, can also be used in the same fashion and is generally easier for the patient to apply. However, K-tape will generally produce a lesser effect on reducing the tension load on the plantar fascia and other tension load-bearing structures of the longitudinal arch than with cloth adhesive tape (Kirby KA: Longitudinal arch load-sharing system of the foot. Revista Española de Podología, 28(2), 2017) https://www.sciencedirect.com//artic/pii/S0210123817300087

20.01.2022 Abductory Twist: What is It and Why Does It Occur? Abductory twist is a sudden abduction motion of the foot at the time of heel-off during walking gait. Abduct...ory twist is a relatively common gait abnormality that occurs due to the external rotation motion of the pelvis above the foot during late midstance not being matched by corresponding subtalar joint supination and tibial external rotation during late midstance. As a result of this "mismatching" of transverse plane rotations of the pelvis and lower extremity during late midstance, the resultant increase in elastic strain energy occurring within the muscles, tendons and ligaments of the hip, knee and lower extremity will be resolved into this rapid medial movement of the heel at the time of heel-off. The reason why the abductory twist occurs just after the instant of heel-off is because the frictional forces between the heel of the foot and the ground are no longer present after heel-off to prevent external rotation motion of the foot relative to the ground. The best example of an abductory twist is seen in the last few steps of the left foot of this slow motion video. It is often commonly clinically seen with late midstance pronation which makes good biomechanical sense because increased subtalar joint pronation moments in late midstance will tend to result in both late midstance pronation and abductory twist.

19.01.2022 Gait Characteristics of Cavus Feet with Laterally Deviated Subtalar Joint Axes Feet with pes cavus deformity, more often than not, have lateral deviation of the... subtalar joint (STJ) axis. This lateral deviation of the STJ axis creates excessive external STJ supination moments which can be seen during gait as excessive supination of the foot in this video. Since the medial calcaneal tubercle is so far medial to the STJ axis during heel contact in this foot, this medial positioning of the plantar heel in this patient with cavus feet creates excessively large magnitudes of external STJ supination moment generated from ground reaction force (GRF) acting on the plantar calcaneus during the contact phase of walking gait. These large magnitudes of external STJ supination moment at ground contact of the calcaneus in these feet cause the STJ to rapidly supinate in the early stance phase of gait. In this individual, also note the shortened stride length which is likely due to the lateral ankle instability being caused by these excessive STJ supination moments. When the central nervous system (CNS) notes these excessive STJ supination moments during late midstance, the CNS likely does not fully activate the gastrocnemius and soleus during the late midstance phase of walking since full contractile activity of the gastrocnemius and soleus would increase the internal STJ supination moment (i.e. due to the Achilles tendon inserting well medial to the STJ axis on the posterior calcaneus) which would, in turn, cause even more lateral ankle instability and possibly an inversion ankle injury. Careful visual gait examination is the key to the optimum treatment of mechanically-based pathologies of the foot and lower extremity. Visual gait examination is a skill which should be practiced daily by podiatrists and other foot-health professionals in their clinics.

18.01.2022 Medial Heel Skive Orthoses and Posterior Tibial Tendon Dysfunction All patients with posterior tibial tendon dysfunction (PTTD) have medially deviated subtalar ...joint (STJ) axes. [The illustration shows a frontal plane cross-section of a right foot with PTTD in a hiking boot with a medial heel skive foot orthosis.] A medially deviated STJ axis simply means that the STJ axis spatial location is more medially translated and adducted than normal so that ground reaction force (GRF) will then cause increased magnitudes of external STJ pronation moments during weightbearing activities. In order to effectively treat more significant cases of PTTD conservatively, a combination of very specific orthosis design modifications are necessary to achieve optimal treatment of this disabling condition. First of all, a foot orthosis with a deep heel cup and a medial heel skive is necessary to shift orthosis reaction force (ORF) more medial on the plantar heel which will increase the magnitude of external STJ supination moment (Kirby KA: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992). In addition, the orthosis should have a well-formed and stiff medial longitudinal arch to help shift ORF more medial on the plantar midfoot which will also increase the magnitude of external STJ supination moment. Finally, a hiking boot or high top shoe can also add significant magnitudes of external STJ moment by creating a force couple where the lateral heel of the boot heel counter creates a medially directed force vector on the lateral plantar calcaneus and the medial upper of the boot creates a laterally directed force vector on the medial malleolus. The combination of these two oppositely directed force vectors from the boot create a powerful external STJ supination moment that will act synergistically with a medial heel skive foot orthosis to increase the magnitude of external STJ supination moment which will, in turn, decrease the tension stress on the posterior tibial tendon during weightbearing activities. The most likely explanation for decreased posterior tibial tendon tension force is due to the central nervous system decreasing the efferent output to the posterior tibial muscle when the medial heel skive orthosis and boot are being worn. In turn, posterior tibial contractile activity is decreased and posterior tibial tension force is decreased during gait. One important point to remember is that foot orthoses cause change in STJ moments by alterations of GRF acting only on the plantar foot. This means that since the foot orthosis only acts on the plantar foot inferior to the STJ axis, it can generate external STJ supination moments only by altering the GRF on the plantar foot. On the other hand, a high top boot, or Arizona brace for that matter, all have the ability to exert direct mechanical effects both inferior and superior to the STJ axis. As a result of their ability to "span the STJ axis", high top boots and braces all have a very significant mechanical potential to generate additional external STJ moments across the STJ axis. The end result of these time-tested methods of using medial heel skive foot orthosis and hiking boots in the treatment of patients with PTTD is that they nearly always report that they can immediately ambulate with much less pain. In addition, over time, these patients can often avoid foot surgery and show significant healing from their PTTD when expertly designed foot orthoses and other conservative therapeutic measures are employed for their disabling condition (Kirby KA: Conservative treatment of posterior tibial dysfunction. Podiatry Management, 19:73-82, 2000).

17.01.2022 Foot Orthosis Modifications for Plantar Plate Tears Tears of the plantar plates of the lesser metatarsophalangeal joints (MPJ) can be effectively treated with c...ustom foot orthoses which are specially modified to reduce both the compression and tension forces on the affected plantar plate. These orthoses are designed using Tissue Stress Theory where the goal of foot orthoses are to reduce the excessive loading forces on the injured structural component of the foot. The Subtalar Joint Neutral Theory, taught by Root and colleagues for decades, emphasized "preventing compensations for deformities of the foot" and "trying to make the foot function in the subtalar joint neutral position". Unfortunately, Subtalar Joint Neutral Theory neglected to stress the importance of using forefoot extensions in orthoses and was not effective at treating plantar plate tears, but rather focused more on attempting to get the foot to function in subtalar joint neutral position. Over the years of treating plantar plate tears (previously called MPJ capsulitis), I have used a number of orthosis modifications, two of which are shown below (see my illustrations below for 2nd MPJ plantar plate tears). The anterior edge of the plate can be modified to create an extended portion just proximal to the 2nd metatarsal head in order to support the 2nd metatarsal shaft distally all the way to the metatarsal neck. Alternatively, a metatarsal pad may be added to the anterior edge of the orthosis. In addition, it is very important to accommodate the affected metatarsal head with a flexible, non-compressible material such as Korex or ethylene vinyl acetate (EVA). I generally will start with 1/8" (3 mm) Korex which may be increased, or decreased, in thickness depending on the patient's symptomatic response to the forefoot accommodation. Such orthosis modifications can mean the difference between pain with each step versus no pain at all during the day for the patient suffering from plantar forefoot pain from plantar plate tears. I will combine foot orthoses with other conservative therapies such as daily to twice-daily plantar icing therapy, having the patient purchase soft-soled sandals for home use (Oofos sandals are my favorite), avoiding any barefoot weightbearing activities, and using digital plantarflexion taping to prevent excessive plantar plate tension forces during gait. Cortisone injections may also be administered into the soft tissues plantar to the plantar plate to reduce excessive inflammation and swelling if the patient's foot does not respond to other conservative measures after a few weeks of treatment. In addition, in more severe cases of 2nd MPJ plantar plate tears, a cam-walker boot with a cut-out under the 2nd metatarsal head, may be used for 2-4 weeks to reduce inflammation and pain at the affected joint.

15.01.2022 Verrucae Plantaris Needling Technique in 17 Year-old Male Patient Demonstrated here is the Falknor needling technique for eradication of verruca plantaris lesio...ns. American podiatrist, Gordon Falknor, DPM, first described this procedure 51 years ago, in February 1969 (Falknor GW: Needling-a new technique in verruca therapy: a case report. JAPA, 59:51-52, 1969). I have been using the Falknor needling technique for verrucae plantaris lesions for the past 25 years. During that time, my success rate in eradicating these lesions with this technique is approximately 80%. No infections or other untoward complications have ever been noted using this procedure. In my performance of the Falknor needling technique in this 17 year-old male patient, I used 3.0 ml of local anesthetic to infiltrate deep to the lesion with a 5.0 cc syringe and 25 gauge needle. About 5 seconds of ethyl chloride spray was used prior to the needle stick at the needle injection site to temporarily numb the area of injection. I rarely use a posterior tibial nerve block when performing these plantar injections since there is only mild pain from plantar injection after transient skin freezing with the ethyl chloride spray. After local anesthetic administation, the area of the verrucae is prepped with a povidone-iodine solution and the area is draped with a sterile fenestrated drape. Next, using a 25 gauge needle, the verrucae plantaris lesion is punctured through the full thickness of the epidermis and dermis until bleeding occurs. About 100 needle punctures were used in this lesion. For larger verruca lesions, more needle punctures should be used. For smaller verruca lesions, fewer needle punctures will be necessary. The depth of penetration of the needle needs to be such that the tip of the needle passes through the dermis and into the subcutaneous fat so that perceptible bleeding occurs at the needle puncture site. The clinician will initially feel needle resistance once the needle first pushes through the epidermis and dermis. Once the subcutaneous fat is entered with the needle tip, there will be a sudden decrease in resistance to needle advancement which is where needle advancement into the skin should be stopped. There is no need to go deeper than the subcutaneous fat with needle puncture to stimulate the immune response required to cause eradication of the verruca lesion using the Falknor needling procedure. The basic idea is to drive the verruca virus into the subcutaneous fat and blood stream of the patient so that the patient's immune system will "recognize" the virus, stimulate an immune response, and rid the body of the verruca lesion over time. The Falknor's needling technique is a classic example of an auto-innoculation procedure which has been used for years within the medical profession. The Falknor's needling technique is especially effective for mosaic verrucae since only a few of the larger lesions (i.e. "mother lesions") need to be needled to have all of the verrucae lesions of the mosaic verrucae to be eradicated from the plantar foot generally with 3-4 weeks of the needling procedure. Using the Falknor needling technique on these hard-to-heal mosaic verrucae will make you a "hero" in the patient's eyes since the clinical results are, simply, quite amazing. Simple bandaging of the needling site is done with sterile gauze and adhesive wrap (i.e. Coban). The patient can remove the dressing 2-3 hours after the procedure, wash the needling site with soap and water, and then apply a bandaid to the area. Normal weightbeaing activities can be resumed the next day with the bandaid on the foot for one to two days. The Falknor needling technique is my favorite verrucae eradication procedure since it works better than any others I have used over the past 35 years of practice, takes only about 20 minutes of time to accomplish in my office (including injection, prepping, draping and bandaging) and causes a minimum of post-procedure pain. For example, the children I have performed this procedure on are running and playing soccer the next day on their operated foot with a minimum of pain. All podiatrists should learn to use this procedure for the good of their patients and their practices.

14.01.2022 Just had a short article on plantar fat pad atrophy published in the July 2020 issue of Podiatry Today magazine. I believe plantar fat atrophy is often over-looked as an etiology of plantar heel and plantar forefoot pain.

13.01.2022 The Windlass and Reverse Windlass Effects of Hicks The Windlass and Reverse Windlass Effects were first described 66 years ago by John H. Hicks in his classic p...aper on the biomechanics of the plantar fascia in 1954 (Hicks JH: The mechanics of the foot. II. The plantar aponeurosis and the arch. J Anatomy. 88:24-31, 1954). Hicks noted that hallux dorsiflexion, in both live feet and cadaver feet, produced the mechanical effect of raising of the medial longitudinal arch and plantarflexing the first ray. He also found that during relaxed bipedal standing, hallux dorsiflexion produced subtalar joint supination and external rotation of the leg. Hicks called this mechanical linking of hallux dorsiflexion to first ray plantarflexion, medial longitudinal arch elevation, subtalar joint supination and external leg rotation the "Windlass Effect". Hicks described in his paper how the hallux and the plantar fascia were a mechanical analogue to a windlass winding a cable (i.e. plantar fascia) around the drum (i.e. first metatarsal head) of the windlass. Hicks also noted that a "Reverse Windlass Effect" occurred in both live and cadaver feet where the digits all plantarflexed with the application of loading force being applied onto the plantar metatarsal heads. Hicks determined that the "Reverse Windlass" was due to the plantar loading force on the metatarsal heads producing a flattening and lengthening of the longitudinal arch of the foot which, in turn, increased the tension within the plantar fascia and plantarflexion of the digits. Hicks also noted that cutting of the plantar fascia in cadaver feet eliminated both the Windlass and Reverse Windlass Effects. Podiatrists and foot-health clinicians should understand the windlass and reverse windlass effects that Hicks described 66 years ago since the plantar aponeurosis has very important biomechanical functions for the human foot during weightbearing activities. Plantar fascial ruptures and plantar fasciotomies will alter the function of the plantar fascia and cause a multitude of pathological conditions as a result of the alterations within the biomechanical function of the plantar fascia. For those who would like to further reading on the biomechanical functions of the plantar fascia, I wrote an article on the 10 functions of the plantar fascia six years ago which is listed below. https://www.podiatrytoday.com/understanding-ten-key-biomech.

08.01.2022 Medial Heel Skive Orthoses Found to Help Patellofemoral Syndrome The Medial Heel Skive Orthosis Technique was first published in the podiatric medical literatur...e in 1992 after I had invented and started using the technique in about 1989 (Kirby KA: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992). The Medial Heel Skive Orthosis Technique has been used in a study of foot orthosis treatment of patellofemoral syndrome first published in 2017. Custom foot orthoses with medial heel skive modifications were used in 14 patients with patellofemoral syndrome and found to improve knee symptoms. Data analyses indicated significant (P=0.008) improvements in weight bearing pain after 4 weeks of using the orthosis with the medial heel skive technique (Bahramian F, Aminian G, Bagherzadeh M, Fardipoor S, Kashani V. The Effect of Custom Made Foot Orthoses Fabricated With Medial Heel Skive Technique on Pain and Function in Individuals With Patellofemoral Pain Syndrome. Iranian Rehabilitation Journal. 2017; 15(1):37-42). The Medial Heel Skive Technique is a powerful addition to the orthosis modifications the podiatrist and foot-health clinician can use to treat their patients with pronation-related pathologies. Understanding the function of the Medial Heel Skive Orthosis Technique is critical to achieving the best results with custom foot orthoses.

08.01.2022 How Does the Plantar Fascia Help Increase Longitudinal Arch Stiffness During Midstance and Propulsion? John Hicks, an orthopedic surgeon from Birmingham, UK, wa...s the first scientist to write extensively on the biomechanical functions of the plantar fascia (i.e. central component of the plantar aponeurosis) over 65 years ago (Hicks JH: The mechanics of the foot. II. The plantar aponeurosis and the arch. J Anatomy. 88:24-31, 1954). He noted that, in both live feet and in non-living cadaver feet, if hallux dorsiflexion occurred, that longitudinal arch raising would occur, which he called the "Windlass Effect". Hicks also described the "Reverse Windlass Effect" where longitudinal arch lowering during weightbearing would cause the digits to plantarflex. In the summary of his experimental work on the plantar fascia, HIcks noted three key points: "1. The plantar aponeurosis at its distal end is attached through the plantar pads of the metatarsophalangeal joints to the proximal phalanges. The attachment is mechanically very strong. 2. When the toes are extended they pull the plantar pads and hence the aponeurosis forward around the heads of the metatarsals, like a cable being wound on to a windlass. The arch is caused to rise because the distance between the metatarsal heads and the calcaneum is thereby shortened. 3. The toes are forced into an extended position in toe-standing and walking by the action of body weight, and the arch is caused to rise by this ligamentous mechanism without the direct action of any muscle." This classic paper by HIcks is a must-read for anyone with an interest in foot and lower extremity biomechanics (Hicks JH, 1954). Since the time of HIcks, other podiatrists have noted the importance of the function of the plantar fascia during walking. Howard Dananberg, DPM, in his classic papers on functional hallux limitus, discussed the windlass effect and plantar fascial function when describing three "auto-supportive mechanisms" in the human foot during walking including: 1) Calcaneocuboid joint locking, 2) Truss and locking wedge effect, and 3) Windlass effect (Dananberg HJ: Gait style as an etiology to chronic postural pain. Part I. Functional hallux limitus. JAPMA, 83:433-441, 1993). In his description of the calcaneocuboid joint locking mechanism of Bosjen-Moller from 1979 (Bojsen-Møller , F: Calcaneo-cuboid joint and stability of the longitudinal arch of the foot at high and low gear push off. J Anat, 129:165, 1979), Dananberg noted the following important characteristics of the plantar fascia: "The plantar aponeurosis runs from the inferior surface of the calcaneus to the bases of the proximal phalanges of the toes. It is thickest at the first toe and progressively thinner toward the fifth toe. The tension that develops within this fascia dictates the stability it provides to the foot. This action is that of a tension band. The plantar aponeurosis can be likened to a string on a bow (bow and arrow). When sufficient tension is evident within the string, the bow maintains its arched shape. When cut, the bow will immediately straighten. The mechanism of the developing adequate tension within the aponeurosis at the correct time is essential for proper foot function. If the tension is produced too soon, the foot will not provide proper mobility at impact. If the tension is produced too late, the foot will not have adequate stability to handle the increasing force applied to it during the mid-to-late phase of single-limb support" (Dananberg, 1993). In 2017, I also published a paper on longitudinal arch biomechanics and plantar fascia function in the Spanish podiatry journal, Revista Española de Podología, My paper on the Longitudinal Arch Load-Sharing System (LALSS) of the Foot described how four sets of tension load-bearing elements in the plantar foot all worked together to stiffen the longitudinal arch (Kirby KA: Longitudinal arch load-sharing system of the foot. Revista Española de Podología, 28(2), 2017). From superficial to deep (i.e more plantar to more dorsal) these four sets of tension load-bearing elements are the 1) plantar fascia, 2) plantar intrinsic muscles, 3) deep posterior compartment muscles (i.e. posterior tibial, flexor digitorum longus and flexor hallucis longus) and peroneus longus muscle, and 4) the plantar ligaments. The passive elements of the LALSS, the plantar fascia and plantar ligaments, work independent of the central nervous system (CNS). The active elements of the LALSS, the plantar extrinsic and plantar intrinsic muscles, are actively controlled by the CNS (Kirby, 2017). The passive elements of the LALSS, the plantar ligaments and plantar fascia, provide a baseline level of longitudinal arch stiffness which requires no metabolic cost to the individual since tension within the plantar ligaments and plantar fascia increases without muscular effort as the longitudinal arch flattens and lengthens during weightbearing activities. The passive elements of the LALSS are assisted by the active elements of the LALSS, the extrinsic muscles of the plantar arch and plantar intrinsic muscles, which are under direct control of the CNS. The extrinsic muscles of the plantar arch and plantar intrinsic muscles function to increase the stiffness of the longitudinal arch above the baseline longitudinal arch stiffness provided by the passive tension within the plantar fascia and plantar ligaments during weightbearing activities. Together both the passive and active elements of the LALSS work synergistically to modulate the magnitude of longitudinal arch stiffness depending on the nature, intensity and direction of the weightbearing activity chosen by the individual (Kirby, 2017). In other words, all four sets of these tension load-bearing elements work together with each other to increase the stiffness of the longitudinal arch not only during midstance, but also during propulsion (see illustration below). Contrary to claims from recent research, there is no evidence that the plantar intrinsic muscles and deep posterior compartment and peroneus longus provide any more increase in longitudinal arch stiffness than that of the plantar fascia and plantar ligaments. In fact, each one of these tension load-bearing elements assist the other three elements which make up the LALSS to allow normal walking gait to occur, which specifically includes longitudinal arch stiffness during the second half of the stance phase of walking gait (Kirby, 2017). In fact, finite element modelling studies of the plantar fascia, longitudinal arch and windlass effect have demonstrated that plantar fascia tension increases 66% due to the windlass effect during propulsion which, by itself, increasea the longitudinal arch stiffness during propulsion (Chen YN, Chang CW, Li CT, Chang CH, Lin CF. Finite element analysis of plantar fascia during walking: a quasi-static simulation. Foot & ankle international. 2015 Jan;36(1):90-97). Finite element modeling is likely the only current method, other than invasive testing of live subjects with implanted strain gauges, to experimentally determine the relative contributions of the plantar fascia, plantar ligaments and plantar intrinsic and extrinsic muscles to increasing longitudinal arch stiffness. The list of references which follows is only a partial list of other finite element references that demonstrate that the plantar fascia and plantar ligaments together share considerable tension loads to maintain longitudinal arch stiffness during weightbearing activities of the foot, further supporting the concepts of the LALSS of the foot. Cheung JT, An KN, Zhang M. Consequences of partial and total plantar fascia release: a finite element study. Foot & ankle international. 2006 Feb;27(2):125-32. Wu L. Nonlinear finite element analysis for musculoskeletal biomechanics of medial and lateral plantar longitudinal arch of Virtual Chinese Human after plantar ligamentous structure failures. Clinical Biomechanics. 2007 Feb 1;22(2):221-9. Cheng HY, Lin CL, Wang HW, Chou SW. Finite element analysis of plantar fascia under stretchthe relative contribution of windlass mechanism and Achilles tendon force. Journal of biomechanics. 2008 Jan 1;41(9):1937-44. Cheng HY, Lin CL, Chou SW, Wang HW. Nonlinear finite element analysis of the plantar fascia due to the windlass mechanism. Foot & ankle international. 2008 Aug;29(8):845-51. Tao K, Ji WT, Wang DM, Wang CT, Wang X. Relative contributions of plantar fascia and ligaments on the arch static stability: a finite element study. Biomedical Engineering/Biomedizinische Technik. 2010 Oct 1;55(5):265-71. Liang J, Yang Y, Yu G, Niu W, Wang Y. Deformation and stress distribution of the human foot after plantar ligaments release: A cadaveric study and finite element analysis. Science China Life Sciences. 2011 Mar 1;54(3):267-71. Chen YN, Chang CW, Li CT, Chang CH, Lin CF. Finite element analysis of plantar fascia during walking: a quasi-static simulation. Foot & ankle international. 2015 Jan;36(1):90-7.

08.01.2022 Anatomy, Range of Motion and Neutral Position of the Subtalar Joint The talus and calcaneus make up the two bones of the subtalar joint (STJ), otherwise known a...s the talo-calcaneal joint. The STJ consists of three articular facets, the posterior, middle and anterior facets. The two physiologic motions of the STJ are supination and pronation. During STJ supination, the talus glides posterior-superiorly on the posterior facet of the calcaneus. During STJ pronation, the talus glides anterior-inferiorly on the posterior facet of the calcaneus. The maximally pronated position of the STJ occurs when the lateral process of the talus hits the floor of the sinus tarsi of the calcaneus. STJ supination involves posterior translation and abduction and dorsiflexion rotation of the talus relative to the calcaneus. STJ pronation involves anterior translation and adduction and plantarflexion rotation of the talus relative to the calcaneus. The neutral position of the STJ likely occurs when the posterior articulating facets of the STJ are most congruent to each other. With maximal pronation of the STJ, the anterior half of the talar posterior articulating facet separates from the posterior facet of the calcaneus. With supination of the STJ, the posterior half of the talar posterior articulating facet separates from the posterior facet of the calcaneus. Understanding the three-dimensional rotations and translations of the talus relative to the calcaneus is the key to understanding STJ biomechanics, including the functional significance of the STJ maximally pronated position, neutral position and STJ rotational stability during weightbearing activities.

08.01.2022 Ganglion Aspiration Without Anesthetic or Syringe I performed this ganglion aspiration on a 49 year-old female patient who has had a ganglion recur on and off o...ver the past five years on the dorsal aspect of her forefoot. The ganglion was about 3.0 cm x 3.0 cm in area and about 8 mm thick, filled with about 3-4 cc of fluid. In this procedure, no syringe or local anesthetic is necessary. After sterile prep with a povidone-iodine solution, ethyl chloride is sprayed onto the ganglion for about 5-6 seconds to temporarily numb the skin over the ganglion. Then an 18-gauge hypoderemic needle is used to puncture the lateral aspect of the gangion. The ganglionic fluid is then fully expressed out of the ganglion using manual pressure on the top and sides of the ganglion. A sterile 2x2" gauze and 3" coban wrap is then used for a compression dressing which is kept on for 24 hours. Total procedure time for this alternative ganglion aspiration technique is about 5 minutes. I have used this ganglion aspiration technique now for the past 25 years and have never had any problems with the procedure. Patients are pain-free the next day after the procedure and are also able to perform full activities the day following the procedure.

06.01.2022 Anterior Displacement of Plantar Fat Pad in Forefoot with Digital Deformities-Another Cause of Thinning of the Plantar Fat Pad An excellent study on the cause ...of thin fat pads plantar to the metatarsal heads in the forefoot was performed by Bus et al in 2004. Bus et al measured plantar metatarsal fat pad thickness in 13 diabetic neuropathic (DN) individuals with digital deformity, in 13 DN individuals without digital deformity and in 13 controls without digital deformity. High resolution sagittal plane MRI images were taken of the subjects to assess plantar forefoot fat pad thickness. Fat pad thickness plantar to the metatarsal heads was significantly decreased only in subjects with digital deformity. Plantar metatarsal head fat pad thickness was not decreased in subjects without digital deformity, whether they had DN or not. The authors concluded that their study showed a distal displacement and subsequent thinning of the sub-metatarsal head fat pads in neuropathic diabetic patients with toe deformity and suggests that, as a result, the capacity of the tissue in this region to reduce focal plantar pressure is severely compromised. They also suggested that the combination of DN along with digital deformity likely increases the risk of plantar forefoot ulceration due to this anterior migration of the plantar forefoot fat pad in these patients (Bus SA, Maas M, Cavanagh PR, Michels RP, Levi M. Plantar fat-pad displacement in neuropathic diabetic patients with toe deformity: a magnetic resonance imaging study. Diabetes Care, 27(10):2376-2381, 2004).

05.01.2022 Some babies with clubfooot have had to have their casting treatment paused due to COVID-19. This video, produced in partnership with Global Clubfoot Initiative shows simple movements and exercises that help to keep the feet moving and mobile.

03.01.2022 Standing Subtalar Joint Axis Location Technique The axis of motion of the subtalar joint (STJ) should be of special interest to all podiatrists and foot-health ...clinicians since the spatial location of the STJ axis relative to the plantar aspect of the foot largely determines the kinetics (i.e. forces and moments) of the STJ during weightbearing activities (Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001). I described the first technique described within the scientific literature that determined the plantar representation of the STJ axis in a paper from 33 years ago (Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987). This STJ Axis Palpation Technique I invented involves the examiner using their thumb to repeatedly push on the plantar aspect of the foot to determine the points where neither pronation nor supination motion was produced (i.e. points of no rotation). Connecting these points of no rotation represents the STJ axis plantar location which, in turn, allows the clinician to determine whether their patient’s STJ axis is normally located, medially deviated from normal or laterally deviated from normal within the transverse plane One of the biggest problems with this STJ Axis Palpation Technique (SAPT) is that it is performed in a non-weightbearing setting. During the performance of the SAPT, the medial aspect of the patient’s plantar forefoot is completely unloaded since the examiner’s hand supports the plantar forefoot only under the 5th metatarsal head. The lack of plantar loading on the medial forefoot during the SAPT may lead to an underestimation of the amount of STJ axis medial deviation present in the weightbearing foot since the medial forefoot may dorsiflex (i.e. forefoot may invert) relative to the rearfoot upon standing and/or walking. In addition, the STJ axis location may also be difficult to determine in feet with excessive inverted forefoot deformities (i.e. forefoot varus/supinatus deformities) since the STJ will already be in the maximally pronated position in these feet during the SAPT. If the STJ is already maximally pronated during performance of the SAPT, when the examiner pushes lateral to the STJ axis, the STJ can pronate no further, thus making it difficult to determine the points of no rotation when performing the SAPT (Kirby KA, 1987). Approximately 15 years ago, due to these problems inherent in performing the SAPT, I began to develop a technique by which to assess the STJ axis spatial location while the patient was weightbearing, in relaxed bipedal stance. This new clinical method of STJ axis determination, which I call the Standing Subtalar Joint Axis Location Technique (SSALT), is based on my observations from using the clinical technique first described by Morris and Jones where grids of pen marks are drawn on the posterior calcaneus and anterior talar neck and then used to determine the posterior and anterior exit points of the STJ axis from the foot (Morris JL, Jones LJ: New techniques to establish the subtalar joint’s functional axis. Clin Podiatr Med Surg,11: 301, 1994). To perform the SSALT, the patient is asked to stand in relaxed bipedal stance while the examiner uses a pen to draw a rectangular box which outlines the superior-lateral quadrant of the posterior calcaneus (Fig. 1). An X is then placed in the center of that box, which represents the posterior exit point of the STJ axis. An X is also drawn centered over the dorsal aspect of the talar neck anteriorly which represents the anterior exit point of the STJ axis. Then, using a pen to represent the STJ axis, one end of the pin is placed on the X at the dorsal talar neck while the examiner then aligns the longitudinal axis of the pen so that it points, through the foot, towards the X located at the center of the superior-lateral quadrant of the posterior calcaneus. If performed accurately, the 3D location of the examiner’s pen now represents the approximate location of the STJ axis spatial location, allowing the visualization by the examiner of the STJ axis location relative to the structures of the dorsal foot. Not only does the SSALT allow the STJ axis to be represented visually in 3D space, showing both its transverse plane alignment and its sagittal plane inclination, but it also allows the STJ axis to be located in a weightbearing setting. Of course, the exact 3D location of the STJ axis cannot be determined using either the SSALT or the SAPT. However, the relatively new SSALT is a valuable method by which to clinically assess the STJ axis spatial location to help determine the best foot orthosis modifications and/or surgical procedures to treat our patient’s foot and lower extremity mechanically-based pathologies. [Reprinted with permission from the July 2017 Precision Intricast Newsletter in: Kirby KA: Foot and Lower Extremity Biomechanics V: Precision Intricast Newsletters, 2014-2018. Precision Intricast, Inc., Payson, AZ, 2018, pp. 87-88.]

03.01.2022 "It's like Netflix for medical lectures!" This is the first time complex medical conditions are explained in an easy to understand way. Perfect for Medical & Nu...rsing Students. But even those already working as a Nurse or Doctor can greatly benefit from these lectures! We have to admit, with over 800+ videos on basic and clinical medicine, it's hard to fight the urge to binge watch. We get it. That's why we offer our members multiple playback speeds. Tap [SIGN UP] to receive lifetime access and save up to 80%

03.01.2022 The Vertical Calcaneus: Is It Really "Normal"? Classic podiatric biomechanics, as taught by Dr. Merton Root and colleagues, taught that the vertical position o...f the calcaneus was a very important parameter to determine whether a foot is "normal" or not. If a patient stands in relaxed calcaneal stance position (RCSP) and is noted to have an inverted calcaneus, it was assumed that there must be some biomechanical pathology causing the calcaneus to be abnormally inverted. If a patient stands in RCSP and has an everted calcaneus, classic podiatric biomechanics taught that one should assume that some biomechanical pathology is causing the calcaneus to be abnormally everted. At the time I learned these concepts while I was a podiatry student at the California College of Podiatric Medicine from 1979 to 1983, this seemed like a very neat way to make foot biomechanics more easy and simple to understand. Unfortunately, the foot is not quite that easy or simple. The main problem with relying on calcaneal bisections to determine whether a foot is "normal" or "abnormal" is that the whole method by which the bisection of the calcaneus is clinically determined is flawed. Since we can only see skin and have to palpate through skin and fat in order to estimate the actual shape of the posterior calcaneus, there is at least a +/- 5 degree range of error in performing heel bisections with most podiatrists. I have observed this time and again in my 35+ years of teaching foot and lower extremity biomechanics to podiatry students, residents and podiatrists. The main problem which I have with the calcaneal bisection is not in its accuracy of clinical measurement but in the idea that the calcaneal bisection has some significant effect on foot biomechanics. In other words, I have a problem in using the RCSP as the basis of comparison of one foot's biomechanical makeup to another foot's biomechanical makeup. I feel that the position of the posterior surface of the calcaneus to the ground has very little biomechanical effect on the overall pronation and supination moments acting across the subtalar joint during standing. In order to analyze this concept further one must entertain the thought that the posterior surface of the calcaneus has no special biomechanical significance other than that it just so happens to be the part of the foot which is the easiest part of the calcaneus to observe, palpate and attempt to clinically bisect To better explain my reasoning, it is helpful to compare the calcaneus to balancing blocks of wood of different shapes (see Figures 1-4). First, what physical factors determines whether a block of wood will balance on a flat surface? In order for any object to balance or remain stable on a flat surface with no other external forces acting on it, the center of mass of that object must be positioned somewhere over the base of support of that object (Fig. 1). If the center of mass is positioned somewhere out of the base of support of that object, then that object will fall (i.e. rotate toward its supporting surface) because it is unstable (Fig. 2). If the same object instead now has a rounded surface which is resting on a flat surface, there is only one position in which that object will balance: it will balance only when the center of mass of that object is directly over the point of contact of that object (Fig. 3). Like the block of wood in Figure 3, the calcaneus is always resting on the rounded surface of the medial calcaneal tubercle during standing (Kirby KA, Loendorn AJ, Gregorio R: Anterior axial projection of the foot, JAPMA,, 78: 159-170, 1988.) Now, if the object (Fig. 4) not only has a rounded bottom but also has a curved or complex shape to its body (i.e. as does the calcaneus), where will it balance? To determine where it will balance should we bisect the middle of it, the bottom of it, or the top of it? Should we bisect it at all? Again the same mechanical principles which determine how a more complex-shaped object will balance should also be applied to a less complex-shaped object which which has straight and parallel sides. The complex object in Figure 4 will only balance when its center of mass is resting over its point of contact with the supporting surface. It really doesn't matter what relative position that the central, top or bottom aspects of this object has to the supporting surface. The only physical parameter that is important is the position of the center of mass in relation to the point of support of this object, since gravitational acceleration acting at the center of mass will determine the position that object will balance on the ground. Using these basic physics principles, it then seems logical that the position of the posterior surface of the calcaneus to the ground has little biomechanical effect on the foot. What is important relative to the frontal plane shape of the calcaneus is the position of the point of support of the calcaneus (i.e. the medial calcaneal tubercle) to the subtalar joint axis. I still believe the clinician can use the calcaneal bisection as a reference for the frontal plane position of the calcaneus so that motions of the calcaneus during standing and during gait may be more easily observed and measured. However, to use calcaneus verticality as a standard for determining whether feet are "normal" or "abnormal" is to ignore the basic concepts physics and thus, the basic principles of foot and lower extremty biomechanics. [Edited with permission from my October 1993 Precision Intricast Newsletter in: Kirby KA: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997, pp. 37-38.]

01.01.2022 Is Plantar Fascia Tension Force High Both in Late Midstance and Early Propulsion? One of the classic, and in my opinion, best research articles on plantar fas...cia tension during walking gait came from a group of biomechanics researchers at Penn State Biomechanics Laboratory led by Ahmet Erdemir from 16 years ago (Erdimir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA: Dynamic loading of the plantar aponeurosis in walking. JBJS, 86A:546-552, 2004). The researchers used seven fresh-frozen cadaver foot and leg preparations which were thawed to room temperature and then mounted the preparations into a "dead-man walking machine" or "dynamic gait simulator"/ Their dynamic gait simulator used servomotors attached to all the extrinsic muscle tendons of the foot so that the cadaver foot-leg could walk over the ground surface. Plantar fascial tension was measured in the cadaver specimens using 0.5 mm fiber-optic cable embedded within plantar fascia which was then calibrated, after the cadaver walking experiment was performed on the cadaver specimens, in a materials testing device (see photo and illustrations from paper below). The researchers found that the tension within the plantar fascia was low in early stance phase and peaked just after heel-off as the windlass function of the plantar fascia was engaged with hallux dorsiflexion. The plantar fascia tension gradually increased during midstance and very early propulsion to peak at a maximum force of 0.96 times body weight. In addition, Achilles tendon tension force was found to be an effective predictor of plantar fascial tension (r = 0.76). Note from the plantar fascia tension force graphs below that the plantar fascia still has relatively high tension forces during early propulsion and late midstance, indicating that its ability to create stiffness within the longitudinal arch is very good during these phases of gait. The notion that the plantar fascia and windlass are only minor contributors to longitudinal arch stiffness is not supported by this unique and excellent experimental study which directly measured plantar fascia tension in cadaver feet "walking" in Penn State Biomechanics Lab's brilliant dynamic gait simulator. https://www.researchgate.net//Dynamic-Loading-of-the-Plant