Faculty Bibliography

BACKGROUND:The goal of this study was to identify pressure changes throughout the peroneal groove after a groove deepening procedure. We hypothesized that pressures would decrease. METHODS:Twelve fresh-frozen foot and ankle specimens were used. A thin pressure strip containing four sensor pads was secured within the peroneal groove with pads 1 through 4 positioned at the calcaneofibular ligament (CFL) and at the distal, middle, and proximal groove, respectively. The midstance phase of gait was simulated with loads applied to the plantar foot and posterior tibial tendon and to the peroneus longus and brevis tendons. Pressures were recorded with the ankle in neutral, plantarflexion, dorsiflexion, inversion, and eversion. Groove deepening was done by osteotomizing the posterior fibular wall. Pressure readings were then recorded. Average pressures for each of the four sensor pads after the procedure were compared to those obtained before the procedure. RESULTS:The mean pressure overlying the CFL increased at all five ankle positions; however, these changes were not significant. Significant decreases in pressure were noted within the distal and middle groove at all ankle positions after the peroneal groove deepening procedure. Pressure within the proximal groove increased at all but one position, with a significant difference noted in neutral and plantarflexion. CONCLUSION/CONCLUSIONS:Pressures within the middle and distal peroneal groove significantly decreased after a groove deepening procedure. Combining this technique with peroneal tendon debridement may be advantageous for treatment of partial peroneal tendon tears or recalcitrant peroneal tendinitis.

BACKGROUND:With technological advances in ankle arthroplasty, there has been parallel development in the outcome instruments used to assess the results of surgery. The literature recommends the use of valid, reliable, and responsive ankle scores, but the ankle scores commonly used in clinical practice remain undefined. METHODS:An internet survey of members of the American Orthopaedic Foot and Ankle Society (AOFAS) was conducted to determine which three ankle scores they perceived as most commonly used in the literature, which ones they believe are validated, which ones they prefer, and which they use in practice. RESULTS:According to respondents, the three most commonly used scores were the AOFAS Ankle score, the Foot Function Index (FFI), and the Musculoskeletal Outcomes Data Evaluation and Management System (MODEMS). The respondents believed that the AOFAS Ankle score, FFI, and MODEMS were validated. The FFI and MODEMS are validated, but the AOFAS ankle score is not validated. CONCLUSIONS:Most respondents preferred using the AOFAS Ankle score. The use of the empirical AOFAS Ankle score continues among AOFAS members.

By using three-dimensional magnetic resonance image reconstruction, lateral displacement of the flexor hallucis longus tendon and sesamoid bones was made clearly visible in a living patient. This finding supports a biomechanical model related to disturbed muscle balance at the first metatarsophalangeal joint, which could play an important role in the pathogenesis of hallux valgus and metatarsus primus varus.

Despite reports of high nonunion rates for isolated talonavicular fusion, this procedure may be indicated for some patients, including those for whom increased stability of the talonavicular joint in triple arthrodesis is needed. In the biomechanical cadaveric study reported here, we evaluated fixation methods used to provide optimal stability of talonavicular arthrodesis. A physiologic 3-point loading model was used to measure dorsal displacement of the navicular on the talus with 1 or 2 cannulated 4.5-mm screws across the talonavicular joint both with and without one 7.3-mm cannulated screw across the subtalar joint. Statistically significant differences in displacement under cyclic loading to one-half body weight were found. Use of 2 talonavicular screws and no subtalar screw or 1 talonavicular screw plus 1 subtalar screw decreased the motion, as compared with use of 1 talonavicular screw and no subtalar screw.

BACKGROUND:Several different techniques have been used for fixation of first metatarsocuneiform (MTC) joint arthrodesis, a standard treatment for arthritis, instability, and deformity of the MTC joint. Improved plating systems using locking designs are now available, but no studies have yet compared this construct with other methods. We compared load to failure with a locking plate design versus standard crossed-screw fixation. METHODS:Ten matched pairs of fresh frozen cadaver feet were used. The bone density of each pair was measured with DEXA scanning. One foot of each pair was randomly assigned to have a dorsomedial Normed H titanium locking plate (Normed Medizin-Technik Vertriebs-GmbH, D-78501 Tuttlingen, Germany) applied to the first MTC joint. On the other foot of the pair, fixation of the first MTC joint was done with crossed ACE DePuy 4.0 (DePuy/Ace, Warsaw, IN) titanium cannulated screws. The first metatarsal and first cuneiform were then isolated and planted in an epoxy resin. The specimens were loaded to failure in a four-point bending configuration using a MTS Mini Bionix test frame (MTS Systems Corp., Eden Prairie, MN). Failure was defined as displacement of more than 3 mm at the arthrodesis site. The Student t-test was used to determine any observed differences, with significance set at p <or= 0.05. RESULTS:The mean maximal load to failure was 140.08 N (SD +/- 77.1) for screw fixation alone and 58.09 N (SD +/- 11.86) for the H-locking plate. This difference was statistically significant (p = 0.008). The mean stiffness of the construct for screw fixation alone was 83.10 N/mm (SD +/- 49.8) and 19.96 N/mm for the H-locking plate. This difference also was statistically significant (p = 0.004). CONCLUSION/CONCLUSIONS:Screw fixation for first MTC arthrodesis created a stronger and stiffer construct than did the H-locking plate. This was likely due to the mechanical design of the implants. Compression across the MTC joint could be applied with the screws, but the plate relied on a fixed angle design with no compression.

BACKGROUND:Loss of reduction of proximal metatarsal osteotomies may result from poor bone quality, suboptimal fixation, and limitations inherent in the bony geometry of the osteotomy. This study evaluated the mechanical benefit of adding two supplementary Kirschner wires to the crescentic and Ludloff osteotomies. METHODS:Eleven and 10 matched pairs of cadaver foot specimens were used for the Ludloff and the proximal crescentic metatarsal osteotomies, respectively. Each metatarsal head specimen was then loaded to failure using a servohydraulic MTS Mini Bionix test frame (MTS Systems Corp, Eden Prairie, MN), and the failure gap was measured with an extensometer. To account for variable bone quality in the study specimens, the failure loads were normalized with the measured bone mineral density (BMD) values of the metatarsal specimens. A paired Student's t-test analysis was used to compare the failure loads between the specimens with the conventional osteotomies and the osteotomies supplemented with two axial Kirschner wires. RESULTS:The load-to-failure of the Ludloff osteotomy with two screws and with one proximal screw and two Kirschner wires was 858.5 N cm(2)/gm and 692.3 N cm(2)/gm, respectively (p > 0.05). The average load-to-failure of crescentic osteotomy with one screw and two axial Kirschner wires (458.8 N cm(2)/gm) was significantly higher than the strength of crescentic osteotomy fixed with one screw only (367.5 N cm(2)/gm) (p = 0.05). For the Ludloff osteotomy, 16 specimens (72.7%) failed by more than 2 mm of gapping. The crescentic osteotomy failures included 16 2-mm gap failures (80%). The Ludloff osteotomy showed a trend toward increased fixation stability as compared with both crescentic osteotomy constructs. CONCLUSION/CONCLUSIONS:The use of two supplemental axial Kirschner wires offers a simple and effective means to improve the initial mechanical stability of the proximal crescentic osteotomy and can be used in the standard Ludloff osteotomy to replace the second screw when screw purchase is poor without significant loss of fixation strength. The possible advantage of Kirschner wire flexibility in restoring position after gapping of the osteotomy site should be investigated.

This biomechanical investigation compared two fixation techniques for distal fibular fractures. Elderly cadaver lower extremities with simulated fibula fractures underwent fixation either with a plate and intramedullary Kirschner wires (K-wires) with or without the addition of three screws inserted through the four cortices of the fibula and the tibia. The specimens were axially loaded to body weight on a materials testing machine, and the supinated foot was externally rotated to failure. Displacement at the fracture site was monitored with an extensometer. Comparing the augmented technique with the technique without additional screws, mean stiffness was 460 +/- 100 and 320 +/- 200 N-mm/deg, strength at failure was 31 +/- 10 and 19 +/- 7 N-m, strength at 30 degrees external rotation was 15 +/- 5 and 10 +/- 6 N-m, and axial deformation was 0.04 +/- 0.06 mm and 0.10 +/- 0.04 mm, respectively. All differences were statistically significant.

Previous studies have shown that increasing angulation of the Weil osteotomy produces greater plantar translation of the metatarsal head. Modifications have been proposed to reduce plantar translation. However, there is no evidence that the increased plantar translation with a Weil osteotomy is clinically significant or that these modifications are required. Ten lower extremities consisting of five matched pairs were used to evaluate whether different configurations of the Weil osteotomy altered plantar pressure in a dynamic cadaver model. For each pair, an oblique Weil osteotomy with a 5-mm shift was done on one side and a standard (parallel) Weil osteotomy with a 5-mm shift was done on the matched foot. A 4-mm slice resection and a metatarsal head resection then were done sequentially. Plantar pressures were measured with cyclic loading to 700 N at a frequency of 1 Hz with an F-scan in-shoe sensor on the intact specimens and after each intervention. Increased plantar translation of the metatarsal head with a more oblique Weil osteotomy did not significantly increase plantar pressure, and the 4-mm slice resection did not significantly unload the metatarsal head. Only complete metatarsal head resection significantly unloaded the metatarsal head.