Faculty Bibliography

BACKGROUND: Treatment of tibial stress fractures in elite dancers is centered on rest and activity modification. Surgical intervention in refractory cases has important implications affecting the dancers' careers. HYPOTHESIS: Refractory tibial stress fractures in dancers can be treated successfully with drilling and bone grafting or intramedullary nailing. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between 1992 and 2006, 1757 dancers were evaluated at a dance medicine clinic; 24 dancers (1.4%) had 31 tibial stress fractures. Of that subset, 7 (29.2%) elite dancers with 8 tibial stress fractures were treated operatively with either intramedullary nailing or drilling and bone grafting. Six of the patients were followed up closely until they were able to return to dance. One patient was available only for follow-up phone interview. Data concerning their preoperative treatment regimens, operative procedures, clinical union, radiographic union, and time until return to dance were recorded and analyzed. RESULTS: The mean age of the surgical patients at the time of stress fracture was 22.6 years. The mean duration of preoperative symptoms before surgical intervention was 25.8 months. Four of the dancers were male and 3 were female. All had failed nonoperative treatment regimens. Five patients (5 tibias) underwent drilling and bone grafting of the lesion, and 2 patients (3 tibias) with completed fractures or multiple refractory stress fractures underwent intramedullary nailing. Clinical union was achieved at a mean of 6 weeks and radiographic union at 5.1 months. Return to full dance activity was at an average of 6.5 months postoperatively. CONCLUSION: Surgical intervention for tibial stress fractures in dancers who have not responded to nonoperative management allowed for resolution of symptoms and return to dancing with minimal morbidity

BACKGROUND: Although anterior cruciate ligament (ACL) sprains usually occur during the initial phase of the landing cycle (less than 40 degrees knee flexion), the literature has focused on peak values of knee angles, vertical ground reaction force (VGRF), and muscle activity even though it is unclear what occurs during the initial phase of landing. OBJECTIVES: The objectives of this study were to determine the effects of sex (male and female) and fatigue (prefatigue/post-fatigue) on knee flexion angles at the occurrence of peak values of biomechanical variables [knee valgus angle, VGRF, and normalized electromyographic amplitude (NEMG) of the quadriceps and hamstring muscles] during a bilateral drop landing task. METHODS: Knee valgus angle, VGRF, and NEMG of the quadricep and hamstring muscles were collected during bilateral drop landings for twenty-nine recreational athletes before and after a fatigue protocol. RESULTS: Peak values of knee valgus, VGRF, and NEMG of medial and lateral hamstring muscles occurred during the late phase of the landing cycle (>40 degrees of knee flexion). Females in the post-fatigue condition exhibited peak VGRF at significantly less knee flexion than in the pre-fatigue condition. Males in the post-fatigue condition exhibited peak lateral hamstring muscles NEMG at significantly higher knee flexion than in the pre-fatigue condition. DISCUSSION AND CONCLUSION: Peak values of biomechanical variables that have been previously linked to ACL injury did not occur during the initial phase of landing when ACL injuries occur. No biomechanical variables peaked during the initial phase of landing; therefore, peak values may not be an optimal indicator of the biomechanical factors leading to ACL injury during landing tasks.

BACKGROUND: Ballet and modern dance are jump-intensive activities, but little is known about the incidence of anterior cruciate ligament (ACL) injuries among dancers. HYPOTHESIS: Rigorous jump and balance training has been shown in some prospective studies to significantly reduce ACL injury rates among athletes. Dancers advance to the professional level only after having achieved virtuosic jump and balance technique. Therefore, dancers on the elite level may be at relatively low risk for ACL injury. STUDY DESIGN: Descriptive epidemiology study. METHODS: Dance exposure, injuries, and injury conditions were systematically recorded at 4 dance organizations over 5 years. Select neuromuscular and psychometric variables were compared between and within ACL-injured and noninjured dancers. RESULTS: Of 298 dancers, 12 experienced an ACL injury over the 5-year period. The incidence of ACL injury was 0.009 per 1000 exposures. Landing from a jump onto 1 leg was the mechanism of injury in 92% of cases. Incidence was not statistically different between gender or dance groups, although women modern dancers had a 3 to 5 times greater relative risk than women ballet dancers and men dancers. No difference between ACL-injured and noninjured dancers emerged with regard to race, oral contraceptive use, or select musculoskeletal measures. CONCLUSION: Dancers suffer considerably fewer ACL injuries than athletes participating in team ball sports. The training dancers undertake to perfect lower extremity alignment, jump, and balance skills may serve to protect them against ACL injury. Anterior cruciate ligament injuries happened most often late in the day and season, suggesting an effect of fatigue

STUDY DESIGN: Case report. BACKGROUND: Tendon lacerations of the hallux are potentially devastating to a dancer. Strength of the hallux musculature is necessary to attain and maintain balance, push-off in multiple turns, and decelerate in jumps and hops. The purpose of this paper is to report on the repair and rehabilitation of extensor hallucis longus and extensor hallucis brevis tendon lacerations in a professional dancer. CASE DESCRIPTION: A 30-year-old dancer sustained complete laceration of her extensor hallucis longus and extensor hallucis brevis tendons, and partial laceration of the dorsal aspect of the hallux metatarsophalangeal (MTP) joint capsule. Following primary repair, at 9 weeks postsurgery, hallux MTP joint active dorsiflexion was limited to 5 degrees and passive dorsiflexion to 70 degrees . First toe dorsiflexion and plantar flexion strength was 4/5 at the MTP and 3+/5 at the interphalangeal joint. Rehabilitation included functional electrical stimulation to address considerable calf atrophy, strengthening exercises, functional retraining, and progressive return to dance. OUTCOME: The dancer returned to her previous level of dancing in 18 weeks, with 73 degrees and 85 degrees of hallux MTP joint active and passive dorsiflexion, and 30 degrees and 35 degrees of active and passive plantar flexion, respectively. Hallux MTP and interphalangeal joint muscle strength were 5/5 and 4+/5, respectively. Improvement, manifested in her SF-36 and Dance Functional Outcome System scores, accompanied her full functional recovery. DISCUSSION: Hallux stability provided by coactivation of the great toe extensors and flexors is crucial to accomplish the demands of bipedal and unipedal balances and activities in dance. This report demonstrates the success of primary surgical repair and rehabilitation in a dancer/athlete experiencing this injury

OBJECTIVE: To determine the effect of landing type (unilateral vs. bilateral) and gender on the biomechanics of drop landings in recreational athletes. DESIGN: This study used a repeated measures design to compare bilateral and unilateral landings in male and female athletes. A repeated measures multivariate analysis of variance (type of landing*gender) was performed on select variables. SETTING: Biomechanics laboratory. PARTICIPANTS: Sixteen female and 16 male recreational athletes. MAIN OUTCOME MEASURES: Kinetic, kinematic, and electromyographic (EMG) data were collected on participants while performing bilateral and unilateral landings from a 40-cm platform. RESULTS: Compared to bilateral landings, subjects performed unilateral landings with increased knee valgus, decreased knee flexion at initial contact, decreased peak knee flexion, decreased relative hip adduction, and increased normalized EMG of the rectus femoris, medial hamstrings, lateral hamstrings, and medial gastrocnemius (P < 0.005). During both types of landing, females landed with increased knee valgus and normalized vertical ground reaction force (VGRF) compared to males (P < 0.009), however, the interaction of landing type*gender was not significant (P = 0.29). CONCLUSIONS: Compared to bilateral landings, male and female recreational athletes performed unilateral landings with significant differences in knee kinematic and EMG variables. Female athletes landed with increased knee valgus and VGRF compared to males during both types of landing

BACKGROUND: The purpose of this study was to evaluate the results of arthroscopic treatment of anterior bony and soft-tissue impingement of the ankle in elite dancers. METHODS: The study is a case series retrospectively reviewed. In the period between 1990 and 1999, 11 elite dancers (12 ankles) had ankle arthroscopy after a diagnosis of anterior ankle impingement that markedly interfered with their dancing. Initial nonoperative treatment failed in all subjects. Previous ankle trauma was noted in all subjects. There were seven women and four men (average age 28 years). Tibiotalar exostoses were radiographically noted in six ankles. Standard anteromedial and anterolateral arthroscopic portals and instrumentation were used for resection of bone spurs and debridement of impinging soft tissues. Patients were nonweightbearing for 5 days after surgery and had postoperative physiotherapy. RESULTS: Nine dancers returned to full dance activity at an average of 7 weeks after surgery. One patient did not return to dance performance because of concurrent unrelated orthopaedic problems, but he resumed work as a dance teacher; he developed a recurrent anterior tibial spur that was successfully resected at a second arthroscopy 9 years later. Another dancer developed postoperative scar-tissue impingement and stiffness; she had a repeat arthroscopy 4 months after the initial procedure and subsequently returned to dance performance. All patients eventually had marked postoperative improvement in pain relief and dance performance. CONCLUSIONS: Arthroscopic debridement is an effective method for the treatment of bony and soft-tissue anterior ankle impingement syndrome in dancers and has minimal morbidity

PURPOSE: To review the results of 34 patients who underwent radiofrequency thermal shrinkage (RFTS) for treatment of anterior cruciate ligament (ACL) laxity in the attenuated and partially torn ACL. TYPE OF STUDY: Retrospective cross-sectional survey performed at least 6 months after treatment. METHODS: Patients with recurrent instability after attenuation of ACL autografts and partially torn ACLs were treated with RFTS. Follow-up included subjective questionnaires (International Knee Documentation Committee [IKDC], Tegner, and Lysholm) and objective clinical tests (IKDC, KT-1000, pivot-shift, Lachman, single-leg hop). RESULTS: Mean follow-up was 21.4 months. Based on IKDC and subjective evaluation, 18 of 20 (90%) partially torn ACLs and 10 of 14 reconstructed ACLs (71%) treated with RTFS were judged to have good or excellent knee function (overall 82%). ACL laxity based on KT-1000 was less successful, with 15 of 20 (75%) partially torn ACLs and 8 of 12 (66%) reconstructed ACLs considered successful. CONCLUSIONS: With no major complications in this study, we conclude that RFTS for treatment of ACL laxity is a well-tolerated procedure with success rates around 71% to 90% in selected patients. RFTS may be offered as a less-extensive alternative to patients being considered for ACL reconstruction who have either attenuated or partially torn ligaments, especially in the athletically low-demand population. LEVEL OF EVIDENCE: Level IV, case series