Is There a Role for Preoperative CT Scans in Evaluating the Posterior Malleolus in Ankle Fracture- Dislocations?

Category: Trauma Introduction/Purpose: Ankle fractures are common injuries and have a wide variety of fracture patterns. There is a high incidence of posterior malleolar fragments with ankle fracture-dislocations. There has been increasing interest in the role of the posterior malleolus in the treatment of ankle fractures. Controversies still exist on the operative indications and best method of fixation for these injuries. The current study evaluates the role of preoperative CT scans in evaluating and treating posterior malleolar fractures in this injury pattern. Methods: At our institution we initiated a protocol of obtaining post reduction computed tomography (CT) scans for all ankle fracture-dislocations with an associated posterior malleolus (PM) fractures to evaluate the fracture pattern and its role in determining operative treatment. The CT scans were evaluated for number of fragments, loose intra-articular fragments or impacted fragments, and displacement. Displacement was measured as the maximum distance noted on axial, sagittal, or coronal images. Information obtained from the CT scans was compared to the preoperative plain radiographs. Also, the authors evaluated the use of CT scans in preoperative planning with respect to positioning and surgical incisions. Results: A total of 51 ankle fracture dislocations with posterior malleolar fractures were evaluated. The size of the PM fracture measured on lateral radiographs was 24.19% compared 25.19%(p=0.75) based on the CT scan. Preoperative CT scans were able to identify loose or impacted intra-articular fragments in 19/51 cases (37%) that were not seen on plain radiographs. Multifragmentary (>2 fragments) PM fractures not appreciated on plain radiographs were found in 18 patients (35%). A total of 20 (39%) fractures were approached using direct posterior surgical exposures. The surgical plan was altered in 31% of patients based on the CT scan. Overall, PM fractures treated with direct reduction had significantly less residual displacement than those treated through indirect reduction techniques (0.4mm v 1.13mm; p=0.04). Conclusion: Posterior malleolar fractures in the setting of ankle fracture-dislocations can have complex patterns. While the overall size of posterior fragment was similar on plain radiographs and CT scan, the CT offered improved evaluation of the pattern in terms of multiple or loose intra-articular fragments. This had a direct impact on the surgical technique and approach. Improved reductions were also seen with direct posterior approaches

Surgical Trends in the Treatment of Acute Achilles Ruptures

Category: Sports Introduction/Purpose: Historically, nonoperative treatment of acute Achilles tendon ruptures was felt to have significant re-rupture rates. With improved functional rehabilitation, recent studies have shown decreased rates of tendon re-rupture. Recent randomized control trials circa 2010 have shown no difference in re-ruptures between early functional rehabilitation and surgical repair. The goal of this study was to evaluate trends in surgical treatment of Achilles ruptures, based on data obtained from the American Board of Orthopaedic Surgery (ABOS), in response to evolving level I evidence. Methods: All operative cases submitted by part II applicants from 2003 to 2015 for primary board certification by the American Board of Orthopaedic Surgery (ABOS) were retrospectively reviewed. Isolated primary Achilles tendon repairs for acute ruptures were identified by ICD-9 and CPT code. Surgeon information including fellowship training and geographic region, and patient information including age, sex, and complications were collected. Results: Out of 1,118,457 cases, there were 4792 Achilles repairs (0.43%) with 510 complications (10.6%). The rate of Achilles repairs increased from 2006 to 2010, when rates peaked at 0.57% of all collected cases (Figure 1). Since 2010, there has been a decrease in rates back to pre-2006 values. The changing rates appear to be largely driven by non-fellowship trained orthopaedic surgeons. The rates of sports and foot and ankle fellowship trained surgeons had mild increases in 2006 and decreases in 2010, but overall have slightly increased. The rate for patients greater than 65 have decreased from 2002 to 2004. Since then, there have been yearly variations, with minimal overall change. Examination of regional differences demonstrate the greatest change in the Northeast. All regions had increased rates in 2006 and decreased rates in 2010, with the exception of the Northwest and South regions, who showed little overall change. Conclusion: Surgical trends for Achilles ruptures corresponded closely to high impact level 1 publications in the literature in 2005 and 2010, suggesting evidence-based responsiveness in newly trained orthopaedic surgeons. These trends are less pronounced in the Northwest and South regions and for sports and foot and ankle specialists

Percentage of Articular Surface Debridement is Equivalent in Arthroscopic and Open Ankle Fusions

Category: Ankle Arthritis, Arthroscopy Introduction/Purpose: Tibiotalar arthrodesis is a reliable option in the treatment of end-stage ankle arthritis and both open and arthroscopically assisted techniques are well described. When compared head to head, multiple studies have demonstrated advantages of arthroscopic arthrodesis over open fusions including decreased morbidity, and shorter hospital stays while achieving equivalent or increased rates of fusion. It is unclear why arthroscopic fusion may be favorable to open surgery, however, it is hypothesized that patient selection and soft tissue trauma may play a role. No study, however, has evaluated the extent of articular debridement afforded by each technique. The purpose of this study was to evaluate the amount of articular cartilage denuded via open arthrodesis and via arthroscopic arthrodesis with time of procedure evaluated as a secondary measure. Methods: Six matched sets of fresh frozen cadaver lower extremities were acquired for study. One limb from each set was randomly assigned to open articular debridement while the other limb was assigned to arthroscopic debridement. The duration of each procedure was timed. The tibiotalar joints were disarticulated following debridement and the talus was dissected free of all soft tissue attachments. Photographs of the weight bearing portion of the articular surfaces were then taken and residual cartilage was mapped using ImageJ software. The percentage of the joint debrided was determined by the area of denuded bone divided by the total area of the articular surface to allow for comparison across specimens. The mapping process was blinded to the type of debridement undertaken. Repeated measurements were taken to determine intra- and inter-reliability of the measurements. Student t-tests were used to compare the percentage of joint debrided and differences in time of the procedure. Results: The average percentage of cartilage debrided in the arthroscopic procedure was 88.99+11.19% for the tibial plafond and 88.84.08+5.45% for the talar dome. For the open procedure, 82.93+6.91% of the tibial plafond was debrided and 84.08+5.45% of the talar dome was debrided. There were no significant differences of the tibia or talus between the open and arthroscopic procedures (p>0.05). Inter- and intra-reliability were calculated for all measurements with r>.8. There was a significant difference in the time of the procedure with the arthroscopic debridement taking 50.17+5.57 minutes to complete while the open debridement took 30.67+5.16 minutes to complete (p<0.01). Conclusion: There were no differences in the percentage of articular surface debrided when comparing arthroscopic versus open arthrodesis of the ankle joint in cadaver specimens. The arthroscopic debridement took significantly longer, however this difference may be offset by a decrease in time required for wound closure. Furthermore, an increased time of debridement may be warranted if it results in decreased wound complications and pain. The results of this study support previous clinical findings that arthroscopic debridement can yield fusion rates comparable to, or better, than open debridement of the ankle joint

Peritalar Kinematic Changes Associated with Increased Spring Ligament Tear in Cadaveric Flatfoot Model

Category: Hindfoot Introduction/Purpose: Adult Acquired Flatfoot Deformity (AAFD) is a complex and progressive deformity characterized by abduction of the midfoot and valgus alignment of the hindfoot. Spring ligament tear is often present in advanced stages of the AAFD. Previous anatomic studies have demonstrated that the superficial deltoid ligament blends with the superomedial spring ligament to provide both medial tibiotalar and talonavicular stability aiding in coronal plane stability. Given that the spring ligament blends with the superficial deltoid ligament, we sought to investigate the kinematic effect of spring ligament tear in development of peritalar instability in cadaveric flatfoot model. We hypothesized that increased spring ligament tear size will result in increased talonavicular joint abduction (axial) and plantarflexion (sagittal), and increased valgus alignment of the tibiotalar and subtalar joints (coronal). Methods: Seven fresh-frozen cadaveric foot specimens were employed. Reflective markers were mounted on the tibia, talus, navicula, calcaneus and the first metatarsus. Kinematics of the peritalar joints were captured by multiple camera motion capture system. A flatfoot model was created by sectioning the medial and inferior talonavicular interosseous ligament, followed by cyclic axial load of 1150 N under a hydraulic loading frame with 350 N load applied to the Achilles tendon. The talo-first metatarsus (T- 1MT) abduction angle was calculated and cycles were applied until abduction of 5-10° (mild flatfoot) was achieved. Spring ligament sectioning was extended 1 cm proximally along the superomedial ligament followed by cyclic loading until 10-15° (moderate) of T- 1MT abduction was achieved. The spring ligament was sectioned for another 1 cm followed by cyclic loading until >15° (severe) abduction was noted. The relative kinematic changes were compared among the initial, mild, moderate, and severe flatfoot model using two-way ANOVA. Results: The average T-1MT abduction angles in the mild, moderate, and severe flatfoot were 7.79°+/-2.27°, 11.47°+/-2.82°, and 15.46°+4.15°. Meary’s angle increased with progression of the flatfoot (mild 6.17°+/-2.92°, moderate 9.71°+/-3.4°, severe 12.46°+/-4.13°). Hindfoot valgus angle also increased. The mild, moderate, and severe flatfoot showed 2.4°+/-3.85°, 4.13°+/-3.9°, and 4.75°+/-3.79° of tibiotalar valgus angle. The subtalar joint exhibited 2.94°+/-3.41°, 5.52°+/-4.34°, and 6.97°+/-4.83° valgus angle in the mild, moderate, and severe models. The T-1MT abduction angle and Meary’s angle were significantly different in all flatfoot models compared to the initial condition (p<0.001), and the severe vs. mild models (p<0.01). Tibiotalar valgus was significantly increased in severe compared to the initial model (p=0.02). Subtalar valgus angle significantly increased in the moderate and severe models compared to the initial (p<0.01, p<0.001). Conclusion: Serial increment in spring ligament tear size in simulated flatfoot increased relative talus adduction and plantarflexion. It also resulted in gradual increment of valgus alignment of the tibiotalar and subtalar joints in coronal plane. This finding demonstrates that a large spring ligament tear in advanced stage AAFD leads to increased strain across the medial peritalar ligaments. In addition to osseous correction and tendon transfer, medial ligament augmentation, may be a critical component in surgical correction of AAFD with a large spring ligament tear

Trends in PROMIS Scores in the Early Post-operative Period following Various Lateral Ankle Ligament Reconstructive Techniques

Category: Sports Introduction/Purpose: Lateral ankle ligament injuries are common conditions accounting for 25% of musculoskeletal injuries. When conservative management fails and chronic instability ensues, operative treatment is often sought. Though surgical outcomes are generally good following lateral ankle ligament reconstruction, literature suggests current scoring systems for evaluating outcomes and monitoring progression have deficiencies. Patient Reported Outcomes Measurement Information (PROMIS) scores have recently been established as a method of monitoring patient outcomes. The purpose of this study was to evaluate the trends in post-operative PROMIS physical function (PF), pain interference (PI), and depression scores in patients undergoing lateral ankle ligament reconstruction. Methods: PROMIS scores were prospectively obtained from all patients evaluated in our foot and ankle clinic between February 2015 and October 2016. Using ICD-9/10 and CPT codes, a total of 111 patients who underwent lateral ankle ligament reconstruction were identified. After meeting exclusion criteria (less than three-month follow-up, incomplete PROMIS scores or multiple surgeries), 55 patients were included. PROMIS PF, PI, and depression were evaluated at each post-operative visit. Changes in scores were calculated as compared to baseline pre-operative scores and compared at each follow-up time point using two-way ANOVA. Differences in reconstruction type in patients undergoing allograft (A), modified Broström-Gould (BG), or modified Broström-Gould augmented with fibertape (BG+FT) were also evaluated. Results: The average follow-up was 27.05 weeks (range 12-60.1 weeks). 11 patients had > 9 months follow-up. Changes in PF were significantly different from baseline at all time-points except for 8-12 week follow-up. PF was significantly worse at 2 and 4-6 week follow-up, and significantly better at >12 weeks follow-up (p12 weeks. PI scores were significantly improved from baseline beginning at 4 weeks follow-up. Depression scores also significantly improved at 8-12 weeks follow-up. BG+FT showed a trend of slower improvement in PF, though not significant. Though longer follow-up is needed, the significant improvements in PF, PI, and depression following lateral ankle ligament reconstruction in our study provides data that can be used for pre-operative counseling and monitoring progression post-operatively

Tibiocalcaneonavicular Ligament Reconstruction in Simulated Flatfoot Deformity with Medial Ligament Insufficiency

Category: Hindfoot Introduction/Purpose: Spring ligament tear is often present in advanced stages of the AAFD. Anatomic studies have demonstrated that the superficial deltoid ligament blends with the superomedial spring ligament to provide medial tibiotalar and talonavicular stability. Reconstruction of combined deltoid-spring ligament, or the Tibiocalcaneonvaicular ligament (TCNL) was proposed to augment medial stability in advanced AAFD with large spring ligament tears. A tendon allograft is placed to cross three peritalar (tibiotalar, talonavicular and subtalar) joints to augment medial stability. We aimed to 1) investigate the kinematic effects of TCNL reconstruction in cadaveric flatfoot model with medial ligament insufficiency, and 2) compare TCNL reconstruction with anatomic spring and anatomic deltoid ligament reconstructions (Figure 1). We hypothesized that TCNL reconstruction is effective in restoring peritalar kinematics. Methods: Five fresh-frozen cadaveric foot specimens were employed. Advanced stage flatfoot model was created by sectioning the medial and inferior talonavicular interosseous ligament and extending the release 2 cm proximally along the superomedial spring ligament. Cyclic axial load of 1150 N under a hydraulic loading frame with constant 350 N Achilles tendon load were applied until >15° talo-first metatarsal abduction was achieved. Bone tunnels were drilled for three reconstruction types, and the peroneus longus tendon was configured to reconstruct the 1) anatomic spring ligament, 2) anatomic deltoid ligament, and 3) TCNL. Reflective markers were mounted on the tibia, talus, navicula, calcaneus and first metatarsus. Each reconstruction type was loaded with 800 N ground reaction force, and kinematics of the peritalar joints were captured by 4-camera motion capture system. Forefoot abduction angle, Meary’s angle, and hindfoot valgus were calculated and compared to the severe flatfoot prior to reconstruction and to each using two-way ANOVA. Results: In creating the flatfoot deformity, both the tibiotalar and subtalar joints demonstrated an increase in valgus deformity by 5.6+3.7° and 6.1+5.3°, respectively, compared to the initial measurements. When comparing to the flatfoot deformity, the TCNL reconstruction achieved a significant improvement in percent correction of total hindfoot valgus (59.7+21.1%, p=0.017) and forefoot abduction angle (83.4+17.7%, p<0.01). The spring ligament reconstruction also demonstrated a significant improvement in forefoot abduction correction compared to the flatfoot (52+10.6%, p<0.05). No other reconstruction technique achieved a statistically significant improvement in percent correction compared to the flatfoot model in forefoot or hindfoot alignments. Additionally, no statistical differences were noted in the percent correction when comparing the three reconstructive techniques to each other. Conclusion: In advanced stage cadaveric flatfoot with spring ligament tear, we found increased valgus alignment at both the tibiotalar and subtalar joints. This kinematic changes reflects increased strain across the medial peritalar ligaments. The deltoid-spring ligament complex (TCNL) reconstruction demonstrated significantly improved alignment of hindfoot valgus and forefoot abduction compared to the severe flatfoot condition. This finding suggests that in addition to osseous correction and tendon transfer, the TCNL reconstruction may serve as an important component in augmenting medial stability in advanced AAFD with medial ligament insufficiency

A Novel Method for Measurement of Ankle Joint Reaction Force and Response to Syndesmotic Injury

Category: Ankle. Introduction/Purpose: Increasing evidence has suggested that alterations in joint mechanics results in articular pathology. Previous studies demonstrated noninvasive measurements of joint reactive forces (JRF) can be performed reliably without destruction of the peri-articular soft tissue in medium and small size joints of the upper extremity. This study presents a novel, noninvasive measurement of the JRF to investigate the normal and the effects of a syndesmotic injury. The JRF of the tibiotalar joint was also evaluated following anatomic reduction with fixation and malreduction of the syndesmosis. Methods: Eight fresh-frozen human cadaveric lower extremity limbs were obtained disarticulated above the knee. A distraction force was applied across the tibio-talar joint to determine the baseline (normal) ankle force displacement curve. Next, a syndesmotic injury was created by releasing the interosseous syndesmotic ligaments, the transverse tibiofibular ligament and the anterior and posterior tibiofibular ligaments. Prior to sectioning, two drill holes were placed across the joint and tapped to ensure anatomic reduction. JRF were measured using a quadricortical technique with a single or double screw configuration. The syndesmosis was malreduced by anteriorly displacing the fibula 5 mm. After each step, the resultant JRFs were determined using a distraction force across the tibiotalar joint. Results: Force displacement curves obtained from multiple measurements from each specimen with a mean ankle JRF of 31.4 + 2.6 N. Syndesmotic injury resulted in a 35% decrease in tibiotalar JRF (20.3 + 3.0 N, p=0.002). Fixation of the injury using one syndesmotic screw resulted in significant increase in JRF compared to injury JRF (28.7 + 1.4 N, p=0.02). Syndesmotic fixation with 2 screws also demonstrated a trend towards restoration of tibiotalar JRF (28.3 + 2.2 N, p=0.06). There was no statistical difference between fixation of one versus two syndesmotic screws. The JRF for the malreduced syndesmosis was 31.5 + 1.8 N (p=0.03,) resulting in increased forces approaching the baseline JRF. Conclusion: This study demonstrates a non-destructive model by which to measure joint reactive forces (JRF) across the tibiotalar joint and that these forces are diminished as a result of a syndesmotic injury, suggesting joint instability. Surgical stabilization with either 1 or 2 screws creates JRF that are similar to the normal JRF. Even with a malreduced syndesmosis, there appeared to be a JRF similar to baseline tibiotalar joint forces. However malreduction of the syndesmosis may alter the joint dynamics of the ankle in ways that were not measured in this study

When are the Patients Satisfied with Their Outcome? Correlation of PROMIS Values with Patient Acceptable Symptom State (PASS) Scores in Foot and Ankle Patients

Category: Outcomes Introduction/Purpose: PROMIS values are being adopted due to ease of use and influence on clinical decision making. Studies support the use of PROMIS physical function (PF), pain interference (PI), and Depression (D) for pre-surgical decision making. Patient Acceptable Symptom State (PASS) is a validated outcome measure commonly used in other areas of medicine and surgery that captures when patient’s symptoms reach a daily acceptable level. Knowing what PROMIS scores are associated with a patient’s PASS(Yes)/(No) rating would further enhance the use of PROMIS scales. The purpose of this study: 1) association of PROMIS scales with a PASS rating, 2) threshold values of PROMIS PF, PI, D associated with PASS rating, and 3) whether PROMIS, and patient demographics are predictive of a PASS rating. Methods: 464 consecutive foot and ankle patients (variety of foot and ankle conditions) over a 4 week interval prospectively completed PROMIS PF, PI and D as well as the PASS question: “Taking into account all of the activities that you do during your daily life, your level of pain, and also your function, do you consider that the current state of your foot and ankle is satisfactory?” PROMIS assessments are used as the standard of care however, the point patients feel they have improved to an acceptable degree (PASS) is not known. The analysis included 1) a two-way ANOVA to compare PROMIS scores (PF, PI, D) between patients grouped as PASS(Yes) and PASS(No); 2) ROC analysis to determine AUC, cut offs, and 95% sensitivity/specificity for PASS(Yes), PASS Ambiguous, and PASS(No); 3) Logistic regression analysis with PROMIS scales, age, gender, and visit type as predictors and PASS(Yes)/(No). Results: PROMIS PF was lower (p<0.01) and PI higher (p<0.01), however, PROMIS D (p=0.26) was similar between PASS(Yes/No) groups. The AUC for PROMIS PF(p<0.01) and PI(p<0.01) were significant but not PROMIS D (p=0.21). The cut offs for PASS(Yes) with 95% specificity were 52.0 and 50.7 for PF and PI, respectively. The cut offs for PASS(No) with 95% sensitivity were 23.6 and 69.6 for PF and PI, respectively. PROMIS values between 23.6 and 52 for PF and between 50.7 and 69.6 for PI were PASS ambiguous. Regression analysis showed that gender, visit type, and PROMIS (PI/PF) significantly predicted PASS(Yes)/(No) (75% accuracy). Conclusion: PROMIS t-scores of near 50 (average of US population) correspond to PASS(Yes) cut offs for both PF and PI. When feasible a benchmark of 50 on PROMIS T-scores may be a reasonable goal for patient outcome after foot and ankle treatments. For patients that are PASS ambiguous, other factors such as preoperative PROMIS scores (PF and PI), gender, and visit type (new or follow up) may motivate discussions with patients about their expectations of treatment. Longer term follow-up, may result in a higher percentage of PASS YES patients and alter cut off scores

Do PROMIS Scores Show That Nonoperative Treatment of Achilles Tendonopathy Works?

Category: Ankle, Sports Introduction/Purpose: Achilles tendonopathy (AT), whether insertional (IAT) or non-insertional (NIAT), is a common clinical disorder. Operative and nonoperative care have been evaluated, although often employing non-validated measures. In addition, it is common for AT response to be reported without separating IAT versus NIAT. This adds to uncertainty regarding expected improvement in patients presenting for treatment with AT. There is a paucity of literature analyzing nonoperative treatment of IAT and NIAT as distinct entities using patient-reported outcomes. We utilize Patient-Reported Outcomes Measurement Information System (PROMIS) Physical-Function (PF), Pain-Interference (PI) and Depression (D) domains to determine clinical response to nonoperative treatment in all AT patients. We further compared clinical response in patients with IAT to patients with NIAT. Methods: Patient visits to an academic orthopaedic foot and ankle center over an 18 month period (March 2015 to October 2016) were prospectively collected. All patients with AT were determined using ICD-9 codes, and they were stratified between IAT and NIAT. Only patients with complete PROMIS scores (PF, PI and D) at both presentation as well as following a course of nonoperative care, including heel lifts and an achilles/gastrocnemius stretching and strengthening program, were included for analysis. A total of 102 patients fit our inclusion criteria, with an average follow up of 68 days. Based on a distribution-based method, the minimum clinically important difference (MCID) was set at one-half standard deviation. Overall descriptive statistics were determined for all patients. Bivariate analysis was conducted to compare NIAT and IAT patients across a wide range of variables. Significance was set at 0.05 for all analyses. Results: Fifteen (46%), 12 (36%) and 9 (27%) patients with NIAT reached MCID for PF, PI and D, respectively. Eleven (33%) patients with NIAT reached MCID in both PF and PI. Seventeen (25%), 20 (29%) and 22 (32%) patients with IAT reached MCID for PF, PI and D, respectively. Six (9%) patients with IAT reached MCID in both PF and PI. A larger percentage of men had NIAT (63.6% vs. 36.2%; p = 0.009), while a larger percentage of women had IAT (63.8% vs. 36.4%; p = 0.009). Changes in PROMIS PF scores were higher in patients with NIAT (4.0 vs. -0.046; p = 0.035). A higher percentage of patients with NIAT reached MCID in PF (45.5% vs. 24.6%; p = 0.034). Conclusion: A considerable portion of patients with AT respond favorably to nonoperative care. PROMIS scores did not vary at presentation between IAT and NIAT, yet between 25% and 46% of patients in each subgroup reached MCID in at least one domain. Although a higher percentage of patients with NIAT reached MCID, patients with IAT also demonstrated MCID improvement. Using PROMIS for disease specific pathologies and nonoperative treatment in foot and ankle care provides clinical value previously uncaptured. Our results demonstrate nonoperative treatment for AT has clinical utility and economic value in a time of increased scrutiny on healthcare spending

Noninvasive Measurement of Normal Foot and Ankle Joint Reaction Force

Category: Basic Sciences/Biologics Introduction/Purpose: Various biomechanical studies have examined pressure changes across the foot and ankle joints. However, most of these studies disrupted the capsuloligamentous complex surrounding the joint to insert pressure sensors, compromising the integrity of the natural joint structure and the accuracy of biomechanical assessments. This is the first noninvasive study to report measurement of natural joint reaction forces (JRF) across the foot and ankle while preserving all soft tissue structures. Since articular surfaces experience equal and opposing compression forces, we aimed to evaluate the distraction force needed to overcome these compression forces. Methods: Ten fresh-frozen cadavers of the lower extremity were obtained that were disarticulated at the knee joint. Steinmann pins were percutaneously placed across the distal tibia, and the center of the talus, navicular, cuboid, and calcaneus while preserving all surrounding soft tissues. A custom fixation device was utilized in conjunction with a tensile testing machine to allow distraction in line with the axis of the tibiotalar, subtalar, talonavicular (TN), and calcaneocuboid (CC) joints. Displacement was measured as distance between Steinmann pins on either side of the joint examined. Under progressive axial distraction, displacement and force were measured. Best-fit polynomials were calculated to fit the force-displacement curves. The inflection point, representing the joint reaction force (JRF) where distraction forces across the joint equal the compression forces, was calculated for each curve. Results: All force-displacement curves demonstrated an inflection point. Prior to the inflection point, relatively large increases in distraction force resulted in minimal displacement. Once the inflection point was reached, relatively small increases in distraction force resulted in large increases in displacement. Each cadaver was measured three times with high reproducibility. The mean JRF were tibiotalar 33.8 N [standard deviation (SD) 10], subtalar 18.2 N (SD 12), TN 13.3 N (SD 4), and CC 14.7 N (5.8). Conclusion: We present the first application of a reliable and noninvasive method of measuring JRF of the foot and ankle joints. In the medium or small joints, dissection of the capsule and surrounding ligaments can significantly alter joint stability and biomechanics. By preserving all the periarticular soft tissues, this experimental model will allow future investigation of biomechanical changes of pathologic states and efficacy of surgical intervention under conditions that most accurately reflect the in vivo state