Faculty Bibliography

BACKGROUND:Transarticular pin fixation for ankle stabilization has drawbacks, including ankle joint arthrosis. An extraarticular technique could help avoid these problems. We compared stiffness under minimal dorsiflexion loading with transarticular versus extraarticular fixation. METHODS:Cadaveric specimens from ten lower extremity matched pairs were randomized to receive transarticular or extraarticular fixation. For transarticular fixation, axial pins were passed retrograde through the plantar heel, calcaneus, subtalar joint, talar body, and ankle joint. For extraarticular fixation, the first pin was inserted antegrade from the anterior distal tibia to the posterolateral aspect of the calcaneus tuberosity. The second pin was inserted percutaneously antegrade from the distal medial tibial metaphysis to the dorsal navicular, passing anterior to the ankle and dorsal to the talonavicular joint. Each specimen was subjected to 1000 cycles at 5 mm/s to 100 N. After testing, the extraarticular specimens were dissected to establish the distance of the pin from the flexor hallucis longus (FHL) tendon. RESULTS:There was no significant difference in stiffness between the transarticular and the extraarticular group (mean+/-standard error of the mean) (17.93 N/mm+/-1.0 N/mm and 18.61 N/mm+/-1.07 N/mm, respectively). The lateral pin was 4.2+/-1.4 mm (range, 2.5 to 6.0 mm) from the FHL. CONCLUSIONS:Fixation stiffness with extraarticular crossed antegrade pins was not different from that of transarticular fixation and did not disrupt the ankle or the plantar skin. CLINICAL RELEVANCE/CONCLUSIONS:Extraarticular ankle fixation may help avoid the complications found with the joint, cartilage, and plantar skin disruption associated with transarticular fixation.

BACKGROUND:Lag screw fixation commonly is used to treat avulsion fractures of the posterior calcaneal tuberosity, but this method may not offer reliable fixation. This study compared the strength to failure of lag screws compared to lag screw fixation augmented with suture anchors in these fractures. METHODS:The calcanei and Achilles tendons of 12 fresh lower extremity cadaver matched pairs were dissected and removed. An oblique osteotomy was created in the calcaneus, and two 4.0-mm lag screws were placed nearly perpendicular to the plane of the fracture in the dorsal aspect of the calcaneus with 30 degrees of divergence between them. In the contralateral specimen, the same procedure was done, but with two suture anchors placed 1.5 to 2 mm distal to the osteotomy. A zigzag suture technique through the Achilles tendon was used. The specimens were mounted and placed in a load frame for monotonic loading to failure. A paired Student t-test and a Pearson correlation were used to analyze the data (p <or= 0.05). RESULTS:The specimens treated with lag screws alone failed at 251.3 (range 66 to 459) N whereas specimens repaired with lag screws and suture anchors failed at 441.6 (range 274 to 661; p = 0.01 N). CONCLUSIONS:Suture anchor augmentation significantly improved the strength of screw fixation of the calcaneal posterior tuberosity avulsion fractures. CLINICAL RELEVANCE/CONCLUSIONS:The use of suture anchor augmentation as described may improve the reliability of fixation in avulsion fractures of the posterior calcaneal tuberosity.

Efficacy and morbidity of a surgically implanted direct-current bone stimulator were evaluated in 38 patients (40 feet) with fracture nonunion or at high risk for nonunion; 14 of these patients had Charcot (diabetic) neuroarthropathy. Union occurred in 26 (65%) of the 40 feet; complications other than nonunion occurred in 16 feet (40%). Two amputations (5%) were performed in cases of intractable neuritis and deep infection. Of the 6 cases of deep infection (15%), 5 resolved with device removal, and the sixth case required below-knee amputation. Use of a bone stimulator in patients with diabetes may be problematic, but the device did not have any adverse effects in other high-risk patients.

BACKGROUND:This study compared intramedullary (IM) fixation for tibiotalocalcaneal arthrodesis with and without a tibiotalocalcaneal augmentation screw. METHODS:Each specimen in six matched pairs of fresh frozen cadavers underwent tibiotalocalcaneal arthrodesis with an IM nail. One specimen from each pair also received a tibiotalocalcaneal augmentation screw. Initial and final stiffness, load to failure, and construct deformation at failure were calculated with dorsiflexion loading. Bone mineral density of each pair was determined. Statistical analysis was done using a paired Student t-test and a Pearson correlation. RESULTS:Initial and final stiffness and load to failure were significantly higher for the tibiotalocalcaneal screw augmented fixation group as compared with the specimens with no additional screw (initial stiffness, 128.0 versus 78.4 N/mm, p = 0.04; final stiffness, 230.9 versus 164.7 N/mm, p = 0.04; load to failure, 875.5 versus 660.2 N, p = 0.03). There was a significant negative correlation between bone mineral density and average construct deformation in the samples without the added tibiotalocalcaneal screw (r = -0.90, p = 0.02). CONCLUSIONS:In tibiotalocalcaneal arthrodesis with intramedullary nail fixation, a tibiotalocalcaneal augmentation screw provides more stable fixation. CLINICAL RELEVANCE/CONCLUSIONS:Use of an augmentation screw as described in this study may lead to lower complication rates, particularly in patients with osteopenic bone.

The adult acquired flatfoot deformity is characterized by flattening of the medial longitudinal arch with insufficiency of the supporting posteromedial soft tissue structures of the ankle and hindfoot. While the etiology of this deformity can be arthritic or traumatic in nature, it is most commonly associated with posterior tibial tendon dysfunction (PTTD). By one estimate, PTTD affects approximately five million people in the United States. The clinical presentation of adult flatfoot can range from a flexible deformity with normal joint integrity to a rigid, arthritic foot.

Subtalar arthroereisis as an adjunct procedure may hold promise for patients who have mild and more severe variants of posterior tibial tendon dysfunction (PTTD). The biomechanics of the implant function have not been fully elucidated, and questions remain about the best clinical indications for the device. This article reviews the limited existing literature and describes the author's personal experience testing subtalar arthroereisis in the laboratory and using the implant clinically for correction of adult flexible flatfoot.

BACKGROUND:Over the past 20 years, ankle arthrodesis with use of screw augmentation has become a popular technique to gain fusion of the arthritic ankle. The objective of this cadaver study was to identify the risks to local neurovascular structures using standard operative practices for percutaneous guide pin placement. METHODS:Nine fresh frozen cadaver limbs were used. A guide pin from the Synthes (Paoli, PA) 7.3-mm cannulated set was placed percutaneously into the distal posterolateral leg with the ankle held in neutral position. A layered dissection was then performed from the skin to tibia. Neurovascular injury and distance of the guide pin from the sural and tibial nerves were noted. RESULTS:The guide pin did not touch the sural or tibial nerves in any specimens. With this technique, the mean distance of the pin from the sural nerve and tibial nerve at the closest point was 0.9 mm and 6.5 mm, respectively. CONCLUSIONS:In placement of a percutaneous screw, care should be taken to start the posterolateral guide pin placement more lateral or closer to the fibula at this level in the leg to avoid injury to the sural nerve. Additionally, the tibial nerve is potentially an at risk structure if percutaneous pin insertion crosses medial to the coronal plane midline. CLINICAL RELEVANCE/CONCLUSIONS:The use of percutaneous screw placement is safe and effective with minimal risk to local neurovascular structures if standard operative technique is followed.

BACKGROUND:Lateral column lengthening has been associated with residual forefoot supination and symptomatic lateral overload in treatment of acquired flatfoot. A medial column procedure may be useful to redistribute load to the medial column. We evaluated radiographic and pressure changes in a severe flatfoot model with lateral column lengthening and investigated the effect of an added first metatarsocuneiform arthrodesis. METHODS:Ten cadaver specimens were loaded in simulated double-legged stance, and radiographic and pressure data were collected for all tested states. Calcaneocuboid arthrodesis was done with a 10-mm foam wedge. Residual forefoot varus was corrected through the first metatarsocuneiform joint. RESULTS:Differences in the mean lateral talar-first metatarsal angle, talonavicular angle, talocalcaneal angle, and calcaneal pitch were significant between the intact foot and the flatfoot. After calcaneocuboid distraction arthrodesis and tendon transfer, the lateral talar-first metatarsal angle, talonavicular angle, and calcaneal pitch were significantly different from the flatfoot. After added first metatarsocuneiform arthrodesis, the talonavicular angle was not significantly different from the intact foot. Lateral forefoot pressure increased in the flatfoot after lateral column lengthening but was not significantly different from the intact foot after first metarsocuneiform arthrodesis was added. CONCLUSIONS:Adding first metatarsocuneiform arthrodesis to calcaneocuboid distraction arthrodesis for treatment of flatfoot deformity provided improvement in radiographic and pedobarographic parameters of a severe model of stage II posterior tibial tendon dysfunction.

BACKGROUND:The purpose of this study was to identify subtypes of atraumatic osteoarthritis of the tarsometatarsal joints based on accompanying foot deformities and to determine whether concurrent procedures done for each subtype were effective. METHODS:The study included 59 patients (67 feet) with atraumatic tarsometatarsal joint osteoarthritis treated with tarsometatarsal fusion. The average patient age was 60.2 years with 40.6 months followup. Patients were evaluated with radiographs, the American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Scale, the Foot Function Index, and the Short Form-36 Health Survey Questionnaire (SF-36). RESULTS:Four main subtypes were identified based on associated foot deformities: pes planovalgus (27), hallux valgus (11), in-situ without deformities (eight), and rockerbottom (five). Plantar-medial closing-wedge resection was used to correct rockerbottom deformity. For pes planovalgus deformity, a medial sliding calcaneal osteotomy was done. Lateral column lengthening with medial sliding calcaneal osteotomy was done for tarsometatarsal osteoarthritis with severe pes planovalgus, and triple arthrodesis was done for rigid pes planovalgus. Tarsometatarsal osteoarthritis with hallux valgus deformity was corrected with the Lapidus procedure. There were 29 complications, most commonly sesamoid pain. The pes planovalgus group showed significant radiographic improvements in four of five parameters measured. AOFAS scores improved from retrospectively assigned preoperative 34.1 points to postoperative 83.9 points. The Foot Function Index showed a high satisfaction rate (86.6%). SF-36 scores averaged 50.6 postoperatively. CONCLUSIONS:When feet with atraumatic tarsometatarsal osteoarthritis are classified into four main categories based on associated deformities, appropriate concurrent procedures can be done with high satisfaction and improved function scores. Pes planovalgus feet, in particular, may benefit from concurrent procedures with improved radiographic measures.

BACKGROUND:Lengthening of the lateral column is commonly used for reconstruction of the adult and pediatric flatfoot, but can result in supination of the foot and symptomatic lateral column overload. The addition of a medial cuneiform osteotomy has been used to redistribute forces to the medial column. The combined use of a lateral column lengthening and medial cuneiform osteotomy in a reproducible cadaver flatfoot model was evaluated. METHODS:Twelve cadaver specimens were physiologically loaded and each was evaluated radiographically and pedobarographically in the following conditions: 1) intact, 2) severe flatfoot, 3) lateral column lengthening with simulated flexor digitorum longus transfer, and 4) lateral column lengthening and flexor digitorum longus (FDL) transfer with added medial cuneiform osteotomy. The lateral column lengthening was performed with a 10-mm foam bone wedge through the anterior process of the calcaneus, and the medial cuneiform osteotomy was performed with a dorsally placed 6-mm wedge. RESULTS:Lateral column lengthening with simulated FDL transfer on a severe flatfoot model resulted in a significant change as compared with the flatfoot deformity in three measurements: in lateral talus-first metatarsal angle (-17 to -7 degrees; p<0.001), talonavicular angle (46 to 24 degrees; p<0.001), and medial cuneiform height (16 to 20 mm; p<0.001). Lateral forefoot pressure increased from 24.6 to 33.9 kPa (p<0.001) after these corrections as compared with the flatfoot. Adding a medial cuneiform osteotomy decreased the lateral talar-first metatarsal angle from -7 to -4 degrees, decreased the talonavicular coverage angle from 24 to 20 degrees, and increased the medial cuneiform height from 20 to 25 mm. After added medial cuneiform osteotomy, lateral pressure was significantly different from that of the flatfoot (p=0.01) and was not significantly different from that of the intact foot (p=0.14). Medial forefoot pressure was overcorrected as compared with the intact foot with added medial cuneiform osteotomy. CONCLUSIONS:Lateral column lengthening increased lateral forefoot pressures in a severe flatfoot model. An added medial cuneiform osteotomy provided increased deformity correction and decreased pressure under the lateral forefoot.