The science of rotator cuff tears: translating animal models to clinical recommendations using simulation analysis.

PURPOSE: The purpose of this article is to review basic science studies using various animal models for rotator cuff research and to describe structural, biomechanical, and functional changes to muscle following rotator cuff tears. The use of computational simulations to translate the findings from animal models to human scale is further detailed. METHODS: A comprehensive review was performed of the basic science literature describing the use of animal models and simulation analysis to examine muscle function following rotator cuff injury and repair in the ageing population. RESULTS: The findings from various studies of rotator cuff pathology emphasize the importance of preventing permanent muscular changes with detrimental results. In vivo muscle function, electromyography, and passive muscle-tendon unit properties were studied before and after supraspinatus tenotomy in a rodent rotator cuff injury model (acute vs chronic). Then, a series of simulation experiments were conducted using a validated computational human musculoskeletal shoulder model to assess both passive and active tension of rotator cuff repairs based on surgical positioning. CONCLUSION: Outcomes of rotator cuff repair may be improved by earlier surgical intervention, with lower surgical repair tensions and fewer electromyographic neuromuscular changes. An integrated approach of animal experiments, computer simulation analyses, and clinical studies may allow us to gain a fundamental understanding of the underlying pathology and interpret the results for clinical translation.

Isolated tears of the anterior cruciate ligament: over 30-year follow-up of patients treated with arthrotomy and primary repair.

BACKGROUND: Over 30 years ago, Feagin and Curl reported on the diagnosis and treatment of "isolated" injuries of the anterior cruciate ligament (ACL). The purpose of this study was to evaluate the long-term results of the patients initially diagnosed with tears of the ACL, with special emphasis on those treated with primary repair. HYPOTHESIS: Long-term results are unsatisfactory for open evaluation and treatment of ACL injuries with or without primary repair. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Follow-up was available on 34 of the original 57 patients (60%) who had ACL tears on evaluation by arthrotomy. The average age at the index procedure was 20 years, and average follow-up was 32 (range, 29-36) years. Twenty-five of the 26 complete ACL tears were treated with primary repair. None of the 8 partial tears was repaired. Evaluations included the subjective and symptom ratings of the International Knee Documentation Committee (IKDC) evaluation form, Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, and SANE rating. RESULTS: For the IKDC subjective score, 18 of 34 patients rated their knees as normal or nearly normal. The Lysholm scores averaged 70.1 (range, 20-100). The average SANE rating at 5 years was 74.8 (range, 49-110), and the current SANE rating averaged 68.9 (range, 10-100). The overall KOOS rating averaged 68.6 (range, 26.4-100). The Tegner activity score was 3.7. There was little difference between patients with unrepaired partial tears and those who had primary repairs. CONCLUSION: At more than 30-year follow-up, patients have decreased activity levels and an equal mix of acceptable and unacceptable outcomes. We were unable to identify any predictive factors that correlated with the results; however, subsequent meniscal surgery did correlate with poor results. The results at greater than 30 years reinforce the 5-year results that showed unsatisfactory results after the open evaluation and treatment of ACL injuries with or without repair.

Initial biomechanical properties of staple-anchor Achilles tendon allograft and interference screw bone-patellar tendon-bone autograft fixation for anterior cruciate ligament reconstruction in a cadaveric model.

PURPOSE: Anterior cruciate ligament (ACL) reconstruction is a common procedure that has a fairly high success rate. Despite such success, controversy exists with regard to fixation and graft type. The purpose of this study was to quantify the maximum load to failure for staple-anchor freeze-dried Achilles tendon allograft fixation compared with interference screw bone-pattelar tendon-bone autograft fixation at the time of insertion for ACL reconstruction. METHODS: Eleven pairs of cadaveric knees were prepared for ACL reconstruction by disarticulation before graft insertion. The tibia and femur were mounted separately onto an MTS machine and were loaded to failure in line with the tunnels. Femoral fixation for the allograft was provided by a staple anchor; tibial fixation was provided by a suture anchor. Titanium interference screws on the femoral and tibial sides provided autograft fixation. A paired t test was performed to compare mechanical testing results in the 2 groups. RESULTS: Mean maximum load to failure for the allograft was 58.7 N (range, 32.3 to 92.6 N) and 119.6 N (range, 82 to 165.9 N) for the femur and the tibia, respectively, compared with 228.2 N (range, 74.2 to 352 N) and 232.9 N (range, 65.1 to 553.1 N) for the autografts. This difference was statistically significant (P < .001) for femoral fixation, but it was not statistically significant for tibial fixation (P = .186). CONCLUSIONS: Soft tissue Achilles tendon allograft with staple fixation is a significantly weaker fixation construct when compared with autograft bone-patellar tendon-bone with interference screw fixation. CLINICAL RELEVANCE: This study shows significantly weaker fixation in the staple-alograft construct and yet this construct has had at least equivalent results over a 5-year time frame, indicating that rigid femoral fixation may not be a critical factor in long-term results.

Concussions in adolescent athletes.

A concussion is defined as a complex pathophysiologic process affecting the brain that is induced by traumatic biomechanical forces. Concussions are caused by a direct or indirect blow that leads to a graded set of syndromes characterized by functional rather than structural disturbances to the brain. Concussions are characterized by a wide variety of presenting symptoms, including loss of consciousness, amnesia, confusion, headache, and nausea. Concussions occur in patients participating in all levels of athletic activities, with most occurring in younger athletes. The evaluation of a patient with a concussion should include assessment of the airway, breathing, circulation, level of consciousness, orientation, memory, concentration, and neurologic function. Multiple grading scales and return to play guidelines have been published to assist the clinician in the treatment of patients with concussions. Diagnostic and treatment concerns include spinal cord injury, intracranial pathology, second impact syndrome, and long-term impairment of cognitive function. Computerized neuropsychologic testing is a new tool in the treatment of concussions. These tests measure memory, new learning, attention, and reaction time and should be used as an adjunct to other tools for clinical decision making. Published guidelines will assist in treatment decisions; however, it should be kept in mind that all concussions are unique injuries.

"Stingers" in adolescent athletes.

Brachial plexus injuries commonly occur in athletes participating in contact sports. The incidence of transitory brachial plexus injury is approximately 30% to 50% over the course of a high school, college, or professional football player's career. These injuries are called "stingers" or "burners" because of the associated tingling that occurs in the upper extremity after the injury. Brachial plexus injuries are poorly understood and sometimes are difficult to manage. Appropriate knowledge and understanding of these injuries along with prompt recognition, diagnosis, and treatment are essential for optimal care of the injured athlete and for the athlete's timely return to play. Most injuries occur by one of three mechanisms: traction, compression, or hyperextension and compression. Injuries are clinically classified as neurapraxia, neurapraxia/axonotmesis, and neurotmesis according to their symptomatology and the pattern of symptom resolution. Most injuries are either a neurapraxia or a neurapraxia/axonotmesis. Most athletes recover completely and can return to play after they are asymptomatic and have regained full sensation, strength, and range of motion. Protective equipment has been introduced to decrease the occurrence of stingers. Education of the athlete, the family, and coaches is important to help them to understand and to assist in managing these injuries.

Age-related loss of muscle mass and bone strength in mice is associated with a decline in physical activity and serum leptin.

The mechanisms underlying age-related loss of muscle and bone tissue are poorly understood but are thought to involve changes in sex hormone status, physical activity, and circulating levels of inflammatory cytokines. This study attempts to develop an animal model useful for evaluating these mechanisms in vivo. Male C57BL/6 mice were included for study at 3, 6, 12, 18, 24, and 29 months of age. Endocortical mineralizing surface, serum leptin, body weight, and percentage of body fat all increased between 6 and 12 months of age as activity level declined. Serum levels of the inflammatory marker IL-6 increased significantly after 12 months of age, following the observed increase in body weight and percent body fat. Hindlimb muscle mass declined significantly between 18 and 24 months of age, both absolutely and relative to total body mass, with a further decline ( approximately 15%) between 24 and 29 months. Loss of muscle mass after 18 months of age was accompanied by a significant increase in bone resorption, as indicated by serum pyridinoline cross-links, and a significant decrease in fat mass, serum leptin, bone strength, bone mineral density, and vertical cage activity. No significant changes in serum testosterone with aging were detected in the mice, as levels were essentially constant between 6 and 29 months. Our data show that mice lose a significant amount of muscle and bone tissue with age, and this loss of musculoskeletal tissue is accompanied by a drop in serum leptin and preceded by a significant decrease in physical activity.

Analysis of outcomes of anterior cruciate ligament repair with 5-year follow-up: allograft versus autograft.

PURPOSE: To prospectively compare outcomes of primary anterior cruciate ligament (ACL) reconstruction with either Achilles tendon allograft with soft-tissue fixation or standard bone-patellar tendon-bone autograft with interference screw fixation. TYPE OF STUDY: Prospective comparative case series. METHODS: A group of 41 patients who underwent soft-tissue allograft reconstruction and a group of 118 patients who underwent autograft bone-patellar tendon-bone reconstruction were included in the final results. Patients were evaluated preoperatively and postoperatively at 1 to 2 weeks, 6 weeks, 3 months, 6 months, and then annually for 5 years. Objective measures of outcome included KT-1000 measurements, range of motion, ligamentous integrity, thigh atrophy, and International Knee Documentation Committee score. Subjective evaluations included patient completion of 5 questionnaires documenting functional status, pain, and health-related quality of life: (1) the short-form McGill Pain Questionnaire, (2) a patient subjective assessment of knee function and symptoms, (3) a patient subjective assessment follow-up, (4) a knee pain scale, and (5) the RAND 36-Item Health Survey. Mixed models analysis of variance was used to compare the outcomes of the treatment groups using baseline values of the study variables as a covariate. RESULTS: Autograft patients reported significantly more pain on the bodily pain subscale of the RAND-36 than the allograft group at 1 week (P = .0006), 6 weeks (P = .0007), and 3 months (P = .0270). Autograft patients reported more pain than allograft patients on the McGill Pain Scale visual analog scale at 1 to 2 weeks (P < .0001) and 6 weeks (P = .0147). Patient assessment of function and symptoms showed that a higher proportion of patients reported normal or nearly normal knee function in the allograft group than in the autograft group at 3 months (33% v 14%, P = .0558, respectively). Fewer activity limitations were reported by allograft patients than autograft patients at 6 weeks (P = .0501), 3 months (P = .0431), and 6 months (P = .0014). After reconstruction, the allograft group displayed significantly more laxity in KT-1000 measurements at all time points than the autograft group (P = .0520). These measurements decreased over time for both groups (P < .0001). CONCLUSIONS: Five-year follow-up of patients undergoing ACL reconstruction with allograft versus autograft were compared objectively and subjectively. Both groups of patients achieved similar long-term outcomes. Overall, the allograft patients reported less pain at 1 and 6 weeks after surgery, better function at 1 week, 3 months, and 1 year, and fewer activity limitations throughout the follow-up period. LEVEL OF EVIDENCE: Level II, prospective cohort study.

Cost comparison of anterior cruciate ligament reconstruction: autograft versus allograft.

PURPOSE: To compare the economic costs associated with anterior cruciate ligament (ACL) reconstruction using either autograft or allograft. The surgical costs are reported, including charge categories, for each procedure. All operations were performed in the Southern United States of America. TYPE OF STUDY: Evaluation of cost data collected from a group of patients participating in a prospective, nonrandomized trial. METHODS: A total of 122 patients with ACL-deficient knees undergoing surgical reconstruction using either bone-patellar tendon-bone autograft (n = 86) or freeze-dried Achilles tendon allograft (n = 37) were analyzed (1 patient underwent 2 allograft reconstructions). Patient selection for groups was based on the physician performing the surgery (2 surgeons performed autografts and 1 performed allografts). Groups were compared with respect to age, sex, race, and occupation. Hospital charge data were retrieved from the billing department and divided into various categories for comparison of the 2 groups. RESULTS: The mean hospital charge for ACL reconstruction was 4,622 dollars for allograft and 5,694 dollars for autograft (P < .0001). Differences included increased operating room time and a greater likelihood of overnight hospitalization for autograft procedures. This was slightly offset by higher charges for operating room supplies for allograft reconstructions owing to the cost of the graft itself. CONCLUSIONS: Allograft reconstruction of the ACL was significantly less expensive than autograft bone-patellar tendon-bone reconstruction. Allograft ACL reconstruction is a less costly alternative to autograft reconstruction. LEVEL OF EVIDENCE: Level IV, economic analysis with no sensitivity analysis.

Coping with sports injuries: an examination of the adolescent athlete.

Forty-eight injured adolescent athletes completed questionnaires over 3 months after injury to assess psychosocial outcomes. Depressive symptoms decreased over time, and the lack of positive stress and high athletic identity were associated with early depressive symptoms after accounting for injury severity. Increased social support was associated with lower initial depressive symptoms.

Ice reduces edema. A study of microvascular permeability in rats.

BACKGROUND: Ice is applied following a soft-tissue injury on the basis of clinical information. This study investigates the relationship between ice therapy (cryotherapy) and edema by determining microvascular permeability before and after contusion with and without ice therapy and provides data supporting a reduction in edema following cryotherapy. METHODS: A dorsal microvascular chamber was created in rats to allow the direct examination of microvascular parameters in intact, pre-established microvascular beds of the cutaneous maximus muscle in conscious rats. The rats received a contusion or sham contusion and were treated with cryotherapy or were not treated. Microvascular permeability (edema) was assessed by measuring fluorescent-labeled albumin in the interstitial fluid before and after contusion. RESULTS: Microvascular permeability following contusion was significantly increased in the group that received the contusion without cryotherapy compared with that in the group that received the sham contusion without cryotherapy (control) (p < 0.001). When ice was applied fifteen minutes after the contusion for twenty minutes, microvascular permeability (edema) decreased significantly (p < 0.001) compared with that in the group that did not receive cryotherapy after contusion. Permeability was increased in the group that received cryotherapy following the contusion compared with that in the control group (p = 0.012), although the increase was not as great as that between the group that received the contusion without cryotherapy and the control group. Sham contusion with cryotherapy significantly reduced microvascular permeability compared with that in the control group (p = 0.004). Sham contusion without cryotherapy did not cause a significant change in the microvascular permeability of postcapillary venules after 300 minutes compared with baseline measurements. CONCLUSIONS: The application of ice significantly decreased microvascular permeability following striated muscle contusion. The results of this study demonstrated that microvascular permeability is increased following a contusion coincident with significant leukocyte-endothelial interactions. However, microvascular permeability was significantly reduced following cryotherapy, a treatment demonstrated to reduce the number of rolling and adherent leukocytes. This association suggests that the reduction in edema in injured skeletal muscle following cryotherapy may be due to a reduction in leukocyte-endothelial interactions.