Loss of Mechanical Ankle Function Is Not Compensated by the Distal Foot Joints in Patients with Ankle Osteoarthritis.

BACKGROUND: Patients with isolated ankle osteoarthritis (OA) often demonstrate disturbed ankle biomechanics during walking. Clinicians often believe that this triggers the distal foot joints to compensate these altered ankle biomechanics and that these foot joints are consequently subjected to degenerative joint diseases due to overuse. QUESTIONS/PURPOSES: Do patients with isolated ankle OA differ from those without ankle OA in terms of (1) ankle and foot joint kinematics and (2) ankle and foot joint kinetics as measured using three-dimensional (3-D) gait analysis? (3) Do these patients demonstrate compensatory strategies in their Chopart, Lisfranc, or first metatarsophalangeal joints in terms of increased joint kinematic and kinetic outputs? METHODS: Between 2015 and 2018, we treated 110 patients with unilateral ankle OA, and invited all of them to participate in the gait analysis laboratory. Of those, 47% (52) of patients did so, and of these, 16 patients met the inclusion criteria for this study, which were (1) diagnosis of unilateral ankle OA; (2) absence of radiographical signs of OA in the contralateral foot or lower limbs; (3) ability to walk at least 100 m without rest; and (4) being older than 18 years of age. A control group (n = 25) was recruited through intranet advertisements at the University Hospitals of Leuven. Participants were included if their age matched the age-range of the patient group and if they had no history of OA in any of the lower limb joints. Patients were slightly older (55.9 ± 11.2 years), with a slightly higher BMI (28 ± 6 kg/m2) than the control group participants (47.2 ± 4.4 years; p = 0.01 and 25 ± 3 kg/m2; p = 0.05). All participants underwent a 3-D gait analysis, during which a multisegment foot model was used to quantify the kinematic parameters (joint angles and ROM) and the kinetic parameters (rotational forces or moments), as well as power generation and absorption in the ankle, Chopart, Lisfranc, and first metatarsophalangeal joints during the stance phase of walking. Peak values were the maximum and minimum values of waveforms and the latter were time-normalized to 100% of the stance phase. RESULTS: Regarding joint kinematics, patients demonstrated a sagittal plane ankle, Chopart, Lisfranc, and first metatarsophalangeal joint ROM of 11.4 ± 3.1°, 9.7 ± 2.7°, 8.6 ± 2.3° and 34.6 ± 8.1°, respectively, compared with 18.0 ± 2.7° (p < 0.001), 13.9 ± 3.2° (p < 0.001), 7.1 ± 2.0° (p = 0.046) and 38.1 ± 6.5° (p = 0.15), respectively, in the control group during the stance phase of walking. With regard to joint kinetics in the patient group, we found a mean decrease of 1.3 W/kg (95% CI confidence interval 1.0 to 1.6) (control group mean: 2.4 ± 0.4 W/kg, patient group mean: 1.1 ± 0.5 W/kg) and 0.8 W/kg (95% CI 0.4 to 1.0) (control group mean: 1.5 ± 0.3 W/kg, patient group mean: 0.7 ± 0.5 W/kg) of ankle (p < 0.001) and Chopart (p < 0.001) joint peak power generation. No changes in kinetic parameters (joint moment or power) were observed in any of the distal foot joints. CONCLUSION: The findings of this study showed a decrease in ankle kinematics and kinetics of patients with isolated ankle OA during walking, whereas no change in kinematic or kinetic functions were observed in the distal foot joints, demonstrating that these do not compensate for the mechanical dysfunction of the ankle. CLINICAL RELEVANCE: The current findings suggest that future experimental laboratory studies should look at whether tibiotalar joint fusion or total ankle replacement influence the biomechanical functioning of these distal joints.

Analysis of Micromotion in a Talonavicular Arthrodesis With and Without a Calcaneal Displacement Osteotomy in a Cadaver Model.

The isolated talonavicular joint arthrodesis can be beneficial to correct midfoot deformities involving the talonavicular joint, including collapsing pes planovalgus. Studies show that isolated talonavicular arthrodesis has a higher nonunion rate because of micromotion; thus, other procedures should be used in conjunction with it. We sought to determine if adding an adjunctive medial calcaneal displacement osteotomy helps to reduce the ground reactive force and, therefore, the micromotion on the talonavicular joint. We used 4 below-knee limbs to study the force placed on the joint in an isolated talonavicular arthrodesis compared with the same procedure with an adjunctive calcaneal osteotomy under weightbearing simulation. A 0.5-inch circular force sensing resistor was placed within the talonavicular and used to check the force on the joint after a 5-lb force was added to the proximal limb. The resistance was quantified with force measured as a direct inverse. This procedure was performed 3 times for each limb. The mean resistance before and after calcaneal osteotomy was analyzed with use of the paired t test. In the pre-calcaneal osteotomy sites, the mean resistance given in 200 kΩ was 388.2 ± 565.9 compared with 1016.6 ± 482.7 in the post-calcaneal osteotomy sites (p = .02). Findings from this cadaver study indicate reduction in forces to the talonavicular joint with an adjunctive calcaneal osteotomy. We conclude that it can be a beneficial adjunctive procedure for patients at a high risk of nonunion, such as those with obesity or diabetes or those who smoke. These patients could benefit from the decreased micromotion that the adjunctive procedure allows.

The effect of extra-osseous talotarsal stabilization (EOTTS) to reduce medial knee compartment forces - An in vivo study.

BACKGROUND: Excessive hindfoot pronation, talotarsal joint (TTJ) instability, has been attributed to an increase in medial knee compartment pathology. Advocacy for hindfoot realignment has been the subject of research. An internal solution for TTJ instability, extra-osseous talotarsal stabilization (EOTTS), exists but its effect on knee forces is unknown. This is the first study to measure the in vivo forces acting within the medial knee compartment before and after EOTTS. We hypothesized that following EOTTS there should be a reduction of force acting on the medial knee compartment. METHODS: 10 fresh frozen cadaver lower extremities exhibiting clinical and radiographic evidence of TTJ instability were evaluated. The proximal femur segment was mounted to a mechanical testing unit. Pressure sensors were placed within the medial knee compartment. A force of 1000 newtons was then applied, and the femur was internally rotated 10 degrees. Measurements were recorded before and after the insertion of a type II EOTTS stent. RESULTS: Pre-EOTTS resulted in an average of 842 ± 247N acting within the medial knee joint compartment. These forces then decreased to an average of 565 ± 260N (<0.05) following EOTTS, representing an average reduction of force by 32.8%. CONCLUSION: EOTTS has been shown to decrease the in vivo forces action within the medial knee compartment. This helps to further illustrate the importance of realigning and stabilizing the hindfoot for the prevention and treatment of chronic knee pain.

Dynamic First Tarsometatarsal Instability During Gait Evaluated by Pedobarographic Examination in Patients With Hallux Valgus.

BACKGROUND: This study aimed to investigate the pedobarographic characteristics of tarsometatarsal instability and to identify factors associated with pedobarographic first tarsometatarsal instability in patients with hallux valgus. METHODS: Fifty-seven patients (mean age, 59.7 years; standard deviation, 11.4 years; 6 men and 51 women) with a hallux valgus angle (HVA) greater than 15 degrees were included. All patients underwent a pedobarographic examination along with weightbearing anteroposterior (AP) and lateral foot radiography. Radiographic measurements were compared between the 2 groups with and without pedobarographic first tarsometatarsal instability. The association between the radiographic and pedobarographic parameters of the first tarsometatarsal instability was analyzed using the chi-square test. Binary logistic regression analysis was performed to identify significant factors affecting pedobarographic first tarsometatarsal instability. RESULTS: The HVA (P < .001), intermetatarsal angle (P = .001), and AP talo-first metatarsal angle were significantly different between the pedobarographically stable and unstable tarsometatarsal groups. There was no significant association between radiographic and pedobarographic instability of the first tarsometatarsal joint (P = .924). The HVA was found to be the only significant factor affecting pedobarographic tarsometatarsal joint instability (P = .001). CONCLUSION: The pedobarographic examination has possible clinical utility in evaluating first tarsometatarsal joint instability in patients with hallux valgus. Patients with a greater HVA should be assessed for the presence of first tarsometatarsal instability, and the necessity of the Lapidus procedure should be considered. LEVEL OF EVIDENCE: Level III, comparative study.

Complete Cuboid Dislocation With Associated Lisfranc Injury: A Case Report and Review of the Literature.

Cuboid dislocations are rare midfoot injuries that usually occur in the setting of high-energy trauma. Diagnosis can be challenging and optimal treatment remains unknown. This case report and review aims to summarize the recent literature on this topic.

Measurement of Dorsal First Ray Mobility: A Topical Historical Review and Commentary.

Despite evidence that instability of the first ray (first metatarsal and medial cuneiform) alters the loading mechanics of the foot, surprisingly few studies have linked the condition with disorders of the foot. A factor limiting this research is the difficulty associated with measuring first ray mobility (FRM). To quantify dorsal FRM, clinicians and researchers have devised a variety of methods that impose a dorsally directed load, and record displacement. The methods include manual examination, radiographs, mechanical devices, and handheld rulers. Since different methods yield different results; each of these methods is worthy of scrutiny. This article reviews the methods used to quantify dorsal FRM and offers commentary on how the testing procedures could be standardized. The measurement of dorsal FRM informs surgical decisions, orthotic prescriptions, and research design strategies mostly as it pertains to the identification and treatment of first ray hypermobility. This review found sufficient support to recommend continued use of radiographs and mechanical devices for quantifying dorsal displacement, whereas measurements acquired with handheld rulers are prone to the same subjective error attributed to manual examination procedures. Since measures made with radiographs and existing mechanical devices have their own drawbacks, the commentary recommends ideas for standardizing the testing procedure and calls for the development of a next-generation device to measure dorsal FRM. This future device could be modeled after arthrometers that exist and are used to quantify stability at the knee and ankle. Level of Evidence: Level V, expert opinion.

Derotation of the Talus and Arthrodesis Treatment of Stages II-V Müller-Weiss Disease: Midterm Results of 36 Cases.

BACKGROUND: Various operative procedures have been reported for the treatment of Müller-Weiss disease (MWD). This study reports the midterm operative treatment results for stages II to V MWD with derotation of the talus and arthrodesis. METHODS: Thirty-four patients (36 feet) with MWD were treated by talonavicular (TN) or talonavicular-cuneiform (TNC) arthrodesis in our center from 2008 to 2015. The affected feet were staged according to the Maceira staging system (stage II: 9; stage III: 10; stage IV: 9; stage V: 8). The American Orthopaedic Foot & Ankle Society (AOFAS) midfoot scale, the visual analog scale (VAS), and relative radiologic parameters were evaluated preoperatively and also during follow-up. The mean follow-up duration was 38.2 (range, 25-113 months). RESULTS: The final follow-up showed satisfactory outcomes. Overall, the AOFAS scores improved from 41.5 (range, 20-56) to 85.3 (range, 68-100) points ( P <.001), and the VAS score decreased from 5.7 (range, 3-8) to 0.9 (range, 0-4) points ( P <.001). The Tomeno-Méary angle decreased from -6.7 (range, -26.4 to 17.7) to 0.7 (range, -5.3 to 7) degrees ( P=.001). The calcaneal pitch angle increased from 13.7 (range, 4.1-26.2) to 22.0 (range, 13.3-28.9) degrees ( P < .001). The anteroposterior (AP) talar-first metatarsal angle decreased from -15.8 (range, -30.1 to -13.7) to -7.0 (range, -25.9 to -8.9) degrees ( P < .001), and the AP talocalcaneal angle increased from 14.7 (range, 4.7-22.3) to 22.1 (range, 13.4-29.5) degrees ( P=.005). The AP talonavicular coverage angle decreased from -27.0 (range, -40.4 to -13.3) to -7.8 degrees (range, -20.7 to -1.8) degrees ( P < .001). CONCLUSION: The midterm results found that the TN or TNC joint fusion could achieve a favorable clinical and radiologic outcome for patients with MWD. Even for the patients with severe deformities (stages IV-V), this treatment strategy could also achieve satisfactory deformity correction and functional improvement. Intraoperative restoration of talus rotation was the key to normal alignment of the subtalar joint/TN joint. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Spring ligament tear decreases static stability of the ankle joint.

BACKGROUND: Spring ligament tear is often found in advanced adult acquired flatfoot deformity and its reconstruction in conjunction with the deltoid ligament has been proposed to restore the tibiotalar and talonavicular joint stability. The aim of the present study is to determine the effect of spring ligament injury and subsequent reconstruction on static joint reactive force using a non-invasive method of measurement. METHODS: Ten fresh-frozen human cadaveric lower legs were disarticulated at the knee joint. Static joint reactive force of the tibiotalar and talonavicular joint were measured at baseline, after spring ligament injury, and after ligament reconstruction. Reconstruction consisted of a forked semitendinosis allograft with dual limbs to reconstruct the tibionavicular and tibiocalcaneal ligaments. FINDINGS: The mean baseline joint reactive force of the tibiotalar and talonavicular joints were 37.2 N + 8.1 N and 13.4 N + 4.2 N, respectively. The spring ligament injury model resulted in a significant 29% decrease in tibiotalar joint reactive force. Reconstruction of the tibionavicular limb resulted in a significant increase in tibiotalar and talonavicular joint reactive force compared to those seen in the injury state. Furthermore, the addition of the tibiocalcaneal limb significantly increased tibiotalar joint reactive force compared to those results obtained from the injury state and the tibionavicular limb alone. INTERPRETATION: This is the first study to demonstrate diminished tibiotalar static joint reactive force in a spring ligament injury model with subsequent joint reactive force restoration using two-limbed reconstruction of the deltoid and spring ligament. LEVEL OF EVIDENCE: Biomechanical Study.

Pathological kinematic patterns of the tarsal complex in stage II adult-acquired flatfoot deformity.

The in vivo kinematic characteristics of the tarsal joints during gait stance phase were still unclear in adult-acquired foot deformity (AAFD). This study included seven healthy subjects (14 feet) and 12 stage II AAFD patients (14 feet). The 3D models of tarsal bones were reconstructed based on CT scan. Each subject took standard gait on the single fluoroscopy system. Continuous lateral fluoroscopic images were collected. The key postures during the stance phase were selected. The 2D-3D registration technique was applied to explore the spatial motions of the tarsal joints in 6 degrees of freedom (DOF). During the whole stance phase, the AAFD talo-navicular joint (TNJ) exhibited ROM of 13 ± 6° in the sagittal plane while the normal subjects showed ROM of 7 ± 3° (p = 0.004). In AAFD, the subtalar joint (STJ) demonstrated 19 ± 8° and 7 ± 3° of motion in coronal and horizontal plane, respectively, while the normal subjects showed 14 ± 4°(p = 0.031) and 11 ± 3° (p = 0.014) of motion, respectively. Additionally STJ of AAFD patients showed significantly less dorsiflexion during the weight acceptance and showed significantly less external rotation both during the weight acceptance and single limb support of stance phase. In conclusion, for stage II AAFD patients, the talonavicular joint and the subtalar joint showed hypermobility in dorsi/planterflexion and inversion/eversion, respectively, during the gait stance phase while the internal/external rotation of the subtalar joint was reduced. The current study improves our understanding of the pathological kinematics of the tarsal complex in AAFD patients. Notice should be taken about these tarsal joints mobility in AAFD during clinical practice. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:477-482, 2019.

Arthroscopic Medial Approach for Modified Double Arthrodesis of the Foot.

The single medial incision subtalar joint and talonavicular joint arthrodesis has been shown to be a useful alternative for the correction of hindfoot valgus deformity. We describe an arthroscopic method of joint preparation using this approach. The present case report included 6 consecutive patients aged 35 to 72 (mean ± standard deviation 55.8 ± 15.54) years (4 males [66.7%] and 2 females [33.3%]), who had undergone the medial approach for modified double arthrodesis of the foot. Of the 6 patients, 3 (50.0%) had undergone arthroscopic joint preparation and 3 (50.0%) traditional (manual) joint preparation. Osteobiologic agents were used in all patients. We found a shorter tourniquet time for the patients who had undergone an arthroscopic approach, with a mean of 110 ± 7.21 minutes, compared with a traditional joint preparation, with a mean of 121.3 ± 8.08 minutes. We also found a shorter time to radiographic union in the patients who had undergone an arthroscopic approach, all of whom showed signs of union at 6 weeks. Only 2 of the 3 patients in the traditional joint preparation group had achieved union at a mean of 10 ± 2.83 weeks, with 1 case resulting in nonunion. This technique could be a viable alternative to traditional methods of joint preparation by decreasing the operative time and improving the union rates.

Dual Window Approach With Two-Side Screw Fixation for Isolated Talonavicular Arthrodesis.

Isolated talonavicular arthrodesis is a commonly performed surgical intervention. Nonunion is a dreaded complication. The aim of the present study was to analyze the clinical and radiologic outcome of talonavicular arthrodesis using a dual approach with 2-side screw fixation. From February 2012 to September 2014, isolated talonavicular arthrodesis was performed on 17 joints of 16 patients (mean age 59.12 years). All procedures were performed by a single surgeon. The incidence of union, visual analog scale scores, and complications were analyzed. Radiographic union was achieved in all 17 cases (100%) at a mean period of 13.12 weeks. The visual analog scale scores had improved significantly (p < .001) at a mean follow-up of 48.53 weeks. One patient (6%) had minimal wound problems, and one (6%) showed prolonged swelling postoperatively. We have concluded that the dual window approach with 2-side screw fixation for isolated talonavicular arthrodesis results in excellent clinical and radiographic results and high fusion rates.

Tarsometatarsal (Lisfranc) Joint Injury in an Athlete With Persistent Foot Pain.

The patient was a 20-year-old female ultimate frisbee player who felt a "pop" in her left foot with resultant pain and bruising along the plantar aspect of her midfoot. She was seen by an orthopaedic physician, who ordered standard radiographs that were found to be unremarkable. Although initial non-weight-bearing films were normal, these findings do not rule out tarsometatarsal joint injury. Following presentation to physical therapy 4 months after the initial injury, the patient was referred to a sports medicine physician. Weight-bearing radiographs and magnetic resonance imaging were ordered and confirmed a high-grade Lisfranc ligament tear. J Orthop Sports Phys Ther 2016;46(6):494. doi:10.2519/jospt.2016.0408.

Foot orthoses in the management of chronic subtalar and talo crural joint pain in rheumatoid arthritis.

BACKGROUND: This pilot study investigated whether semi-rigid and soft orthoses had an effect on pain, disability and functional limitation in participants with chronic rheumatoid hindfoot involvement. METHODS: Participants with chronic hindfoot pain were randomly assigned to 2 groups, commencing either with semi-rigid Subortholene orthoses or soft EVA orthoses. The Foot Function Index and the Ritchie Articular Index were administered pre- and post-intervention, which lasted for 3 months. Following a 2 week washout period, each group was switched over to the other type of orthoses. RESULTS: Nine female participants (mean age 52.2years (SD 9.1); mean weight 71kg (SD 12.64); mean height 160cm (SD 5.18)) with a mean RA duration of 11.7years (SD 7.83), and a mean ankle/subtalar joint pain duration of 5.7years (SD 2.62), completed the programme. Mean improvement in FFI score for both orthoses resulted in the same statistical significance (p=0.001). Statistically significant reduction in pain, disability and functional limitation was observed for both interventions, together with improvement in the Ritchie Articular Index score. CONCLUSION: Both Subortholene and EVA orthoses significantly reduced pain, disability and functional limitations in participants with chronic ankle/subtalar joint pain in rheumatoid arthritis.

Effects of the neutrophil elastase inhibitor EL-17 in rat adjuvant-induced arthritis.

OBJECTIVES: Neutrophil elastase (NE), a granule-associated enzyme, participates in connective tissue breakdown and promotes cytokine release and specific receptor activation during various inflammatory diseases like RA. NE is increased in the SF and cartilage of RA patients and represents a target for the development of new therapeutic possibilities. The present research aimed to evaluate the preclinical pharmacological profile of the N-benzoylpyrazole derivative EL-17, a potent and selective NE inhibitor, in a rat model of RA. METHODS: Complete Freund's Adjuvant (CFA) was injected in the tibiotarsal joint and the effect of acute or repeated treatments with EL-17 (1-30 mg/kg by mouth) were evaluated. RESULTS: On day 14 after CFA injection, a single administration of EL-17 significantly reduced CFA-dependent hypersensitivity to mechanical noxious stimuli and the postural unbalance related to spontaneous pain. To evaluate the preventive efficacy, EL-17 was administered daily starting from the day of CFA treatment. Behavioural measurements performed on days 7 and 14 showed a progressive efficacy of EL-17 against hypersensitivity to mechanical noxious and non-noxious stimuli, as well as a decrease of hind limb weight-bearing alterations. Histological evaluation of the tibiotarsal joint (day 14) demonstrated significant prevention of articular derangement after EL-17 (30 mg/kg) treatment. The protective effects of EL-17 directly correlated with a complete reversion of the plasma NE activity increase induced by CFA. CONCLUSIONS: The NE inhibitor EL-17 relieved articular pain after acute administration. Furthermore, repeated treatment reduced the development of hypersensitivity and protected joint tissue, revealing a disease-modifying profile.

Joint-Sparing Corrections of Malunited Chopart Joint Injuries.

Treatment of malunion and nonunion at the Chopart joint aims at axial realignment of the midfoot to the hindfoot and restoration of the normal relationship of the lateral and medial columns of the foot. In carefully selected patients with intact cartilage, joint-preserving osteotomies are feasible at all 4 bony components of the Chopart joint to restore near-normal function. Priority should be given to the anatomic reconstruction of the talonavicular joint because it is essential for global foot function. Patients must be counseled about the risk of progressive arthritis or osteonecrosis necessitating late fusion.

Diagnosis and Surgical Management of Congenital Laxity of the Fibularis Musculotendinous Unit Resulting in Hyperextension of the Tarsus in 14 Calves.

OBJECTIVE: To describe the diagnosis and surgical management of congenital laxity of the fibularis tendon resulting in hyperextension of the tarsus in calves. STUDY DESIGN: Case series. ANIMALS: Fourteen calves (3 unilateral, 11 bilateral) diagnosed with congenital tarsal instability caused by laxity of the fibularis musculotendinous unit resulting in hyperextension of the tarsus. METHODS: Diagnosis was made by clinical and radiologic assessments. The tarsus was surgically prepared and an incision made on the dorsal surface of the tarsus after intrathecal anesthesia with the calf sedated. A locking-loop suture (4 loops) was applied to the fibularis tendon using polyglactin 910. The free ends of the suture were then tied to the shank of a cortical bone screw inserted in the proximal metatarsus. RESULTS: The calves were evaluated on postoperative days 15, 30, and 60 and were walking normally. CONCLUSION: Congenital tarsal instability because of laxity of the fibularis musculotendoninous unit is described and surgical treatment directed at shortening the tendon shows promising results.

Clinical diagnosis of symptomatic midfoot osteoarthritis: cross-sectional findings from the Clinical Assessment Study of the Foot.

OBJECTIVE: To derive a multivariable diagnostic model for symptomatic midfoot osteoarthritis (OA). METHODS: Information on potential risk factors and clinical manifestations of symptomatic midfoot OA was collected using a health survey and standardised clinical examination of a population-based sample of 274 adults aged ≥50 years with midfoot pain. Following univariable analysis, random intercept multi-level logistic regression modelling that accounted for clustered data was used to identify the presence of midfoot OA independently scored on plain radiographs (dorso-plantar and lateral views), and defined as a score of ≥2 for osteophytes or joint space narrowing in at least one of four joints (first and second cuneometatarsal, navicular-first cuneiform and talonavicular joints). Model performance was summarised using the calibration slope and area under the curve (AUC). Internal validation and sensitivity analyses explored model over-fitting and certain assumptions. RESULTS: Compared to persons with midfoot pain only, symptomatic midfoot OA was associated with measures of static foot posture and range-of-motion at subtalar and ankle joints. Arch Index was the only retained clinical variable in a model containing age, gender and body mass index. The final model was poorly calibrated (calibration slope, 0.64, 95% CI: 0.39, 0.89) and discrimination was fair-to-poor (AUC, 0.64, 95% CI: 0.58, 0.70). Final model sensitivity and specificity were 29.9% (95% CI: 22.7, 38.0) and 87.5% (95% CI: 82.9, 91.3), respectively. Bootstrapping revealed the model to be over-optimistic and performance was not improved using continuous predictors. CONCLUSIONS: Brief clinical assessments provided only marginal information for identifying the presence of radiographic midfoot OA among community-dwelling persons with midfoot pain.

Neutral heel lateral push test: The first clinical examination of spring ligament integrity.

INTRODUCTION: The spring (calcaneonavicular) ligament is an intricate multiligament complex whose primary role is to stabilise the medial longitudinal arch and head of talus. Clinical suspicion of a spring ligament injury in isolation is roused when persistent medial midfoot pain is present with associated pes planus following trauma. METHOD: We undertook a cadaveric study on 21 specimens to assess the use of a neutral heel lateral push test to examine the spring ligament in a standardised procedure, measuring lateral translation with graduated antegrade and retrograde defunctioning of surrounding structures and the spring ligament. RESULTS: In all specimens, a significant displacement occurred on incision of the spring ligament regardless of order of dissection. The degree of displacement increased by an insignificant amount as surrounding structures were incised at each incremental force applied. DISCUSSION: The neutral heel push test is the first clinical examination to be described to determine integrity of the spring ligament complex. Our study objectively demonstrates that lateral displacement in relation to the mid and hind-foot is influenced most significantly by the integrity of the spring ligament and to a lesser extent by tibialis posterior and flexor digitorum longus.

Contribution of the medial malleolus to tibiotalar joint contact characteristics.

BACKGROUND: Isolated medial malleolus fractures are typically treated operatively to minimize the potential for articular incongruity, instability, nonunion, and posttraumatic arthritis. The literature, however, has not clearly demonstrated inferior outcomes with conservative treatment of these injuries. This study measured the effects of medial malleolus fracture and its resultant instability on tibiotalar joint contact characteristics. We hypothesized that restoration of anatomical alignment and stability through fixation would significantly improve contact characteristics. METHODS: A Tekscan pressure sensor was inserted and centered over the talar dome in 8 cadaveric foot and ankle specimens. Each specimen was loaded at 700 N in multiple coronal and sagittal plane orientations. After testing fractured samples, the medial malleolus was anatomically fixed before repeat testing. Contact area and pressure were analyzed using a 2-way repeated-measure ANOVA. RESULTS: In treated fractures, contact areas were higher, and mean contact pressures were lower for all positions. These differences were statistically significant in the majority of orientations and approached statistical significance in pure plantarflexion and pure inversion. Decreases in contact area varied from 15.1% to 42.1%, with the most dramatic reductions in positions of hindfoot eversion. CONCLUSIONS: These data emphasize the importance of the medial malleolus in maintaining normal tibiotalar contact area and pressure. The average decrease in contact area after simulated medial malleolar fractures was 27.8% (>40% in positions of hindfoot eversion). Such differences become clinically relevant in cases of medial malleolar nonunion or malunion. Therefore, we recommend anatomical reduction and fixation of medial malleolus fractures with any displacement. LEVEL OF EVIDENCE: Therapeutic Level V-Cadaveric Study.