Faculty Bibliography

We present a case of intraarticular myositis ossificans in the right knee of a child. Myositis ossificans (MO), though relatively rare in childhood and even more uncommon within a joint, should be included in the differential diagnosis of an intra-articular mass when indicated by the typical clinical, radiographic, and histologic findings. An 11-year-old male presented with a history of trauma to his right knee. Four weeks after the initial injury, an MRI demonstrated evidence of an ACL rupture with a 'cystic mass' within the intercondylar notch along the anterior surface of the torn ligament. At subsequent arthroscopy, the mass noted on MRI was removed. The histology was consistent with MO. The authors believe this to be the first case of MO in the intercondylar notch detected by MRI, treated by arthroscopy, and confirmed by histology

The most popular criterion cited in the dance literature for advancement to pointe work is attainment of the chronological age of 12 years. However, dancers at this age vary greatly in terms of musculoskeletal maturity and motor skill development. The purpose of this study was to investigate whether objective, functional tests could be used in conjunction with dance teacher expertise to determine pointe-readiness. It was hypothesized that dynamic tests of motor control can better indicate pointe-readiness than chronological age alone or in combination with static musculoskeletal measurements. Thirty-seven pre-pointe students from two professional ballet schools were tested for muscular strength, ankle joint range of motion, single leg standing balance, dynamic alignment, and turning skill. In addition, the participating students' ballet teachers independently graded each student on her readiness to begin dancing en pointe. Performance on three functional tests (the Airplane test, Saute test, and Topple test) was closely associated with teacher subjective rating for pointe-readiness. It is concluded that these tests may be more useful for gauging acquisition of the skills required for safe and successful performance than the traditionally accepted indicators of chronological age, years of dance training, and ankle joint range of motion.

This article reviews selected issues of importance in the evaluation, treatment, and reconditioning of dancers during and following injury and offers some insights on injury prevention. The athletic training practice domains of prevention, clinical evaluation and diagnosis, treatment, and rehabilitation and reconditioning within the context of dance medicine are the general focus. In particular, issues relating to the rehabilitation of dancers are presented as they reflect the reasonable, objective practices of the health care profession.

During the past 3 decades, graft reconstruction of the anterior cruciate ligament (ACL) has become an accepted treatment for symptomatic ACL deficiency. The goal of surgery is to prevent joint instability, which may further damage articular cartilage and menisci. Graft failure is defined as pathologic laxity of the reconstructed ACL. The prevalence of recurrent instability after primary ACL reconstruction ranges from 1% to 8%. Early failures, those that occur within the first 6 months, often are secondary to poor surgical technique, failure of graft incorporation, or errors in rehabilitation. Late failures, those that occur more than 1 year after surgery, likely are related to new trauma and graft tearing. Other complications of ACL reconstruction include roof impingement, postoperative stiffness, tunnel widening due to cyst formation, iliotibial band friction syndrome, hardware failure, and infection. Magnetic resonance imaging is the preferred advanced imaging modality for the evaluation of symptomatic ACL graft reconstructions

BACKGROUND: The incidence of anterior cruciate ligament injuries among dancers is much lower than that among team sport athletes and no clear gender disparity has been reported in the dance population. Although numerous studies have observed differences in lower extremity landing biomechanics between male and female athletes, there is currently little research examining the landing biomechanics of male and female dancers. Comparing landing biomechanics within this population may help explain the lower overall anterior cruciate ligament injury rates and the lack of gender disparity. HYPOTHESIS: Due to the fact that dancers receive jump-specific and balance-specific training from a very young age, we hypothesized that there would be no gender differences in drop-landing biomechanics in professional dancers. STUDY DESIGN: Controlled laboratory study. METHODS: Kinematics and ground-reaction forces were recorded as 33 professional modern and ballet dancers (12 men and 21 women) performed single-legged drop landings from a 30-cm platform. Joint kinematics and kinetics were compared between genders. RESULTS: No gender differences in joint kinematics or kinetics were found during landings (multivariate analysis of variance: P = .490 and P = .175, respectively). A significant relationship was found between the age at which the dancers began training and the peak hip adduction angle during landing (r = .358, P = .041). CONCLUSION: In executing a 30-cm drop landing, male and female dancers exhibited similar landing strategies and avoided landing patterns previously associated with increased injury rates. CLINICAL RELEVANCE: Commonly reported biomechanical differences between men and women, as well as the gender disparity among athletes in the incidence of ACL injuries, may be the result of inadequate experience in proper balance and landing technique rather than intrinsic gender factors. Beginning jump-specific and balance-specific training at an early age may counteract the potentially harmful adaptations in landing biomechanics observed in female athletes after maturity.

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.

The initiation of pointe training for dance students should be determined after careful evaluation of a number of factors. These include: the dance student's stage of physical development; the quality of her (or his) trunk, abdominal and pelvic control ('core' stability); the alignment of her legs (hip-knee-ankle-foot); the strength and flexibility of her feet and ankles; and the duration and frequency of her dance training. For students who meet the requirements related to all of these factors, began ballet training at age eight or later, and who are taking ballet class at least twice per week, pointe work should be initiated in the fourth year of training. Students with poor core stability or hypermobility of the feet and ankles may require additional strengthening to allow them to safely begin pointe training. For those who are only taking ballet classes once per week, or who are not truly pre-professional, pointe training should be discouraged. No student with insufficient ankle and foot plantar flexion range of motion or with poor lower extremity alignment should be allowed to do pointe work