Biomechanical consequences of adding plantar fascia release to metatarsal osteotomies: Changes in forefoot plantar pressures

Destruction of the normal metatarsal arch by a long metatarsal is often a cause for metatarsalgia. When surgery is warranted, distal oblique, or proximal dorsiflexion osteotomies of the long metatarsal bones are commonly used. The plantar fascia has anatomical connection to all metatarsal heads. There is controversial scientific evidence on the effect of plantar fascia release on forefoot biomechanics. In this cadaveric biomechanical study, we hypothesized that plantar fascia release would augment the plantar metatarsal pressure decreasing effects of two common second metatarsal osteotomy techniques. Six matched pairs of foot and ankle specimens were mounted on a pressure mat loading platform. Two randomly assigned surgery groups, which had received either distal oblique, or proximal dorsiflexion osteotomy of the second metatarsal, were evaluated before and after plantar fasciectomy. Specimens were loaded up to a ground reaction force of 400 N at varying Achilles tendon forces. Average pressures, peak pressures, and contact areas were analyzed. Supporting our hypothesis, average pressures under the second metatarsal during 600 N Achilles load were decreased by plantar fascia release following proximal osteotomy (p < 0.05). However contrary to our hypothesis, peak pressures under the second metatarsal were significantly increased by plantar fascia release following modified distal osteotomy, under multiple Achilles loading conditions (p < 0.05). Plantar fasciotomy should not be added to distal metatarsal osteotomy in the treatment of metatarsalgia. If proximal dorsiflexion osteotomy would be preferred, plantar fasciotomy should be approached cautiously not to disturb the forefoot biomechanics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:800–804, 2017.

     

Biomechanical consequences of plantar fascial release or rupture during gait. Part II: alterations in forefoot loading

With a model using feet from cadavers, we tested the hypothesis that plantar fascial release or rupture alters the loading environment of the forefoot during the latter half of the stance phase of gait. The model simulated the position and loading environment of the foot at two instants: early in terminal stance immediately after heel-off and late in terminal stance just preceding contralateral heel strike. Eight feet were loaded at both positions by simulated plantar flexor contraction, and the distribution of plantar pressure was measured before and after progressive release of the plantar fascia. Strain in the diaphysis of the second metatarsal was also measured, from which the bending moments and axial force imposed on the metatarsal were calculated. Cutting the medial half of the central plantar fascial band significantly increased peak pressure under the metatarsal heads but had little effect on pressures in other regions of the forefoot or on second metatarsal strain and loading. Dividing the entire central band or completely releasing the plantar fascia from the calcaneus had a much greater effect and caused significant shifts in plantar pressure and force from the toes to beneath the metatarsal heads. These shifts were accompanied by significantly increased strain and bending in the second metatarsal. Complete fasciotomy increased the magnitude of strain in the dorsal aspect of the second metatarsal by more than 80%, suggesting that plantar fascial release or rupture accelerates the accumulation of fatigue damage in these bones. Altered forefoot loading may be a potential complication of plantar fasciotomy.     

An evaluation of the long-term effects of total plantar fasciotomy—A preliminary study

BackgroundPlantar fascia release for chronic plantar fasciitis has given excellent pain relief and rapid return to activities with few reported complications. Cadaveric studies have led to the identification of some potential post-operative problems, commonly weakness of the medial longitudinal arch (MLA) and pain in the lateral midfoot.MethodsEight total plantar fasciotomy patients (five bilateral and three unilateral) were evaluated subjectively and objectively with regards to surgical outcome and biomechanical change. The centre of pressure (COP) and loading of the foot were measured using the F Scan mobile system and COM’nalysis software. In addition, five control subjects were evaluated with the F Scan. The reading for one foot of one of the control subjects was discarded due to a biomechanical abnormality.ResultsThe results of this study were that the COP of the foot in post-total plantar fasciotomy subjects was significantly laterally deviated throughout the propulsive phase of gait compared to that of control subjects (p < 0.05). There was no significant difference in plantar pressure at the rearfoot or the first metatarsophangeal joint (MTPJt) between the post-operative and control groups (p > 0.05). Six of the eight of the post-operative patients (11 feet) considered the procedure to be successful in resolving their symptoms.ConclusionTotal plantar fasciotomy may result in changes to the COP of the foot. It could be extrapolated from this data, in conjunction with subjective visual clinical observations of gait, that supination of the foot could occur post-operatively rather than the pronatory state secondary to a collapsed arch that, collectively, the results of cadaver studies have suggested. The conclusions drawn from this pilot study are to some extent speculative, as the measurements were only made post-operatively and a small number of subjects were studied. Further research is required in this area.     

Plantar fascia release through a transverse plantar incision.

A transverse plantar incision for plantar fascial release was assessed for pain relief, numbness, and subsequent heel pad symptoms. Twenty-seven feet in 26 patients who underwent plantar fascia release were reviewed with a minimum follow-up of 2 years after surgery (average, 37.6 months). Comprehensive data were obtained on 25 feet (24 patients) (93% response rate). The plantar fascia origin was completely transected in all cases. This led to complete resolution of symptoms in 19 feet and residual minor symptoms in six feet. After 2 years, four patients had developed recurrent symptoms, two in the area of surgery and two on the dorsum of the foot, in association with a pes planus foot. Two patients had some continued persistence of heel pain after surgery, although significantly less pain than preoperatively.Thus, 76% of patients had complete relieve of there symptoms, 12% of patients had mild symptoms not affecting daily activities, and 12% of patients had moderate symptoms that limited some activities. No patient suffered heel pad symptoms or numbness after surgery. It is concluded that plantar fascia release through a transverse plantar incision is a successful procedure for long-term relief of symptoms which avoids unnecessary heel pad numbness and scar morbidity. The benefits of a transverse incision include greater intraoperative vision, to ensure adequate release and spur excision, and an incision parallel to the medial calcaneal branches of the tibial nerve.     

The effect of pre-fabricated insole on plantar pressure distribution in patients with rheumatoid arthritis

BackgroundFoot deformities result in pain and changes in plantar pressure distribution in rheumatoid arthritis (RA) patients. Medical insoles are commonly prescribed for declining pain and modifying foot pressure distribution in these patients. The purpose of this study was to evaluate the effect of a pre-fabricated insole with metatarsal pad and medial longitudinal arch support on plantar pressure distribution in rheumatoid arthritis patients.MethodsFifteen females with RA participated in this study. All patients received a pair of pre-fabricated insoles that were individually modified using metatarsal pads and medial longitudinal arch supports. Mean peak pressure (kPa), maximum force (N), and contact area (cm²) were calculated for the heel, midfoot, metatarsophalangeal joint, and toe regions using the Pedar-X system immediately and after a month follow-up.FindingsIn the heel and metatarsophalangeal joint regions, maximum pressure and force showed a significant reduction in the follow-up assessment (p < 0.05). The comparison showed a significant increase in maximum pressure and force in the midfoot when participants walked with insole compared to without insole condition (p < 0.001).InterpretationUsing a pre-fabricated insole with an individually modified metatarsal pad and medial longitudinal arch support could alter rheumatoid arthritis patients’ plantar pressures after one month of follow-up. This type of insole is simple and inexpensive and showed a significant effect on decreasing pressures under the metatarsal heads.     

Treatment of recalcitrant plantar fasciitis by sonographically-guided needle fasciotomy

Plantar fasciotomy was carried out in 32 patients who had typical heel pain that had persisted for three months or longer. Following induction of local anesthesia, an 18-gauge needle was guided toward and into the plantar fascia by real-time sonography. The criterion for operative success was the appearance of an acoustic window within the plantar fascia. Pain intensity was graded on an 11-point visual analog scale (VAS). Questionnaires combining the VAS and a 0–100 point Daly score were filled out after treatment to determine the effectiveness of the procedure. The follow-up averaged 13.5 months. 78% were overweight (BMI>25). The mean pain score decreased by 6.72 points, a 73±21% improvement (P<0.001). The mean post-operative Daly score was 88.3±16.2. There were no complications during or after the procedure.Sonographically-guided needle fasciotomy is a safe and effective method for the relief of conservatively unmanageable heel pain due to plantar fasciitis.     

Endoscopic plantar fasciotomy for chronic heel pain

The purpose of our study was to determine whether endoscopic plantar fasciotomy is a safe and effective operation in this patient population. We reviewed our surgical results following endoscopic plantar fasciotomy in sixteen patients (twenty feet) with an average preoperative duration of symptoms of four years. Of the 20 feet, 9 had complete relief of pain while symptoms were improved in nine feet. One patient with bilateral symptoms had no relief in either foot. The average AOFAS hindfoot score improved from 62 to 80, a statistically significant difference. Unilateral patients did better than bilateral with no bilateral patients reporting complete resolution of symptoms. There were no iatrogenic nerve injuries. On the basis of our review, we recommend endoscopic plantar fasciotomy as an alternative to open plantar fascial release for those patients with recalcitrant heel pain.     

Lateral column symptomatology following plantar fascial release: A prospective study

Plantar fasciitis or heel spur syndrome usually resolves with conservative management, but for patients with continued pain, surgical intervention is often pursued. In some cases, plantar fasciitis is relieved, but pain in the lateral column area appears postoperatively. This lateral column pain may be debilitating for the patient and often overlooked by the foot and ankle surgeon. The goal of the study was to identify the maximum amount of plantar fascia that can be surgically released to treat recalcitrant heel pain effectively while preventing the development of lateral column symptoms. All patients undergoing plantar fasciotomy after failing conservative treatment were eligible to participate. Patients rated their pain with an 11-point (0-10) visual analog scale (VAS) and described its location prior to and at monthly intervals after their surgery. Surgeons recorded whether 25, 50, or 66% of the plantar fascia was released during surgery. Open procedures were performed 72% of the time, and endoscopically in 28% of the patients. Key outcome variables included degree of fascial release and foot structure. Patients (n = 47) with lateral column pain after surgery (n = 15 feet) had a mean +/- S.E. of 60.6 +/- 3.0% of their plantar fascia released while those without pain (n = 35 feet) had only 48.7 +/- 1.9% of this fascia released during surgery (ANOVA, p = .019). Age, weight, body mass index, gender, smoking status, comorbidities, general health, surgical procedure, postoperative care, calcaneal inclination angle, and talar declination angle did not differ for these groups (p > .146). For this patient population, regardless of surgical technique (endoscopic or open release), lateral column symptoms were more likely to result when more than 50% of the plantar fascia was released. The report proposes that a maximum of 50% of the plantar fascia be released during surgery.     

Contributions of active and passive toe flexion to forefoot loading.

Toe flexion during terminal stance has an active component contributed by the muscles that flex the toes and a passive component contributed by the plantar fascia. This study examined the relative importance of these two mechanisms in maintaining proper force sharing between the toes and forefoot. Thirteen nonpaired cadaver feet were tested in a dynamic gait stimulator, which reproduces the kinematics and kinetics of the foot, ankle, and tibia by applying physiologic muscle forces and proximal tibial kinematics. The distribution of plantar pressure beneath the foot was measured at the terminal stance phase of gait under normal extrinsic muscle activity with an intact plantar fascia, in the absence of extrinsic toe flexor activity (no flexor hallucis longus or flexor digitorum longus) with an intact plantar fascia, and after complete fasciotomy with normal extrinsic toe flexor activity. In the absence of the toe flexor muscles or after plantar fasciotomy the contact area decreased beneath the toes and contact force shifted from the toes to the metatarsal heads. In addition, pressure distribution beneath the metatarsal heads after fasciotomy shifted laterally and posteriorly, indicating that the plantar fascia enables more efficient force transmission through the high gear axis during locomotion. The plantar fascia enables the toes to provide plantar-directed force and bear high loads during push-off.     

Pathologic conditions of the plantar fascia

Plantar heel pain in adults is commonly seen in the office of the podiatric foot and ankle specialist. These symptoms may have developed acutely or over a period of time. Often the plantar fascia is the source of the pain, which is caused by a traumatic event or a biomechanical flaw. It is imperative that the podiatric physician understands the multiple causes of plantar foot pain and is able to differentiate the multiple causes of heel pain to confirm a specific diagnosis and formulate a proper treatment plan. A thorough history and physical examination are necessary to obtain this information, and diagnostic procedures are sometimes needed.     

Five-year follow-up results of instep plantar fasciotomy for chronic heel pain.

The results of a 5-year follow-up of patients who underwent surgical partial release of plantar fascia with plantar skin incision for treatment of chronic heel pain are presented. Evaluation included survey results from both a modified Mayo Scoring System and a list of specific questions developed by the authors. Thirty-three feet of 30 patients are evaluated. Thirty of the 33 feet studied achieved good or excellent results, scoring 80 or better on a 100-point scale. Ninety percent pain relief was achieved in 27 of the 33 feet studied (81.8%). A satisfaction rate of 90% or better was found with 30 of the 33 feet studied (90.9%). Long-lasting complications were described by five patients, including opposite foot pain, dorsal foot pain after extended activity, scar tissue discomfort, callus at scar area, and continued heel pain.     

Endoscopic Plantar Fasciotomy Through Two Medial Portals for the Treatment of Recalcitrant Plantar Fasciopathy

Plantar fasciopathy is a common cause of heel pain. Endoscopic plantar fasciotomy has the advantage of less surgical trauma and rapid recovery. The aim of the present prospective study was to delineate the results of endoscopic plantar fascia release through 2 medial portals. The present study included 2 groups. The first group included 27 feet in 25 patients that had undergone endoscopic plantar fascia release followed up for 19.7 (range 12 to 33) months. The second group, the control group, included 20 feet in 16 patients treated conservatively and followed up for 16.4 (range 12 to 24) months. The results of endoscopic plantar fascia release were superior to the conservative methods. The surgically treated group experienced significantly less pain, activity limitations, and gait abnormality. The presence of a calcaneal spur had no effect on the final postoperative score. In conclusion, endoscopic plantar fascia release through 2 medial portals is an effective procedure for treatment of resistant plantar fasciopathy that fails to respond to conservative management options.     

Strains in the metatarsals during the stance phase of gait: implications for stress fractures.

BACKGROUND: Stress fractures of the metatarsals are common overuse injuries in athletes and military cadets, yet their etiology remains unclear. In vitro, high bone strains have been associated with the accumulation of microdamage and shortened fatigue life. It is therefore postulated that stress fractures in vivo are caused by elevated strains, which lead to the accumulation of excessive damage. We used a cadaver model to test the hypothesis that strains in the metatarsals increase with simulated muscle fatigue and plantar fasciotomy. METHODS: A dynamic gait simulator was used to load fifteen cadaveric feet during the entire stance phase of gait under conditions simulating normal walking, walking with fatigue of the auxiliary plantar flexors, and walking after a plantar fasciotomy. Strains were measured, with use of axial strain-gauges, in the dorsal, medial, and lateral aspects of the diaphysis of the second and fifth metatarsals as well as in the proximal metaphysis of the fifth metatarsal. RESULTS: When the feet were loaded under normal walking conditions, the mean peak strain in the dorsal aspect of the second metatarsal (-1897 microstrain) was more than twice that in the medial aspect of the fifth metatarsal (-908 microstrain). Simulated muscle fatigue significantly increased peak strain in the second metatarsal and decreased peak strain in the fifth metatarsal. Release of the plantar fascia caused significant alterations in strain in both metatarsal bones; these alterations were greater than those caused by muscle fatigue. After the plantar fasciotomy, the mean peak strain in the dorsal aspect of the second metatarsal (-3797 microstrain) was twice that under normal walking conditions. CONCLUSIONS: The peak axial strain in the diaphysis of the second metatarsal is significantly (p < 0.0001) higher than that in the diaphysis of the fifth metatarsal during normal gait. The plantar fascia and the auxiliary plantar flexors are important for maintaining normal strains in the metatarsals during gait.     

Computer-assisted assessment of lateral column movement following plantar fascial release: a cadaveric study.

In patients who fail conservative treatment, releasing the plantar fascia relieves heel pain but destabilizes the lateral column of the foot. After surgery, pain can present in the area of the sinus tarsi, extensor digitorum brevis muscle, between the fourth and fifth metatarsals, and at the calcaneocuboid joint. The precise mechanism and involved structures for this painful compensation remains unclear. The authors hypothesized that the lateral plantar fascial band, bifurcate and cervical ligaments, lateral talocalcaneal ligament, and interosseous talocalcaneal ligament become excessively strained after this surgery. Using eight cadaver lower extremity limbs amputated 7 cm above the ankle joint, structural changes in the foot in response to staged release of the plantar fascia were measured. All ligament, tendon, and osseous structures were exposed along the plantar, medial, and lateral aspects of the foot and ankle. Using a servohydraulic system, compressive loads in increasing increments (50 lbs) were applied along the tibial axis. Tissue and bony structure displacement in the foot was measured using images electronically captured from two fixed cameras and a digital camera following each load change. All measurements were made in pixels and converted to millimeters in a spreadsheet program. Except for plantar fascial measurements, data were expressed as percentage of initial baseline. As expected, increasing compressive loads changed all measurements [repeated measures ANOVA, p<.04]. When releasing the plantar fascia, the inferior sinus tarsi space widened (intact, 85.4+/-10.8%; 1/4 release, 87.7+/-13.0; 1/2 release, 88.3+/-9.2; 3/4 release, 91.2+/-8.8; p<.04). Lateral length increased and medial height decreased, while medial length and lateral height were unchanged as the fascia was sequentially released. Significant movement of the inferior sinus tarsi strained the bifurcate and cervical ligaments, the lateral talocalcaneal ligament, and interosseous talocaneal ligament, which may account for pain following surgery. The initial 1/4 cut of the plantar fascia exerted the greatest mechanical alteration of the foot, suggesting that a partial release may relieve heel pain while optimizing the patient's chances of maintaining structural integrity with 75% of the plantar fascia intact.     

Foot pressures during gait: a comparison of techniques for reducing pressure points

PURPOSE: Various methods have been used to redistribute plantar surface foot pressure in patients with foot ulcers. This study was conducted to determine the effectiveness of four modalities (fracture walker, fracture walker with insert, and open and closed toe total contact casts) in reducing plantar foot pressure. METHODS: Ten healthy, normal volunteer subjects had an F-scan sensor (ultra thin shoe insert pressure monitor) placed under the right foot. They then ambulated on a flat surface, maintaining their normal gait. Dynamic plantar pressures were averaged over 10 steps at four different sites (plantar surface of great toe, first metatarsal head, base of fifth metatarsal, and plantar heel). All subjects repeated this sequence under five different testing conditions (barefoot, with a fracture walker, fracture walker with arch support insert, open and closed toe total contact cast). Each subject's barefoot pressures were then compared with the pressures during the different modalities. RESULTS: All four treatment modalities significantly reduced (p < 0.05) plantar pressure at the first metatarsal head (no method was superior). The fracture walker, fracture walker with insert, and open toe total contact cast significantly reduced pressure at the heel. Pressures at the base of the fifth metatarsal and great toe were not significantly reduced with any treatment form. CONCLUSION: The fracture walker, with and without arch support, and total contact cast can effectively reduce plantar pressure at the heel and first metatarsal head.     

两种第二趾切取游离移植对供足足底应力影响的生物力学研究

目的 探讨第2足趾切取游离移植对供足足底应力的影响.方法 取6具正常成人新鲜尸体足标本,根据不同状态分3组:完整组(A组)、第2趾截除(保留跖骨头)组(B组)及带部分跖骨的第2趾截除(跖骨远l/3处)组(C组).应用电子万能试验机以2 mm/min的速度从胫骨远端施加轴向压载,加载载荷分别为0、600、1200 N.通过F-Scan足底压力测量系统检测足底应力变化,并对数据进行统计学分析.结果 足底应力随轴向压载的增加而增大.A组(足母)指及5个跖骨头的峰值压强以第2跖骨头最大,600 N垂直载荷时为(37.33±7.34)kPa,1200 N垂直载荷时为(112.33±10.33)kPa.同一载荷下,A组与B组的(足母)指及5个跖骨头的峰值压强差异均无统计学意义(P>0.05).同一载荷下,A组、B组分别与C组比较,(足母)指及5个跖骨头的峰值压强差异均有统计学意义(P<0.05).结论 第2跖骨的完整对足底应力正常分布及维持足弓具有重要意义.保留跖骨头的第2趾切取对供足足底应力分布影响较小,带部分跖骨的第2趾切取可导致供足足底应力的异常分配.     

微创治疗老年跟骨结节骨赘型跟痛症临床疗效分析

[目的]探讨老年(年龄≥60岁)跟骨结节骨赘型跟痛症微创治疗的临床疗效.[方法]对2000年7月～2010年7月本院治疗的159例(173足)跟骨结节骨赘型跟痛症老年患者的手术方式及疗效进行分析.根据Maryland 评分患者均＜50分,其中82足(微创组)患者接受了微创骨赘切除、跖腱膜止点松解、滑囊切除手术,91足(开放组)接受开放式手术.[结果]共有93例(104足)获得随访,随访时间6～26个月,平均19个月,其中微创组55足疼痛完全消失,行走无影响;2足明显好转,剧烈活动后,有疼痛感,休息后缓解;开放组45足疼痛完全消失,行走无影响;1足好转,剧烈活动后,有疼痛感,休息后缓解;1足,半年内瘢痕疼痛,半年后瘢痕软化,疼痛消失.[结论]针对跟骨结节骨赘致跟痛症老年患者,微创及开放式手术通过松解跖腱膜止点,切除骨赘及滑囊治疗,效果 均令人满意.相比于开放式手术,微创术式因其创伤较小,恢复较快而更容易被患者接受.     

Percutaneous Plantar Fascia Release With Needle: Anatomic Evaluation with Cadaveric Specimens

Percutaneous plantar fascia release with needle is a novel procedure for the treatment of plantar fasciitis. The objective of this cadaveric study is to perform an anatomic evaluation of the percutaneous plantar fascia release method using a conventional hypodermic needle. In this study, we used 14 fresh-frozen cadaveric trans-tibial amputation specimens. Percutaneous plantar fasciotomy with a conventional hypodermic needle was performed. After a proper dissection, the width of the plantar fascia, the thickness of the medial border, and the width of the cut segment were measured and recorded. Any muscle damage on the flexor digitorum brevis and damaged area depth were recorded. Any damage on the lateral plantar nerve and the first branch of the lateral plantar nerve, also known as Baxter's nerve, and their distance to fasciotomy were also recorded. Mean width (± standard deviation) of the plantar fascia was measured as 20.34 ± 4.25 mm. The mean thickness of the medial border of the plantar fascia was 3.04 ± 0.54 mm. Partial fasciotomy was performed in all cadavers with 49.47% ± 7.25% relative width of the plantar fascia. No lateral plantar nerve, or its first branch Baxter's nerve, was damaged, and the mean distance from the deepest point of the fasciotomy up to the Baxter's nerve was 8.62 ± 2.62 mm. This cadaveric study demonstrated that partial plantar fasciotomy can be achieved via percutaneous plantar fascia release with a conventional hypodermic needle without any nerve damage.     

Role of mechanical factors in the clinical presentation of plantar heel pain: Implications for management

Plantar heel pain is a common musculoskeletal foot disorder that can have a negative impact on activities of daily living and it is of multifactorial etiology. A variety of mechanical factors, which result in excessive load at the plantar fascia insertion, are thought to contribute to the onset of the condition. This review presents the evidence for associations between commonly assessed mechanical factors and plantar heel pain, which could guide management. Plantar heel pain is associated with a higher BMI in non-athletic groups, reduced dorsiflexion range of motion, as well as reduced strength in specific foot and ankle muscle groups. There is conflicting, or insufficient evidence regarding the importance of foot alignment and first metatarsophalangeal joint range of motion. Plantar heel pain appears to be common in runners, with limited evidence for greater risk being associated with higher mileage or previous injuries. Conflicting evidence exists regarding the relationship between work-related standing and plantar heel pain, however, longer standing duration may be associated with plantar heel pain in specific worker groups. The evidence presented has been generated through studies with cross-sectional designs, therefore it is not known whether any of these associated factors have a causative relationship with plantar heel pain. Longitudinal studies are needed to ascertain whether the strength and flexibility impairments associated with plantar heel pain are a cause or consequence of the condition, as well as to establish activity thresholds that increase risk. Intervention approaches should consider strategies that improve strength and flexibility, as well as those that influence plantar fascia loading such as body weight reduction, orthoses and management of athletic and occupational workload.     

足横弓三维形态的生物力学意义

目的：通过对足横弓放松和负重状态时的三维形态分析，结合５个跖骨头在后跟略离地和抬起时的负重分布，探讨足横弓形态生物力学意义。材料和方法：在前足放松和负重状态下对５个跖骨进行ＣＴ连续横断扫描，而后在ＣＴ工作站上进行图像三维重建，在三维重建图像上观察足横弓形态变化。另外利用压敏片法测量足底５个跖骨头和趾在足跟略离地面、足跟完全抬起时的负重分布。结果：足横弓负重后有不同程度的弧度压低，但多仍保持一定的弧度；足跟略离地时中央跖骨头负重比例小于两侧跖骨头，而在足跟完全抬起时负重明显增大。结论：组成足横弓的５个跖骨头均是重要的负重结构，它们在不同的步态时相均匀地承担不同比例的重量