Karen M. Sutton

Arthrofibrosis of the knee.

Abstract Better understanding of surgical timing, improved surgical technique, and advanced rehabilitation protocols has led to decreased incidence of motion loss after anterior cruciate ligament injury and reconstruction. However, motion loss from high‐energy, multiligament injuries continues to compromise functional outcome. Prevention, consisting of control of inflammation and early motion, remains the key element in avoiding motion loss. However, certain techniques, such as manipulation under anesthesia in conjunction with arthroscopic lysis of adhesions, are reliable treatment options. Open surgical débridement is rarely necessary and should be considered only as a salvage procedure. A greater understanding of the pathogenesis of arthrofibrosis and related inflammatory mediators may result in novel therapies for treating the patient with motion loss.

Anterior cruciate ligament rupture: differences between males and females.

&NA; The rate of anterior cruciate ligament (ACL) rupture is three times higher in female athletes than in male athletes. Intrinsic factors such as increased quadriceps angle and increased posterior tibial slope may predispose girls and women to ACL injury. Compared with males, females have smaller notch widths and smaller ACL cross‐sectional area; however, no conclusive correlation between ACL size and notch dimension exists, especially in relation to risk of ACL injury. Female athletes who land with the knees in inadequate flexion and in greater‐than‐normal valgus and external rotation are at increased risk of ACL injury. No conclusive link has been made between ACL injury and the menstrual cycle. Neuromuscular intervention protocols have been shown to reduce the rate of injury in girls and women. Females are more likely than males to have a narrow A‐shaped intercondylar notch, and special surgical considerations are required in such cases. Following ACL reconstruction, female athletes are more likely than male athletes to rupture the contralateral ACL; however, males and females are equally likely to rupture the reconstructed knee. Although self‐reported outcomes in the first 2 years following reconstruction are worse for females than for males, longer‐term studies demonstrate no difference between males and females.

Partial-thickness rotator cuff tears.

&NA; Partial‐thickness rotator cuff tears are not a single entity; rather, they represent a spectrum of disease states. Although often asymptomatic, they can be significantly disabling. Overhead throwing athletes with partial‐thickness rotator cuff tears differ with respect to etiology, goals, and treatment from older, nonathlete patients with degenerative tears. Pathogenesis of degenerative partial‐thickness tears is multifactorial, with evidence of intrinsic and extrinsic factors playing key roles. Diagnosis of partial‐thickness rotator cuff tears should be based on the patients symptoms together with magnetic resonance imaging studies. Conservative treatment is successful in most patients. Surgery generally is considered for patients with symptoms of sufficient duration and intensity. The role of acromioplasty has not been clearly delineated, but it should be considered when there is evidence of extrinsic causation for the partial‐thickness rotator cuff tear.

Surgical treatment of distal biceps rupture.

Rupture of the distal biceps tendon accounts for 10% of all biceps brachii ruptures. Injuries typically occur in the dominant elbow of men aged 40 to 49 years during eccentric contraction of the biceps. Degenerative changes, decreased vascularity, and tendon impingement may precede rupture. Although nonsurgical management is an option, healthy, active persons with distal biceps tendon ruptures benefit from early surgical repair, gaining improved strength in forearm supination and, to a lesser degree, elbow flexion. Biomechanical studies have tested the strength and displacement of various repairs; the suspensory cortical button technique exhibits maximum peak load to failure in vitro, and suture anchor and interosseous screw techniques yield the least displacement. Surgical complications include sensory and motor neurapraxia, infection, and heterotopic ossification. Current trends in postoperative rehabilitation include an early return to motion and to activities of daily living.

Comparison of Single- and Double-Bundle Anterior Cruciate Ligament Reconstructions in Restoration of Knee Kinematics and Anterior Cruciate Ligament Forces

Background: Anterior cruciate ligament (ACL) deficiency alters 6 degrees of freedom knee kinematics, yet only anterior translation and internal rotation have been the primary measures in previous studies. Purpose: To compare the 6 degrees of freedom knee kinematics and the graft forces after single- and double-bundle ACL reconstructions under various external loading conditions. Study Design: Controlled laboratory study. Methods: Ten human cadaveric knees were tested with a robotic testing system under 4 conditions: intact, ACL deficient, single-bundle reconstructed with a quadrupled hamstring tendon graft, and double-bundle reconstructed with 2 looped hamstring tendon grafts. Knee kinematics and forces of the ACL or ACL graft in each knee were measured under 3 loading conditions: an anterior tibial load of 134 N, a simulated quadriceps muscle load of 400 N, and combined tibial torques (10 N·m valgus and 5 N·m internal tibial torques) at 0°, 15°, 30°, 60°, and 90° of knee flexion. Results: The double-bundle reconstruction restored the anterior and medial laxities closer to the intact knee than the single-bundle reconstruction. However, the internal rotation of the tibia under the simulated quadriceps muscle load was significantly decreased when compared with the intact knee after both reconstructions, more so after double-bundle reconstruction (P < .05). The entire graft force of the double-bundle reconstruction was more similar to that of the intact ACL than that of the single-bundle reconstruction. However, the posterolateral bundle graft in the double-bundle reconstructed knee was overloaded as compared with the intact posterolateral bundle. Conclusion: The double-bundle reconstruction can better restore the normal anterior-posterior and medial-lateral laxities than the single-bundle reconstruction can, but an overloading of the posterolateral bundle graft can occur in a double-bundle reconstructed knee. Clinical relevance: Both single-bundle and double-bundle techniques cannot restore the rotational laxities and the ACL force distributions of the intact knee.

In Situ Forces in the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament Under Simulated Functional Loading Conditions

Background The in situ forces of the anteromedial (AM) and posterolateral bundles (PL) of the anterior cruciate ligament (ACL) under simulated functional loads such as simulated muscle loads have not been reported. These data are instrumental for improvement of the anatomical double-bundle ACL reconstruction. Hypothesis The load-sharing patterns of the 2 bundles are complementary under simulated muscle loads. Study Design Descriptive laboratory study. Methods Eight cadaveric knees in this study were sequentially studied using a robotic testing system. Each knee was tested under 3 external loading conditions including (1) a 134-N anterior tibial load; (2) combined rotational loads of 10 N·m of valgus and 5 N·m internal tibial torques; and (3) a 400-N quadriceps muscle load with the knee at 0°, 15°, 30°, 60°, and 90° of flexion. The in situ forces of the 2 bundles of ACL were determined using the principle of superposition. Results Under the anterior tibial load, the PL bundle carried peak loads at full extension and concurrently had significantly lower force than the AM bundle throughout the range of flexion (P < .05). Under the combined rotational loads, the PL bundle contributed to carrying the load between 0° and 30°, although less than the AM bundle. Under simulated muscle loads, both bundles carried loads between 0° and 30°. There was no significant difference between the 2 bundle forces at all flexion angles (P > .05). Conclusion Under externally applied loads, in general, the AM bundle carried a greater portion of the load at all flexion angles, whereas the PL bundle only shared the load at low flexion angles. The bundles functioned in a complementary rather than a reciprocal manner to each other. Clinical Relevance The data appear to support the concept that both bundles function in a complementary manner. Thus, how to re-create the 2 bundle functions in an ACL reconstruction should be further investigated.

Cyclooxygenase-2 Expression in Chondrosarcoma

Objective: In recent years it has become evident that tissue cyclooxygenase-2 (COX-2) may play a role in carcinogenesis and tumor malignancy. There is now a mounting body of information that strongly implies that COX-2 inhibitors may be of some value in the management of patients with carcinomas, and most recently several similar reports have appeared relating to sarcomas. Methods: The authors studied 32 samples of cartilage tumors from our tumor tissue bank for the presence of COX-2 by a Western blot technique. There were 29 patients from whom the samples were obtained, including 8 with enchondromas and 21 with chondrosarcomas. Results: Thirteen of the 24 chondrosarcoma samples and none of the 8 enchondromas were positive for COX-2. An attempt was made to correlate these results with clinical data including age, gender, staging according to the Musculoskeletal Tumor Society, anatomical site, ploidic pattern, presence of metastases and death rate but no statistically valid correlation could be found. Conclusion: It is evident that COX-2 may play some role in chondrosarcoma but not in the benign enchondroma and that further studies with COX-2 inhibitors are warranted.

Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft: can it restore normal knee joint kinematics?

Background Anatomical reconstruction techniques that can restore normal joint kinematics without increasing surgical complications could potentially improve clinical outcomes and help manage anterior cruciate ligament injuries more efficiently. Hypothesis Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft can more closely restore normal knee anterior-posterior, medial-lateral, and internal-external kinematics than can conventional single-bundle anterior cruciate ligament reconstruction. Study Design Controlled laboratory study. Methods Kinematic responses after single-bundle anterior cruciate ligament reconstruction and single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft were compared with the intact knee in 9 fresh-frozen human cadaveric knee specimens using a robotic testing system. Kinematics of each knee were determined under an anterior tibial load (134 N), a simulated quadriceps load (400 N), and combined torques (10 N·m valgus and 5 N·m internal tibial torques) at 0°, 15°, 30°, 60°, and 90° of flexion. Results Anterior tibial translations were more closely restored to the intact knee level after single-tunnel double-bundle reconstruction with anatomical placement of hamstring tendon graft than with a single-bundle reconstruction under the 3 external loading conditions. Under simulated quadriceps load, the mean internal tibial rotations after both reconstructions were lower than that of the anterior cruciate ligament—intact knee with no significant differences between these 3 knee conditions at 0° and 30° of flexion (P > .05). The increased medial tibial shifts of the anterior cruciate ligament—deficient knees were restored to the intact level by both reconstruction techniques under the 3 external loading conditions. Conclusion Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft can better restore the anterior knee stability compared with a conventional single-bundle reconstruction. Both reconstruction techniques are efficient in restoring the normal medial-lateral stability but overcorrect the internal tibial rotations. Clinical Relevance Single-tunnel double-bundle anterior cruciate ligament reconstruction with anatomical placement of hamstring tendon graft could provide improved clinical outcomes over a conventional single-bundle reconstruction.

Shoulder Injuries in Men’s Collegiate Lacrosse, 2004-2009

Background: Men’s lacrosse has been one of the fastest growing team sports in the United States, at both the collegiate and high school levels. Uniquely, it combines both continuous overhead and contact activity. Thus, an understanding of its injury epidemiology and mechanisms is vital. Shoulder injuries have been shown to be common in the sport, but thus far there has been no dedicated analysis of these injuries with which to better inform injury prevention strategies. Study Design: Descriptive epidemiology study. Methods: All athlete exposures (AEs) and shoulder injuries reported to the National Collegiate Athletic Association (NCAA) Injury Surveillance System for intercollegiate men’s lacrosse athletes from 2004-2005 through 2008-2009 were collected. Type of injury was documented and the injury incidence per 1000 AEs was calculated. Event type, injury mechanism, specific injury, outcome, and time lost were recorded. Statistical analysis was performed using 95% CIs, calculated based on a normal approximation to Poisson distribution. Results: There were a total of 124 observed shoulder injuries during 229,591 monitored AEs. With weights, this estimates 1707 shoulder injuries over 2,873,973 AEs, for an incidence of 0.59 per 1000 AEs (95% CI, 0.56-0.62). The incidence of shoulder injury during competition was 1.89 per 1000 AEs (95% CI, 1.76-2.02), compared with 0.35 per 1000 AEs (95% CI, 0.33-0.38) during practice. Acromioclavicular joint injuries were most common (0.29 per 1000 AEs; 95% CI, 0.27-0.31). Labral injuries and instability events were also frequent (0.11 per 1000 AEs; 95% CI, 0.10-0.13). Player-to-player contact caused 57% of all shoulder injuries, with 25% due to contact with the playing surface. The average time lost was 11.0 days, with 41.9% of all shoulder injuries requiring ≥10 days. Clavicle fractures and posterior shoulder dislocation were particularly severe, with no athletes returning to play during the same season. Conclusion: Shoulder injuries are common in NCAA men’s lacrosse and are an important source of lost playing time. Acromioclavicular injuries were the most frequent injury in this series, but labral and instability injuries were also common. In this increasingly popular contact sport, an understanding of the epidemiology and mechanism of shoulder injuries may be used to improve protective equipment and develop injury prevention.

The effect of ankle position on the static tension in the Achilles tendon before and after operative repair: a biomechanical cadaver study.

Background: We hypothesized that there no need to position the foot in plantarflexion after operative repair of an Achilles tendon rupture. Methods: In five fresh cadaver lower extremity specimens, the static tension in the Achilles tendon was measured as the ankle was sequentially dorsiflexed from 30, to 20, to 10, to 0 degrees of plantarflexion. The tendon was then transected and repaired using a modified Krakow locking loop suture technique. The tension in the tendon was again measured as the foot was sequentially dorsiflexed through the same range of motion: 30, to 20, to 10, to 0 degrees. The repair was then tensile tested to failure. Results: The intact Achilles tendons generated on average 10 N, 10 N, 15.8 N and 31.9.0 N of tension at 30, 20, 10, and 0 degrees of plantarflexion, respectively. After a modified Krakow locking loop repair, the tension across the repair site was 10 N, 11.46 N, 18.4 N, and 30.3 N at 30, 20, 10, and 0 degrees of plantarflexion. Thus, moving the ankle from 30 degrees to neutral placed an additional force of 21.9 N on the intact tendon and 20.3 N on the repaired tendon. The mean tensile strength of the modified Krakow repair was 598.6 N (range 167 1129 N). Conclusions: The tension in the repaired tendon at neutral position is only a small percentage (6.4%) of the strength of the tendon when operatively repaired by a modified Krakow locking loop suture technique. Clinical Relevance: Our results suggest that the ankle joint does not have to be positioned in plantarflexion after operative repair using the described technique.