Dean C. Taylor

Understanding and Preventing Noncontact Anterior Cruciate Ligament Injuries A Review of the Hunt Valley II Meeting, January 2005

The incidence of noncontact anterior cruciate ligament injuries in young to middle-aged athletes remains high. Despite early diagnosis and appropriate operative and nonoperative treatments, posttraumatic degenerative arthritis may develop. In a meeting in Atlanta, Georgia (January 2005), sponsored by the American Orthopaedic Society for Sports Medicine, a group of physicians, physical therapists, athletic trainers, biomechanists, epidemiologists, and other scientists interested in this area of research met to review current knowledge on risk factors associated with noncontact anterior cruciate ligament injuries, anterior cruciate ligament injury biomechanics, and existing anterior cruciate ligament prevention programs. This article reports on the presentations, discussions, and recommendations of this group.

Viscoelastic properties of muscle-tendon units The biomechanical effects of stretching

Most muscle stretching studies have focused on defin ing the biomechanical properties of isolated elements of the muscle-tendon unit or on comparing different stretching techniques. We developed an experimental model that was designed to evaluate clinically relevant biomechanical stretching properties in an entire muscle- tendon unit. Our objectives were to characterize the viscoelastic behavior of the muscle-tendon unit and to consider the clinical applications of these viscoelastic properties. Rabbit extensor digitorum longus and tibialis anterior muscle-tendon units were evaluated using methods designed to simulate widely used stretching tech niques. Additionally, the effects of varying stretch rates and of reflex influences were evaluated. We found that muscle-tendon units respond viscoelastically to tensile loads. Reflex activity did not influence the biomechani cal characteristics of the muscle-tendon unit in this model. Experimental techniques simulating cyclic stretching and static stretching resulted in sustained muscle-ten don unit elongations, suggesting that greater flexibility can result if these techniques are used in the clinical setting. With repetitive stretching, we found that after four stretches there was little alteration of the muscle- tendon unit, implying that a minimum number of stretches will lead to most of the elongation in repetitive stretching. Also, greater peak tensions and greater energy absorptions occurred at faster stretch rates, suggesting that the risk of injury in a stretching regimen may be related to the stretch rate, and not to the actual technique. All of these clinically important considera tions can be related to the viscoelastic characteristics of the muscle-tendon unit.

Persistent disability associated with ankle sprains: a prospective examination of an athletic population.

The purpose of this study was to examine a young athletic population to update the data regarding epidemiology and disability associated with ankle injuries. At the United States Military Academy, all cadets presenting with ankle injuries during a 2-month period were included in this prospective observational study. The initial evaluation included an extensive questionnaire, physical examination, and radiographs. Ankle sprain treatment included a supervised rehabilitation program. Subjects were reevaluated at 6 weeks and 6 months with subjective assessment, physical examination, and functional testing. The mean age for all subjects was 20 years (range, 17–24 years). There were 104 ankle injuries accounting for 23% of all injuries seen. There were 96 sprains, 7 fractures, and 1 contusion. Of the 96 sprains, 4 were predominately medial injuries, 76 were lateral, and 16 were syndesmosis sprains. Ninety-five percent had returned to sports activities by 6 weeks; however, 55% of these subjects reported loss of function or presence of intermittent pain, and 23% had a decrement of >20% in the lateral hop test when compared with the uninjured side. At 6 months, all subjects had returned to full activity; however, 40% reported residual symptoms and 2.5% had a decrement of >20% on the lateral hop test. Neither previous injury nor ligament laxity was predictive of chronic symptomatology. Furthermore, chronic dysfunction could not be predicted by the grade of sprain (grade I vs. II). The factor most predictive of residual symptoms was a syndesmosis sprain, regardless of grade. Syndesmosis sprains were most prevalent in collision sports. This study demonstrates that even though our knowledge and understanding of ankle sprains and rehabilitation of these injuries have progressed in the last 20 years, chronic ankle dysfunction continues to be a prevalent problem. The early return to sports occurs after almost every ankle sprain; however, dysfunction persists in 40% of patients for as long as 6 months after injury. Syndesmosis sprains are more common than previously thought, and this confirms that syndesmosis sprains are associated with prolonged disability.

Risk factors associated with noncontact injury of the anterior cruciate ligament: a prospective four-year evaluation of 859 West Point cadets.

Background: The causes of noncontact anterior cruciate ligament injury remain an enigma. Purpose: To prospectively evaluate risk factors for noncontact anterior cruciate ligament injuries in a large population of young athletic people. Study Design: Prospective cohort study. Methods: In 1995, 1198 new United States Military Academy cadets underwent detailed testing and many parameters were documented. During their 4-year tenure, all anterior cruciate ligament injuries that occurred were identified. Statistical analyses were used to identify the factors that may have predisposed the cadets to noncontact anterior cruciate ligament injuries. Results: Among the 895 cadets who completed the entire 4-year study, there were 24 noncontact anterior cruciate ligament tears (16 in men, 8 in women). Significant risk factors included small femoral notch width, generalized joint laxity, and, in women, higher than normal body mass index and KT-2000 arthrometer values that were 1 standard deviation or more above the mean. The presence of more than one of these risk factors greatly increased the relative risk of injury. All female cadets who had some combination of risk factors sustained noncontact anterior cruciate ligament injuries, indicating that some combinations of factors are especially perilous to the female knee. Conclusion: Several risk factors may predispose young athletes to noncontact anterior cruciate ligament injury.

Pathologic Changes Associated with Shoulder Dislocations Arthroscopic and Physical Examination Findings in First-Time, Traumatic Anterior Dislocations

This prospective observational study was performed on young patients, less than 24 years old, with first- time, traumatic anterior shoulder dislocations. These patients were offered either arthroscopic or nonopera tive treatment. Fifty-three patients chose nonoperative treatment. Sixty-three patients elected to have arthro scopic procedures. The average patient age was 19.6 years. There were 59 men and 4 women. All proce dures were performed within 10 days of dislocation. All 63 patients had hemarthrosis. Sixty-one of 63 (97%) patients treated surgically had complete detachment of the capsuloligamentous complex from the glenoid rim and neck (Perthes-Bankart lesion), with no gross evi dence of intracapsular injury. Of the other two patients, one had an avulsion of the inferior glenohumeral liga ment from the neck of the humerus, and one had an interstitial capsular tear adjacent to the intact glenoid labrum. Fifty-seven patients had Hill-Sachs lesions; none were large. There were six superior labral ante rior posterior lesions, two with detachment of the bi ceps tendon. There were no rotator cuff tears. Of the 53 nonoperatively treated patients, 48 (90%) have de veloped recurrent instability. In this population, the capsulolabral avulsion appeared to be the primary gross pathologic lesion after a first-time dislocation. These findings, associated with the 90% nonoperative recurrence rate, suggest a strong association between recurrent instability and the Perthes-Bankart lesion in this population.

Comparison of the Single Assessment Numeric Evaluation Method and Two Shoulder Rating Scales Outcomes Measures After Shoulder Surgery

The purpose of this study was to determine the correlation between the Single Assessment Numeric Evaluation method and the Rowe and American Shoulder and Elbow Surgeons scores. Between April 1993 and December 1996, 209 follow-up examinations were performed on 163 United States Military Academy cadets after shoulder surgery. These 209 examinations were divided into five follow-up categories: 3 months, 6 months, 1 year, 2 years, and greater than 2 years. The Rowe and American Shoulder and Elbow Surgeons scores from each subjects follow-up questionnaire were correlated with his or her Single Assessment Numeric Evaluation rating, which is determined by the subjects written response to the following question: “How would you rate your shoulder today as a percentage of normal (0% to 100% scale with 100% being normal)?” Correlation coefficients between the Single Assessment Numeric Evaluation and the two scores were 0.51 to 0.79 for the Rowe score and 0.46 to 0.69 for the American Shoulder Elbow Surgeons score. The results of this study indicate that the Single Assessment Numeric Evaluation correlates well with these two scores after shoulder surgery. This study suggests that this new evaluation method provides clinicians with a mechanism to gather outcomes data with little demand on their time and resources.

Graft size and patient age are predictors of early revision after anterior cruciate ligament reconstruction with hamstring autograft.

PURPOSE To evaluate whether decreased hamstring autograft size and decreased patient age are predictors of early graft revision. METHODS Of 338 consecutive patients undergoing primary anterior cruciate ligament (ACL) reconstruction with hamstring autograft, 256 (75.7%) were evaluated. Graft size and patient age, gender, and body mass index at the time of ACL reconstruction were recorded, along with whether subsequent ACL revision was performed. RESULTS The 256 patients comprised 136 male and 120 female patients and ranged in age from 11 to 52 years (mean, 25.0 years). The mean follow-up was 14 months (range, 6 to 47 months). Revision ACL reconstruction was performed in 18 of 256 patients (7.0%) at a mean of 12 months after surgery (range, 3 to 31 months). Revision was performed in 1 of 58 patients (1.7%) with grafts greater than 8 mm in diameter, 9 of 139 patients (6.5%) with 7.5- or 8-mm-diameter grafts, and 8 of 59 patients (13.6%) with grafts 7 mm or less in diameter (P = .027). There was 1 revision performed in the 137 patients aged 20 years or older (0.7%), but 17 revisions were performed in the 119 patients aged under 20 years (14.3%) (P < .0001). Most revisions (16 of 18) were noted to occur in patients aged under 20 years with grafts 8 mm in diameter or less, and the revision rate in this population was 16.4% (16 of 97 patients). Age less than 20 years at reconstruction (odds ratio [OR], 18.97; 95% confidence interval [CI], 2.43 to 147.06; P = .005), decreased graft size (OR, 2.20; 95% CI, 1.00 to 4.85; P = .05), and increased follow-up time (OR, 1.07; 95% CI, 1.02 to 1.12) were associated with increased risk of revision. CONCLUSIONS Decreased hamstring autograft size and decreased patient age are predictors of early graft revision. Use of hamstring autografts 8 mm in diameter or less in patients aged under 20 years is associated with higher revision rates. LEVEL OF EVIDENCE Level III, retrospective comparative study.

The Incidence and Characteristics of Shoulder Instability at the United States Military Academy

Background The literature provides little information detailing the incidence of traumatic shoulder instability in young, healthy athletes. Hypothesis Shoulder instability is common in young athletes. Study Design Descriptive epidemiologic study. Methods We prospectively captured all traumatic shoulder instability events at the United States Military Academy between September 1, 2004, and May 31, 2005. Throughout this period, all new traumatic shoulder instability events were evaluated with physical examination, plain radiographs, and magnetic resonance imaging. Instability events were classified according to direction, chronicity, and type (subluxation or dislocation). Subject demographics, mechanism of injury, and sport were evaluated. Results Among 4141 students, 117 experienced new traumatic shoulder instability events during the study period; 11 experienced multiple events. The mean age of these 117 subjects was 20.0 years; 101 students were men (86.3%), and 16 were women (13.7%). The 1-year incidence proportion was 2.8%. The male incidence proportion was 2.9% and the female incidence proportion was 2.5%. Eighteen events were dislocations (15.4%), and 99 were subluxations (84.6%). Of the 99 subluxations, 45 (45.5%) were primary events, while 54 (54.5%) were recurrent. Of the 18 dislocations, 12 (66.7%) were primary events, while 6 (33.3%) were recurrent. The majority of the 117 events were anterior in nature (80.3%), while 12 (10.3%) were posterior, and 11 (9.4%) were multidirectional. Forty-four percent (43.6%) of the instability events experienced were as a result of contact injuries, while 41.0% were a result of noncontact injuries, including 9 subluxations caused by missed punches during boxing; information was unavailable for the remaining 15%. Conclusion Glenohumeral instability is a common injury in this population, with subluxations comprising 85% of instability events.

Dynamic vs. static-stretching warm up: the effect on power and agility performance.

The purpose of this study was to compare the effect of a dynamic warm up (DWU) with a static-stretching warm up (SWU) on selected measures of power and agility. Thirty cadets at the United States Military Academy completed the study (14 women and 16 men, ages 18–24 years). On 3 consecutive days, subjects performed 1 of the 2 warm up routines (DWU or SWU) or performed no warm up (NWU). The 3 warm up protocols lasted 10 minutes each and were counterbalanced to avoid carryover effects. After 1–2 minutes of recovery, subjects performed 3 tests of power or agility. The order of the performance tests (T-shuttle run, underhand medicine ball throw for distance, and 5-step jump) also was counterbalanced. Repeated measures analysis of variance revealed better performance scores after the DWU for all 3 performance tests (p < 0.01), relative to the SWU and NWU. There were no significant differences between the SWU and NWU for the medicine ball throw and the T-shuttle run, but the SWU was associated with better scores on the 5-step jump (p < 0.01). Because the results of this study indicate a relative performance enhancement with the DWU, the utility of warm up routines that use static stretching as a stand-alone activity should be reassessed.

Prospective Evaluation of Arthroscopic Stabilization of Acute, Initial Anterior Shoulder Dislocations in Young Athletes Two- to Five-Year Follow-up

From March 1992 to November 1998, 57 patients sustained 58 acute, initial, traumatic anterior shoulder dislocations at the United States Military Academy. Six patients selected nonoperative treatment. Three patients underwent primary open repair after diagnostic arthroscopy revealed no Bankart lesion amenable to repair with the bioabsorbable tissue tack. The remaining 48 patients with 49 anterior dislocations were treated with arthroscopic primary repair. There were 45 men and 3 women with an average age of 20 years (range, 17 to 23) and an average follow-up of 37 months (range, 24 to 60). The average Rowe score was 92 (range, 30 to 100). The average single assessment numeric evaluation patient rating was 95.5% (range, 50% to 100%). The average Short Form-36 score (physical function) for the stable shoulders was 99 (range, 95 to 100). Forty-three shoulders remained stable (88%). There were six failures (12%). Factors associated with failure included a history of bilateral shoulder instability, a 2+ sulcus sign, and poor capsulolabral tissue at the time of repair. All patients with stable shoulders returned to their preinjury levels of athletic activity. With follow-up of 5 years, we have observed significantly better results compared with nonoperative treatment in young, active adults at the United States Military Academy.