Mark Sobel

The results of treatment of supracondylar fracture above total knee arthroplasty

This study analyzes the results of treatment of 22 patients with 24 supracondylar femur fractures above a total knee arthroplasty. Ten knees were treated by closed methods utilizing traction and then a cast, 10 knees with immediate open reduction and internal fixation, 2 knees with a custom total knee integrated with a distal femoral allograft, 1 knee with external fixation, and 1 knee with primary arthrodesis. Nine fractures treated by closed means and 5 fractures treated by open reduction and internal fixation healed primarily. Two of the 5 surgical failures healed after replating and bone graft. The 3 failures of surgical therapy were salvaged utilizing custom total knee arthroplasty, 2 of which required integration with a distal femoral allograft. One knee treated with external fixation developed a deep infection necessitating implant removal and arthrodesis. Twelve of the 14 femoral fractures that united primarily healed with the femoral component in varus with respect to the long axis of the anatomic femur. Nine of these 12 implants developed progressive radiolucent lines at the tibial component. Three of these knees have required implant revision due to progressive loosening of the tibial and/or femoral components. The results of this evaluation indicate that fractures above a well-fixed total knee arthroplasty are difficult to manage. If anatomical alignment cannot be achieved by simple closed techniques, then primary open reduction and internal fixation should be considered. However, because of the complexity of the problem, the surgeon should be prepared to perform a primary arthrodesis or revision using custom components with or without a distal femoral allograft.

The dynamics of peroneus brevis tendon splits: A proposed mechanism, technique of diagnosis, and classification of injury

The etiology of peroneus brevis splits is unclear. 16,26 Because longitudinal splits in the peroneus brevis tendon do not necessarily effect the integrity or strength of the tendon, it is difficult to ascertain whether or not injury to the peroneus brevis tendon is present. Recent clinical, anatomic, and histologic reports have suggested that the split develops from prolonged mechanical attrition within the fibular groove as a result of ankle trauma with resultant lateral ankle instability and incompetency of the superior peroneal retinaculum with resultant subluxation of the peroneal tendons. 15,17,22 –25 This cascade of events may result in splitting of the peroneus brevis tendon. The purpose of this paper was to report the investigation of the mechanism by which peroneus brevis splits develop, to describe a technique of diagnosis, and to propose a classification of injury. Peroneus brevis splits are the result of a dynamic mechanical insult at the fibular groove. Laxity of the superior peroneal retinaculum combined with peroneus longus mechanical compression causes the peroneus brevis to splay out and eventually split over the sharp posterior edge of the fibula. Anatomic factors, such as a shallow fibular groove (congenital convex groove) or the presence of an anomalous low-lying peroneus brevis muscle belly or peroneus quartus tendon, 4,7,25 may also play a role in this mechanism by interfering with the competence of the superior peroneal retinaculum.

Congenital Variations of the Peroneus Quartus Muscle: An Anatomic Study

There has been little research concerning this muscle since the 1920s, when Hecker 13,14 described this muscle to be present in (13%) of his dissections of cadaver legs. The purpose of our dissections was to establish the incidence of the peroneus quartus muscle, its origins, and insertions. One hundred and twenty-four legs from 65 fresh human cadavers were dissected under loupe magnification. When the peroneus quartus tendon was found, its origin, insertion, and anatomic relationship to the peroneus longus and peroneus brevis were observed. All specimens were sketched and photographed. The peroneus quartus muscle was present in 27 legs (21.7% of specimens). Its origins, insertions, and size varied. In 17 legs (63%) the muscle originated from the muscular portion of the peroneus brevis, and inserted on the peroneal tubercle of the calcaneus. The peroneal tubercle was hypertrophied at the insertion in most cases. The results of this study in general show that there was much higher incidence of the peroneus quartus muscle than Hecker claimed. Its course, origin, and insertion varied. Its tendon can be used for reconstructive procedures about the lateral aspect of the ankle, especially in anterior dislocation of the peroneal tendons and reconstruction of lateral ligaments.

The Stability of Fixation of First Metatarsal Osteotomies

Five different types of osteotomies for the correction of the hallux valgus deformity were performed on dried human first metatarsal bones. These included the step-cut Mitchell osteotomy, a distal transverse osteotomy, a distal biplanar osteotomy, the Chevron osteotomy, and a basilar osteotomy. Each type of procedure was then fixed using a variety of clinically appropriate techniques including single K-wires, crossed K-wires, a single A-0 cancellous screw, a single A-0 cortical screw, and three different types of sutures. Specimens were placed in a test jig and physiological loads applied with a Materials Testing Systems servohydraulic testing machine (Minneapolis, Minnesota). No difference in stability was observed between the various types of osteotomies, except for the Chevron osteotomy, which did possess greater inherent stability. Fixation by screws or multiple K-wires provided the most stable configuration when compared to other methods. The postoperative regimen following first metatarsal osteotomy should take into account the relative stability of fixation. Cast immobilization and a nonweight-bearing status may be preferable after procedures characterized by less mechanical stability.

Longitudinal attrition of the peroneus brevis tendon in the fibular groove: an anatomic study.

There has been little research concerning the attrition of the peroneus brevis tendon since Meyers observation in 1924. The purpose of our dissections was to establish the incidence of the attrition of the peroneus brevis tendon at the fibular groove, and observe the anatomical relationship of the tendon attrition to the bony anatomy of the distal fibula. One hundred and twenty-four fresh human cadavers ankles from 65 cadavers were dissected under loupe magnification. When attrition of the peroneus brevis was found, the extent of attrition was measured, and anatomic proximity of the tendon to distal fibular groove was observed. Evidence of other tendon attrition as well as the depth of the fibular groove was observed. Specimens which revealed attrition of the peroneus brevis were sketched and photographed. Attrition of the peroneus brevis tendon was found in 14 ankles (11.3% of specimens). The attrition was limited only to the peroneus brevis tendon, and in no specimens was the peroneus longus involved. The degree of tendon attrition varied from simple splaying out of the peroneus brevis in the fibular groove to longitudinal splits in the peroneus brevis tendon with significant fraying of the remaining halves of the tendon. The longitudinal ruptures in the peroneus brevis tendon averaged 1.9 cm (range 1–4 cm). In all cases, the central portion of the longitudinal split was centered over the distal tip of the fibula in the fibular groove. In no case was a complete rupture of the peroneus brevis tendon noted. There was gross evidence of chronic inflammation and synovitis in those ankles with attrition of the peroneus brevis tendon. The results of this study in general present a description of the incidence of peroneus brevis attrition, and when present, the variable degree of attrition, the anatomic relationship of the tendon attrition to the fibular groove, and the evidence of synovitis and chronic inflammation associated with tendon attrition. This incidence of occurrence has not been documented before. The significance of this finding is that chronic ankle pain disability may be related to attrition of the peroneus brevis tendon in the fibular groove.

Longitudinal Splitting of the Peroneus Brevis Tendon: An Anatomic and Histologic Study of Cadaveric Material

Gross and microscopic examinations of 21 split and 10 intact cadaveric peroneus brevis tendons were performed in an effort to determine the pathogenesis of longitudinal splitting of this tendon. The split regions were centered over the posterior margin of the distal fibula and were characterized by splaying of the collagen bundles with accompanying proliferation of blood vessels and fibrovascular connective tissue. Inflammatory infiltrates were not present. Regions of the tendons that were not altered had normal cellularity and orientation of the collagen. The findings of this study suggest that the splitting of the tendon develops through a mechanical mechanism.

Giant cell tumor of the distal radius

We compared the outcome of patients with giant cell tumor of the distal radius treated by curettage/cryosurgery and en bloc resection, evaluating oncologic success, functional results, and complications. Thirty consecutive cases of giant cell tumor of the distal radius were treated at our institution between 1958 and 1988. Twenty-six patients were available for follow-up examination, with a minimum follow-up period of 3 years and median follow-up period of 9 years. Primary curettage/cryosurgery had a local recurrence in 3 of 12, and repeat curettage/cryosurgery achieved local control in in 16 of 18 primary and recurrent cases. The major complications in this group included skin necrosis, transient nerve palsies, and fragmentation with carpal collapse. An average of 60% of contralateral range of wrist motion was preserved. Ten patients underwent en bloc excision and arthrodesis for either primary or recurrent tumor; none developed local recurrence. The main complication in this group was failure of internal fixation and non-union at the graft-radius junction. Resultant strength and function were similar in both groups. Intralesional excision with adjunctive cryosurgery is an effective alternative to en bloc excision with the advantage of preserving the distal radius and wrist joint function, but with a notable complication rate. En bloc excision with arthrodesis is more suitable for extensive local disease with poor residual bone stock and as salvage for failed intralesional excision.

Lateral Ankle Instability as a Cause of Superior Peroneal Retinacular Laxity: An Anatomic and Biomechanical Study of Cadaveric Feet

The role of the competent superior peroneal retinaculum (SPR) as a primary restraint to peroneal tendon subluxation and mechanical attritional wear is clear. Injury to the SPR has classically been described as a dorsiflexion aversion movement of the ankle coupled with a forceful peroneal tendon reflex contraction. This mechanism, however, does not cause injury to the lateral collateral ligaments of the ankle and does not explain the coexistent findings of lateral ankle instability, laxity of the SPR, and concurrent peroneal tendon pathology. Anatomic studies reveal a parallel alignment of the calcaneal band of the SPR and the calcaneofibular ligament. A cadaveric model of ankle instability created by serial sectioning of the lateral collateral ligaments revealed increasing visual strain on the SPR with increasing degrees of ankle instability. These findings suggest the SPR serves as a secondary restraint to ankle inversion stress and that the force or forces that result in chronic ankle instability can also injure and attenuate the superior peroneal retinaculum.

Total knee arthroplasty for the treatment of chronic hemophilic arthropathy

Total knee arthroplasty (TKA) for hemophilic (factor VIII deficiency) arthropathy is a complex and demanding procedure with a high complication rate. However, the long-term benefits have not previously been reported. This study reviews 19 TKAs performed for hemophilic arthropathy that were followed for a minimum of 5.5 years and an average of 9.5 years. At present, 13 knees have good or excellent results, and six knees rate as poor or failures. Those patients with excellent results have maintained good pain relief and function. Four of the six failures were among the first seven arthroplasties performed, when only 80% factor VIII coverage was used during the perioperative period. Since the use of 100% factor VIII coverage was instituted, the failure rate has declined. Ten of the 19 knees suffered complications, including one deep infection, six superficial skin necroses, three nerve palsies, seven postoperative bleedings, and one transfusion reaction. Six of the seven knees operated on under 80% factor VIII coverage had complications. Once 100% factor VIII coverage was instituted, the only complications included one skin necrosis and three postoperative bleedings. The roentgenographic failure rate has remained high with progressive roentgenographic lucencies in 13 of 19 tibial components, associated with component shift in three knees. While these roentgenographic findings have not necessarily correlated with clinical results, they are disturbing and may portend future failures. However, pain relief and improved function are maintained at longer follow-up times. The best results were obtained under 100% factor VIII coverage using a posterior stabilized prosthesis and patellar resurfacing.

Chronic ankle instability as a cause of peroneal tendon injury.

Chronic lateral ankle pain and instability can be associated with a split in the peroneus brevis tendon. This case reports a peroneus brevis split that was centered over the sharp posterior edge of the fibula and was associated with laxity of the superior peroneal retinaculum, and chronic ankle instability. The mechanism of the split was easily demonstrated during surgery by everting the foot and pulling longitudinally on the peroneus longus tendon. The interrelationship of lateral ankle instability with superior retinacular laxity and resultant peroneus brevis splits can account for posttraumatic lateral ankle pain. Surgical treatment must identify and correct the underlying pathology and should attempt to repair or debride the peroneus brevis tendon, reconstruct the superior peroneal retinaculum, flatten the posterior edge of the fibula by removing the sharp bony prominence, and address any associated lateral ankle instability with either a modified Chrisman-Snook, Anderson, or modified Brostrom-Gould procedure.