Michael J. Hulstyn

Decreased lubricin concentrations and markers of joint inflammation in the synovial fluid of patients with anterior cruciate ligament injury

OBJECTIVE To study the effect of anterior cruciate ligament (ACL) injury on lubricin concentrations in synovial fluid (SF) and its correlation with time postinjury, inflammatory cytokines, lubricin-degrading enzymes, and SF proteoglycan content. METHODS SF samples were obtained from both knees of 30 patients with unilateral ACL insufficiency, 32-364 days postinjury. Lubricin, inflammatory cytokines (interleukin-1beta [IL-1beta], tumor necrosis factor alpha [TNFalpha], and IL-6), and catabolic enzymes (procathepsin B and neutrophil elastase) were measured in SF from injured and contralateral (uninjured) joints, by enzyme-linked immunosorbent assay. Sulfated glycosaminoglycan (sGAG) levels in the SF were measured by Alcian blue binding assay. RESULTS SF lubricin concentrations were significantly (P < 0.001) reduced at an early stage following ACL injury when compared with those in the contralateral joint. Within 12 months, the lubricin concentration in the injured knee (slope = 0.006, SE = 0.00010, P < 0.001) approached that in the contralateral knee, which did not change with time (slope = -0.0002, SE = 0.00050, P = 0.71). TNFalpha levels showed a significant negative relationship with log2 lubricin levels. IL-1beta, TNFalpha, IL-6, procathepsin B, and neutrophil elastase concentrations in SF from injured knees were greater in samples from recently injured knees compared with those that were chronically injured. There were no detectable cytokines or enzymes in the SF of contralateral joints. Concentrations of sGAG were significantly (P = 0.0002) higher in the SF from injured knees compared with the contralateral joints. CONCLUSION The decrease in SF lubricin concentrations following ACL injury may place the joint at an increased risk of wear-induced damage as a consequence of lack of boundary lubrication, potentially leading to secondary osteoarthritis. The decrease in SF lubricin was associated with an increase in levels of inflammatory cytokines.

Biomechanical evaluation of interference screw fixation in a bovine patellar bone-tendon-bone autograft complex for anterior cruciate ligament reconstruction

A bovine model was developed for biomechanical evaluation of anterior cruciate ligament (ACL) reconstruction using patellar bone-tendon-bone (b-t-b) autograft to examine the differences in time zero fixation mechanical properties of different interference screw lengths and diameters. The surgical technique of interference screw fixation of the b-t-b complex performed clinically was reproduced in a controlled animal model. The femur-patellar tendon graft-tibia complex was tested with anterior displacement of the tibia in 30 degrees of knee flexion to allow examination of the femoral and tibial fixation properties simultaneously. The statistical model concurrently explored differences between screw length and diameter while accounting for variations between graft properties. No statistically significant differences were found between the 7- and 9-mm screws with respect to peak load or energy to failure when using a 10-mm triangular graft in a 10-mm tunnel. The 7- and 9-mm screws were superior to the 5.5-mm screws with respect to these same parameters. Based on our results, the 7-mm interference screws can be used with equal confidence as the 9-mm screw, and the 20-mm length can be similarly exchanged for 30-mm length for patellar b-t-b graft fixation.

Knee Laxity Does Not Vary With the Menstrual Cycle, Before or After Exercise

Background An intriguing explanation for the disproportionately high rate of anterior cruciate ligament injury in female athletes is that the structural properties of the anterior cruciate ligament are affected by the menstrual hormones. Whether this actually occurs, however, is the subject of ongoing debate. Hypotheses (1) Anterior cruciate ligament laxity is different in the follicular, ovulatory, and luteal phases of the menstrual cycle, and (2) exercise exacerbates the difference in anterior cruciate ligament laxity in the 3 phases. Methods Over the course of 10 weeks, repeated knee laxity measurements were taken on 27 high-level female athletes, before and after exercise. Point in the menstrual cycle was determined with charts of waking temperature and menstruation. The independent effects of menstrual phase and exercise were evaluated using generalized estimating equations. Results Data from 18 participants were included in the final analysis. There were no significant differences in anterior cruciate ligament laxity in any of the 3 menstrual phases, before or after exercise. Conclusions Anterior cruciate ligament laxity is not significantly different during the follicular, ovulatory, and luteal phases of the menstrual cycle, and bicycling exercise does not exacerbate or create any differences in anterior cruciate ligament laxity.

The Effect of Protective Football Equipment on Alignment of the Injured Cervical Spine Radiographic Analysis in a Cadaveric Model

No universally accepted management protocol is avail able for dealing with the protective equipment worn by a neck-injured football player. The purpose of this ca daveric study was to determine the effects of the hel met and shoulder pads on the alignment of 1) the intact lower cervical spine and 2) the partially destabilized C5-6 motion segment. In Group I cadavers (N = 15), the lower cervical spine was tested in an intact condi tion. In Group II (N = 8), the C5-6 motion segment was tested in both an intact and a partially destabilized condition. Each cadaver was placed supine on a back- board and four lateral cervical radiographs were ob tained as follows: no protective equipment, helmet only, helmet and shoulder pads, and shoulder pads only. Results for Group I showed that wearing both helmet and shoulder pads did not result in a significant change in cervical lordosis when compared with the neutral position (i.e., the no-equipment test). Cervical lordosis was significantly decreased in the helmet-only category (mean, 9.6°) and significantly increased in the shoulder pads-only category (mean, 13.6°). In Group II, destabilized specimens under the helmet test situa tion showed a significant mean increase in C5-6 for ward angulation (16.5°), posterior disk space height (3.8 mm), and dorsal element distraction (8.3 mm). Immobilizing the neck-injured football player with only the helmet or only the shoulder pads in place violates the principle of splinting the cervical spine in neutral alignment, according to our findings. We support the concept that removal of the helmet and shoulder pads should be an all-or-none proposition.

The meniscal roots: gross anatomic correlation with 3-T MRI findings.

OBJECTIVE The purpose of this article is to highlight the normal anatomic features of the meniscal roots on photographs of dissected cadaveric knee specimens and 3-T MR images. CONCLUSION The meniscal roots, which are critical attachment sites of the medial and lateral menisci to the central tibial plateau, are well-visualized on intermediate-weighted, turbo spin-echo 3-T MRI and can be identified in proximity to the tibial insertions of the anterior and posterior cruciate ligaments.

Shoulder injuries in the athlete.

Musculoskeletal injuries constantly provide challenges to the team physician, including those to the shoulder. Shoulder injuries are common in athletes, whether as a result of direct contact from a collision or from repetitive overhead motion. This article reviews sports-related injuries to the shoulder, including similarities between sports, clinical evaluation, and rehabilitation of the athletes.

Effects of Initial Graft Tension on the Tibiofemoral Compressive Forces and Joint Position After Anterior Cruciate Ligament Reconstruction

Background The initial tension applied to an anterior cruciate ligament graft at the time of fixation modulates knee motion and the tibiofemoral compressive loads. Purpose To establish the relationships between initial graft tension, tibiofemoral compressive force, and the neutral tibiofemoral position in the cadaveric knee. Study Design Controlled laboratory study. Methods The tibiofemoral compressive forces and joint positions were determined in the anterior cruciate ligament-intact knee at 0°, 20°, and 90° of knee flexion. The anterior cruciate ligament was excised and reconstructed with a patellar tendon graft using graft tensions of 1, 15, 30, 60, and 90 N applied at 0°, 20°, and 90° of knee flexion. The compressive forces and neutral positions were compared between initial tension conditions and the anterior cruciate ligament-intact knee. Results Increasing initial graft tension increased the tibiofemoral compressive forces. The forces in the medial compartment were 1.8 times those in the lateral compartment. The compressive forces were dependent on the knee angle at which the tension was applied. The greatest compressive forces occurred when the graft was tensioned with the knee in extension. An increase in initial graft tension caused the tibia to rotate externally compared with the anterior cruciate ligament-intact knee (1.5° and 7.7° of external rotation when tensioned to 90 N at 0° and 90° of knee flexion, respectively). Increases in initial graft tension also caused a significant posterior translation of the tibia relative to the femur (0.9 and 5.3 mm of posterior translation when tensioned to 90 N at 0° and 90° of knee flexion, respectively). Conclusion Different initial graft tension protocols produced predictable changes in the tibiofemoral compressive forces and joint positions. Clinical Relevance The tibiofemoral compressive force and neutral joint position were best replicated with a low graft tension (1-15 N) when using a patellar tendon graft.

Evolution of the treatment options of ulnar collateral ligament injuries of the elbow

Ulnar collateral ligament (UCL) insufficiency is potentially a career threatening, or even a career ending, injury, particularly in overhead throwing athletes. The evolution of treating modalities provides afflicted athletes with the opportunity to avoid premature retirement. There have been several clinical and basic science research efforts which have investigated the pathophysiology of UCL disruption, the biomechanics specific to overhead throwing, and the various types of treatment modalities. UCL reconstruction is currently the most commonly performed surgical treatment option. An in depth analysis of the present treatment options, both non-operative and operative, as well as their respective results and biomechanical evaluation, is lacking in the literature to date. This article provides a comprehensive current review and comparative analysis of these modalities. Over the last 30 years there has been an evolution of the original UCL reconstruction. Yet, despite the variability in modifications, such as the docking technique, interference screw fixation, and use of suture anchors, the unifying concepts of UCL reconstruction are that decreased dissection of the flexor-pronator mass and decreased handling of the ulnar nerve leads to improved outcomes.

Delayed Gadolinium-Enhanced MR Imaging of Cartilage (dGEMRIC) following ACL injury

OBJECTIVE Early detection of glycosaminoglycan (GAG) loss may provide insight into mechanisms of cartilage damage in the anterior cruciate ligament (ACL)-injured patient. We hypothesized that tibial and femoral Delayed Gadolinium-Enhanced MR Imaging of Cartilage (dGEMRIC) indices would be lower in the medial compartment of the ACL-injured knee than in the contralateral, uninjured knee, and that scan order (i.e., whether the injured or the uninjured knee was imaged first) would not affect the indices. METHODS 15 subjects with unilateral ACL injuries received a double dose of gadolinium [Gd(DTPA)(2-)] intravenously. After 90 min, both knees were sequentially imaged. The injured knee was scanned first in the odd-numbered subjects and second in the even-numbered subjects. The dGEMRIC indices of the median slice of the medial compartment were determined using the MRIMapper software. Index comparisons were made between knee status (ACL-injured vs uninjured), scan order (ACL-injured first vs uninjured first), and cartilage location (tibia vs femur) using a mixed model. RESULTS There was a significant difference in the mean dGEMRIC indices of the medial compartment between injured and uninjured knees (P<0.007). On average, there was a 13% decrease in the dGEMRIC index of the injured knee compared to the uninjured knee. There were no significant effects due to test order (P=0.800) or cartilage location (P=0.439). CONCLUSIONS The results demonstrate lower GAG concentrations in the medial compartment of the femoral and tibial articular cartilage of the ACL-injured knee when compared to the contralateral uninjured knee. The dGEMRIC indices were not sensitive to scan order; thus, sequential imaging of both knees is possible in this patient population.

Exercise-induced loss of bone density in athletes.

&NA; In athletes, the rarely identified malady of osteoporosis differs from other chronic effects of exercise. The most obvious difference is that hormonal imbalance leads to compensatory mechanisms that in turn lead to osteoporosis and increased incidence of fracture. Most research on this subject has dealt with women, because hormonal imbalances in women are easier to detect than those in men. Endurance athletes are known to have decreased levels of sex hormones, which can cause physiologic changes that lead to bone loss. This may result in relative osteoporosis despite the loading of the bone during exercise, which would normally increase bone mineral density. Premature osteoporosis may be irreversible, causing young athletes to become osteoporotic at an earlier age and have an increased risk of fracture later in life.