Wayne S. Berberian

Use of bone morphogenetic protein-2 in the rabbit ulnar nonunion model.

The ability of the osteoinductive protein and recombinant human bone morphogenetic protein-2, combined with polylactic glycolic acid porous microspheres and autologous blood clot to heal a large segmental defect was tested in a rabbit diaphyseal defect model. Two centimeter nonuniting defects were surgically created in the bilateral ulnae of 50 male New Zealand white rabbits. Each defect was then implanted with a pastelike polylactic glycolic acid/blood clot combination that was mixed with 5 different concentrations of recombinant human bone morphogenetic protein-2. The forearms were radiographically assessed on a biweekly schedule for 8 weeks. At 8 weeks, all animals were sacrificed and forearms radiographed. Radiographs were then scored by 3 independent observers for bone formation and union rates. United limbs were tested in torsion for mechanical strength using a Burstein torsion tester. All nonunited limbs were analyzed histologically as were 2 united limbs from each dosage group. Radiographic evaluation revealed that there was a dose dependent response in healing of the ulnar defect with a higher bone formation rate in the 2 higher dose limbs than in the lower dose limbs. Union was achieved in 100% of the highest dose limbs, whereas only 50% of the lowest dose limbs achieved bony union. No defects implanted with carrier alone achieved union. Biomechanical studies revealed significantly stiffer bone than age matched controls. Histologic analysis demonstrated normal bone formation with abundant normal appearing osteoid. These dose response data further support the role of recombinant human bone morphogenetic protein-2 as a potent morphogen in bone regeneration.

Nonoperative treatment of adult acquired flat foot with the Arizona brace

Nonoperative treatment of posterior tibial tendon dysfunction can be successful with the Arizona AFO brace, particularly when treatment is initiated in the early stages of the disease. This mandates that the orthopedist has a high index of suspicion when evaluating patients to make an accurate diagnosis. Although there is a role for surgical management of acquired flat feet, a well-fitted, custom-molded leather and polypropylene orthosis can be effective at relieving symptoms and either obviating or delaying any surgical intervention. In todays climate of patient satisfaction directed health care, a less invasive treatment modality that relieves pain may prove to be more valuable than similar pain relief that is obtained after surgery. Questions regarding the long-term results of bracing remain unanswered. Future studies are needed to determine if disease progression and arthrosis occur despite symptomatic relief with a brace. Furthermore, age- and disease stage-matched control groups who are randomized to undergo surgery or bracing are necessary to compare these different treatment modalities. At this time, the Arizona AFO brace can be a useful weapon in the orthopedists armamentarium for treating acquired flat foot deformity.

Prospective, randomized, multi-center feasibility trial of rhPDGF-BB versus autologous bone graft in a foot and ankle fusion model.

Background: The increased morbidity and surgical time associated with harvesting autologous bone graft (ABG) have encouraged surgeons to develop synthetic orthobiologic alternatives. The recombinant form of platelet-derived growth factor (rhPDGF-BB), an angiogenic, mitogenic, and chemotactic cytokine, has been shown to significantly enhance bone formation in human periodontal osseous defects when combined with a tricalcium phosphate carrier (β-TCP). The purpose of this prospective, controlled, randomized, multi-center feasibility clinical trial was to compare the safety and efficacy of this biosynthetic bone graft substitute (Augment™ Bone Graft) to ABG during ankle and hindfoot fusion. Materials and Methods: Twenty adult subjects requiring ankle or hindfoot fusion from three U.S. centers were enrolled and randomized in a 2:1 ratio to receive Augment™ or ABG, respectively. Surgical approach and fixation techniques were standardized, and minimum followup was 9 months. The primary endpoint was radiographic osseous union, evaluated by a blinded independent radiologist. Secondary endpoints included assessment of clinical success, union rate by serial computed tomography (CT) examination, time to full weightbearing, AOFAS Ankle-Hindfoot Score (AOFAS), Foot Function Index (FFI), Short Form-12 (SF-12), and Visual Analog pain assessment Scale (Pain VAS). Results: At 36 weeks, 77% (10/13) of the Augment™ and 50% (3/6) of the ABG patients were fused based on radiographic criteria. There were two nonunions in the Augment™ group (9%, 2/14). Healing rates based on 12 week CT scanning (50% osseous bridging) were 69% (9/13) in the Augment™ and 60% (3/5) in the ABG groups, respectively. All functional outcome measures (FFI, AOFAS, SF-12), as well as the VAS pain scores, improved in both groups over time. Surgical procedure times lasted an average 26 minutes longer for the ABG as compared to the Augment™ populations. There were no device related serious adverse events in this study. Conclusion: Based on the available data, the rate of radiographic union, time to full weightbearing, and outcomes scores between the Augment™ and ABG subjects appear comparable. Augment™ may represent a safe and efficacious treatment alternative to ABG during foot and ankle arthrodesis. Level of Evidence:

Missed and Associated Injuries after Subtalar Dislocation: The Role of CT

Subtalar joint dislocation (STJD) is an uncommon injury, but carries with it a potential for significant functional disability. We hypothesized that a significant number of injuries associated with subtalar joint dislocation may be unrecognized by plain radiographic examination. Therefore, we reviewed the records of all STJDs over a three-year period, identifying nine cases. The majority of injuries occurred in men (78%) with a mean age of 29 years. Overall, the mean age at injury was 32 years. The right lower extremity was most frequently injured (87.5%). Plain films initially diagnosed a STJ dislocation in all patients. A CT scan was performed in ail cases. In 100% of patients, CT identified additional injuries missed on initial plain radiographs. In 44% of patient, new information gathered by CT dictated a change in treatment. Based on our findings, we conclude that CT is an invaluable tool to assess for associated injuries in STJ dislocation, and should be performed in all cases of STJ dislocation.

Pseudo os trigonum sign: missed posteromedial talar facet fracture.

Background: Posteromedial talar facet fracture (PMTFF) is a rare injury, sparsely reported in the literature. This article proposes that PMTFF is often left undiagnosed by orthopaedic surgeons and suggests the routine application of advanced radiographic studies (i.e., CT scan) in the recognition of PMTFF. It also evaluates nonoperative management of PMTFF. Methods: After obtaining Institutional Review Board approval, the medical records over a 5-year period (1997–2001) were retrospectively reviewed from the foot and ankle service of a level 1 trauma center, identifying all cases of PMTFF. Charts were reviewed for relevant data. Results of treatment were assessed during follow-up physical examination. Results: Six cases of PMTFF were identified over a 5-year period. All injuries were associated with medial subtalar joint dislocation. Four of six (66%) patients were not initially diagnosed with PMTFF, but instead misdiagnosed as an os trigonum. The remaining two patients had an established diagnosis of PMTFF at the time of initial treatment. All had short leg cast immobilization for medial subtalar dislocation. CT evaluation yielded additional diagnoses in all six patients. All six patients showed a PMTFF. Five patients (83%) revealed persistent subtalar joint subluxation. Five of six (83%) patients required at least one additional procedure as a result of an undiagnosed or nonoperatively treated PMTFF. Four patients underwent subtalar joint fusion, and one patient underwent tibiotalar calcaneal fusion secondary to concomitant ankle/subtalar arthritis. The patient who did not undergo recommended fusion continued to be symptomatic. Conclusions: Diagnosis of PMTFF necessitates a heightened clinical suspicion, especially when a medial subtalar joint dislocation is present. Proper imaging studies, such as coronal CT scan, should be performed after any subtalar dislocation. Timely treatment, in the form of open reduction and internal fixation for large fragments involving the articular surface or surgical excision for smaller fragments, is recommended in order to restore proper anatomy and function of the subtalar joint. This study verifies the significant morbidity associated with an undiagnosed or nonoperatively treated PMTFF.

Fatigue testing of cerclage stainless steel wire fixation

Summary: Because wire fixation continues to be used extensively in the practice of orthopaedic surgery, despite a high incidence of wire breakage, understanding the mechanism of this failure is of important clinical interest. The aim of this study was to investigate the failure of cerclage stainless steel wire using an in vitro cyclic loading device. A stainless steel testing fixture consisting of two half cylinders with a combined diameter of 2.5 cm was mounted in a servo hydraulic testing machine. Specimens of number 18 gauge (0.97 mm diameter) and number 16 gauge (1.22 mm diameter) 316L stainless steel wire were mounted around the two half cylinders in a cerclage manner using three different fastening methods: a uniform symmetrical twist, a knot twist, and a square knot. Single-load-to-failure and cyclic load tests were performed under controlled tensile displacement. The cerclage wire system fastened with a twist resulted in failure at loads significantly lower than systems fastened with the knot twist and the square knot. Cyclic loading of the wire fastened with twists also showed decreased fatigue properties when compared to those fastened with the knot twist and the square knot. In all tests, the 16-gauge wire was found to be clearly superior to the 18-gauge wire. For both wires, fatigue strengths at 100,000 cycles were only 30-37% of the static ultimate strength. These results show that wire diameter and fastening system are two important factors affecting the mechanical properties of the resulting fixation.

A biomechanical evaluation of the long stem intramedullary hip screw.

Summary: Despite the advantages associated with short-stem intramedullary hip screw devices for the treatment of intertrochanteric fractures, recent reports have shown an increased incidence of femoral shaft fractures after their insertion. These findings led to the hypothesis that an intramedullary hip screw with a longer stem may more effectively redistribute loads to the distal end of the femoral shaft, where they may be more readily absorbed by the increased bony cross-sectional area. To characterize the load patterns of a long-stem device in the femur, 10 fresh-frozen adult femurs were instrumented with unidirectional strain gauges. A total of eight strain gauges were placed in the direction of principal femoral strains on the medial and lateral surfaces of each femur. Each femur was held in a steel vice at 15° of adduction in the coronal plane and vertical in the sagittal plane. The femurs were then subjected to successively increasing vertically applied compressive loads from 0 N to 1,400 N at 200-N increments using a servohydraulic testing machine. Strain values were recorded at each load after a 5-min equilibration period. Each femur was tested under five conditions: (a) intact, (b) after insertion of the long-stem intramedullary hip screw device, (c) with an experimentally created two-part fracture, (d) with a stable four-part fracture, and (e) with an unstable four-part fracture with the posteromedial fragment removed. Half the femurs were randomly assigned to have two distal interlocking screws placed before fracture. The remaining half were loaded without distal interlocking screws. The results indicate that the loads on the femur with intertrochanteric fractures are redistributed such that the proximal femur is subjected to significantly lower strains. Moreover, even though strain values in the distal metaphysis at the site of load transfer were relatively high, they did not differ significantly from the values recorded in the intact femur. Thus, the long-stem intramedullary hip screw device transmits progressively decreasing load to the proximal femur with increasing fracture instability and redistributes this load throughout the distal femur without significantly increasing distal femoral strain values

Orthotic devices. Degenerative disorders of the foot and ankle.

Orthotic devices are an effective method of treating degenerative arthrosis of the foot and ankle. When combined with appropriate medications and activity modifications, operative intervention may be postponed or rendered unnecessary. A thorough comprehension of relevant anatomy, biomechanics, and available devices is crucial to maximize the benefits of this modality.

An Analysis of 2 Fusion Methods for the Treatment of Osteomyelitis Following Fractures About the Ankle

Background: In the setting of chronic osteomyelitis following fractures about the ankle, reconstruction through bony arthrodesis may be used as a reconstructive alternative to amputation. During these cases, surgeons often avoid using internal fixation in an attempt to avoid reinfection or premature hardware failure. In this retrospective review, we analyzed the outcomes of chronic osteomyelitic patients who had an arthrodesis of the ankle using either internal or external fixation, focusing on salvage rates, infection clearance, union rates, and functional outcomes. No device was implanted into a known active infection. Methods: We performed a retrospective chart review of adult patients undergoing arthrodesis in the setting of a previously septic ankle following a traumatic injury. In each case, multiple irrigation and debridement procedures and local and systemic antibiotics were used. Infection status was determined by clinical exam, MRI, nuclear medicine studies, and ultimately bone biopsies. No fixation device was implanted in ankles with known active infections. Patients were divided into 2 cohorts: those fused with internal devices and those fused with external fixators. Thirty patients underwent a total of 32 arthrodesis procedures. Mean follow up time was 27 months (range, 6 to 144). Results: Nineteen fusions were performed using internal fixation; only 2 required amputations, therefore limb salvage was 90%. Fifteen were able to ambulate with or without the assistance of an orthosis (79%). Four patients experienced recurrent infection (21%) and 5 developed nonunion (26%). Of the 13 fusions performed with external fixators, only 1 required an amputation, putting limb salvage at 92%. Ten patients were able to walk with or without the assistance of an orthosis as their final functional status (77%). Two patients experienced recurrent infection (15%), and 4 went on to nonunion (31%). Conclusion: When analyzing these 2 fusion methods in posttraumatic patients with previously septic ankles, with the numbers available both methods achieved similar rates of limb salvage and final functional status in these patients, as well as similar rates of infection clearance and bony union. As internal fixation is often less labor-intensive for the surgeon and more palatable for the patient postoperatively, we encourage surgeons to consider arthrodesis with internal fixation once the infection is successfully eradicated, especially in a noncompliant patient population. Level of Evidence: Level III, retrospective comparative series.

Calcanectomy for Treatment of the Infected Os Calcis

Osteomyelitis of the os calcis presents a difficult challenge to the treating physician. Because the condition often occurs in the setting of concurrent medical comorbidities, such as diabetes mellitus (DM), in adults, conservative treatment options are generally unsuccessful in eradicating the infection and preserving function of the extremity. However, limb-sparing surgery that effects cure of the infection is preferable because of the morbidity associated with amputation. The article presents a historical perspective on the various treatment options of the infected os calcis, the indications and contraindications for calcanectomy, and a description of the operative technique for calcanectomy. Complications and postoperative management, as well as the authors’ patient series results, are also presented.