Biodegradable interference screw augmentation reduces tunnel expansion after ACL reconstruction.

This study assessed 40 patients who underwent anterior cruciate ligament reconstruction with hamstring autografts using our standard technique. Twenty patients underwent tibial fixation augmentation with a biodegradable interference screw, and the remaining 20 patients did not. Patient groups were compared using radiographic evaluation of bone tunnel diameter, physical examination, and arthrometer measurements. The two groups differed in only one way: the placement of the tibial biodegradable interference screw. Biodegradable interference screw augmentation resulted in decreased distal tibial and some femoral tunnel diameters at both 3- and 12-month follow-up. There was no significant difference in the Lachman and arthrometer testing in either group of patients at the termination of this study. These results indicate that although distal tibia tunnel diameter reduction is significant, it does not appear to have any clinical significance in the first year.

Arthroscopic localization of medial collateral ligament injury: Report of 2 cases in adults.

Injury to the medial collateral ligament has previously been assessed primarily using the clinical examination and magnetic resonance imaging. In this article, we describe an adjunct to these diagnostic tools: an arthroscopic observation to assess the specific location of the medial collateral ligament injury.

Patella fracture after anterior cruciate ligament reconstruction with the patellar tendon: a comparison between different shaped bone block excisions.

Tensile failure of a patella after anterior cruciate ligament (ACL) reconstruction with autogenous patellar tendon graft is an uncommon but serious complication. One factor that may affect post-harvest patella strength is the shape of the bony defect. The effect of patella defect shape on ultimate tensile strength and mode of failure of the extensor mechanism has not been studied using physiologic moments. Twelve matched pair knee specimens were randomly distributed within three groups comparing rectangular versus triangular, rectangular versus circular, and circular versus triangular shaped patella defects. Specimens were loaded in tension to failure using physiologic moments. Patella fracture occurred in 21 of 24 specimens. Mean ultimate strength for all patellae with a circular defect was 2540 N (+/-651), rectangular defect was 3267 N (+/-920), and triangular defect was 3009 N (+/-1057). There was no significant difference in mean ultimate tensile strength between defect shapes or between matched pairs within the groups. Mode of failure also was similar in all three groups. No defect shape was found to be superior in this investigation comparing ultimate tensile strength or mode of failure between different shaped patella defects.

Development of the popliteomeniscal fasciculi in the fetal human knee joint.

PURPOSE: The purpose of this study is to better understand the function of the popliteomeniscal fasciculi and their relationship to the popliteus tendon and the lateral meniscus by describing these structures during embryonic development. TYPE OF STUDY: Anatomic dissection and histologic evaluation. METHODS: Twelve fresh-frozen lower extremity specimens (6 paired limbs) from second and third trimester human fetuses were obtained from spontaneous abortions. Each specimen was fixed in formalin and decalcified in 9.0% nitric oxide. The specimens were prepared by removal of all skin and most of the soft tissues before dissection of the lateral meniscus, parts of the posterolateral joint capsule, and the popliteus tendon and muscle. The right-side specimens were sectioned in the transverse plane, and the left-side specimens in the coronal plane. Histologic sections were prepared with H&E and Masson's trichrome stains. Light microscopy was used to evaluate the lateral meniscal attachment, with detailed attention to the popliteomeniscal fasciculi. RESULTS: The close interrelationship of lateral meniscus and popliteus tendon, especially during embryologic development, does give a better understanding how the fasciculi stabilize the lateral meniscus and allow the popliteus tendon to function as a retractor of the lateral meniscus. The fasciculi consist of 3 layers including a dense collagen layer, a vascular layer, and a synovial or capsular layer. CONCLUSIONS: During embryologic development, the fasciculi appeared to provide a vascular supply to the lateral meniscus adjacent to the popliteal hiatus where the meniscus is devoid of capsular attachments.

Simple anterior pelvic external fixation.

BACKGROUND: Unstable pelvic ring disruptions are often associated with significant morbidity and mortality, especially in patients with multiple injuries. Early pelvic fixation provides stability and should diminish ongoing hemorrhage. A simple anterior single-pin pelvic external fixator can be applied rapidly and accurately to stabilize pelvic ring injuries as a part of the initial patient resuscitation of such patients. Simple anterior pelvic external fixation (SAPEF) frames can be used as either temporary, definitive, or supplementary fixation depending on the pelvic injury pattern. METHODS: Over a 32-month period, 41 patients with unstable pelvic ring disruptions were stabilized using a simple anterior pelvic external fixator. Eight patients had open pelvic ring injuries and 13 others had genitourinary system disruptions. Fluoroscopic imaging was used to insert all of the fixation pins into the iliac crest between the iliac cortical tables to a depth of at least 5 cm. Each patient had closed manipulative reduction of the pelvic ring using external methods before SAPEF application. RESULTS: One patient died less than 24 hours after injury because of torrential hemorrhage. Clinical evaluations and serial radiographs, including postoperative computed tomographic scans, were available for the other 40 patients postoperatively. Seventy-five of the 80 (94%) pins were completely contained between the iliac cortical tables, according to the computed tomographic scans. The initial pelvic closed reductions were maintained until the fixators were removed in 37 of 40 patients (93%). Only one deep pin track infection developed, mandating early frame removal and intravenous antibiotic therapy. CONCLUSION: Simple anterior pelvic external fixation can be applied rapidly using fluoroscopic guidance to direct accurate pin insertion and closed manipulative reduction of the pelvis. Depending on the specific pelvic ring injury pattern and clinical scenario, SAPEF can serve as a resuscitative temporary fixation device, as definitive pelvic treatment, or as a supplement for pelvic internal fixation implants.

Tunnel expansion after hamstring anterior cruciate ligament reconstruction with 1-incision EndoButton femoral fixation.

In this study, we compared a study group of 20 patients who underwent anterior cruciate ligament (ACL) reconstruction with hamstring autografts using a 1-incision endoscopic technique verses a control group of 20 patients using a 2-incision technique. The patient groups were compared based on increase of bone tunnel diameter seen radiographically, physical examination, and arthrometer measurements. The 1-incision technique differed from the 2-incision technique in 2 ways: an EndoButton femoral fixation system and drilling of the femoral tunnel through the tibial tunnel (transtibial). This study shows that the majority of tunnel diameter measurements for the 1-incision ACL reconstruction technique were greater than those of the 2-incision ACL reconstruction technique using autologous hamstring tendons, at both 3 and 12 months of follow-up. Between 3 and 12 months follow-up, there was no statistical differences in tunnel enlargement between the 2 groups of patients. The measured tunnel enlargement, therefore, would have occurred before the 3-month follow-up. There was no significant difference in the Lachman or arthrometer testing in either group of patients at the termination of this study. This indicates that, although tunnel expansion is significant, the increased expansion is not related to increased knee laxity in the first year.

Irreducible posterolateral dislocation of the knee.

Traumatic knee dislocations are relatively rare, often associated with neurovascular injury, and almost always amenable to closed reduction. However, over the years, several authors have recognized that the rare knee dislocation not reducible by closed manipulation usually involves posterolateral dislocation of the tibia and button-holing of the medial femoral condyle through the medial retinaculum. These cases present with a dimple sign, a characteristic invagination of tissues at the medial joint line. Open reduction entails extraction of the soft-tissue collar that becomes incarcerated in the trochlea and intercondylar notch. We present an interesting case of irreducible posterolateral knee dislocation and review many of the salient points associated with this entity. Additionally, we include intraoperative video footage available on the Journal Web site to promote a better appreciation of the dramatic visual presentation and physical examination of this unusual injury.

Response of hamstring and patellar tendon grafts for anterior cruciate ligament reconstruction during cyclic tensile loading.

The efficacy of anterior cruciate ligament (ACL) reconstruction in the knee using hamstring tendon or patellar tendon grafts is thought to depend on the relative amounts of graft elongation, or creep, following postoperative rehabilitation. In this study, the creep responses of the tendinous portions of these two graft types were compared during 1 hour of cyclic loading to 200 N at 1 Hz. In the hamstring tendon grafts, strains were measured in both the tissue and in the length-augmentation tape to identify the relative contribution of this particular graft fixation to overall creep. Differences in tissue strain between graft types during cyclic loading were not statistically significant. For both types of grafts, overall graft length significantly increased after 3600 cycles while tissue creep was not significant. The greatest creep in the hamstring tendon grafts occurred at the tissue-tape interface, indicating a potential disadvantage of this composite graft construct.

Anterior cruciate ligament injuries in the skeletally immature patient.

Injuries of the anterior cruciate ligament (ACL) in children are more frequent than once thought. Special factors must be taken into consideration when treating ACL injuries in the skeletally immature patient. Risks of surgery must be weighed against potential damage to the knee caused by repeated injury. The authors prefer the use of both tibial and femoral centrally placed drill holes, hamstring tendon autografts, fixation distant from the physis, and avoidance of dissection near the physis. This technique will minimize damage to the physis and should not hinder normal growth.

Radiographic evaluation of glenohumeral kinematics: a muscle fatigue model.

The purpose of this study was to document the effect of muscle fatigue on glenohumeral kinematics. Twelve male volunteers without shoulder disease and with an average age of 27 years were studied. Glenohumeral anteroposterior radiographs were taken at 45 degrees intervals as the arm was abducted in the plane of the scapula from 0 degree to 135 degrees. This series of radiographs was performed both before and immediately after the subject performed a series of deltoid and rotator cuff fatiguing exercises. The average humeral head position or translation before and after muscle fatigue for each arm angle was compared. For all subjects, before fatigue, the position of the humeral head was below the center of the glenoid for all angles of abduction. There was essentially no change in position of the humeral head in the prefatigue state, as the arm was abducted from 0 degree to 135 degrees with no more than an average 0.3 mm of total humeral head excursion. After fatigue, excursion of the humeral head increased to an average of 2.5 mm between the tested positions. The position of the humeral head with the arm at 0 degree of abduction was lower or had migrated inferiorly compared with the rested state, with an average 1.2 mm significant increase in inferior translation. With the initiation of abduction, the humeral head demonstrated significant superior migration or translation in all positions tested. This result has important implications for conservative treatment of shoulder impingement and underscores the importance of rehabilitation to maximize the endurance and strength of the rotator cuff musculature.

The skeletally fixed knee hinge for the grossly unstable knee.

This study examined whether a skeletally fixed prefabricated knee hinge can provide the intact or unstable knee with normal motion through a specific arc of motion. Eight cadaveric knee specimens were used. The amount of motion mismatch between knee and hinge motion was evaluated at six different knee flexion angles. With all knee ligaments intact, addition of the hinge resulted in increasing amounts of joint compression with knee flexion. When all knee ligaments were cut, there was some degree of distraction with 0 degrees of knee flexion, which seemed to gradually decrease and become compressive at 80 degrees of flexion. These values were not statistically significant. In contrast, the mismatch between anterior and posterior tibial translation mismatch was statistically significant. With the ligaments intact, the addition of the hinge resulted in increased amounts of posterior tibial translation, which became significant at 80 degrees of flexion. Similarly, when the ligaments were cut with the hinge intact, there was an increasing amount of posterior tibial translation, which became significant at 60 degrees of flexion. There was also a significant amount of anterior tibial translation at 0 degrees in this group. These results indicate that the hinge allows only a limited range of motion that does not significantly alter tibial translation or joint compression or distraction. Whether this amount of motion is enough to improve the outcome of the grossly unstable knee is unknown. The use of a more sophisticated hinge system might accomplish a greater range of anatomic motion before significant mismatch occurs between hinge and knee motion.

Contact pressures at osteochondral donor sites in the knee.

The purposes of this study were to determine whether any of the commonly recommended osteochondral donor sites are nonarticulating throughout a functional range of knee motion, and to determine the differential contact pressures for these sites. Ten commonly recommended sites for osteochondral harvest were evaluated with pressure-sensitive film through a functional range of motion with a model that simulated nonweightbearing resistive extension of the knee. All 10 donor sites demonstrated a significant contact pressure through 0 degree to 110 degrees of knee motion. The different color density measurements between donor sites were also significant. Although donor sites 1, 2, 9, and 10 demonstrated significantly less contact pressure than the sites with the greatest contact pressure, the difference in mean pressures was small. No osteochondral donor site tested was free from contact pressure. It is currently unknown whether articular contact at these osteochondral donor sites will lead to degenerative changes or any other problems.

Interference screw position and hamstring graft location for anterior cruciate ligament reconstruction.

Anterior cruciate ligament reconstruction with hamstring tendon graft and interference screw fixation has recently been considered. Concerns for the use of interference screws with soft tissue grafts include damage to the graft during screw insertion, decreased fixation strength, and a decrease in the bone-tendon contact area for healing within the tunnel when the screw is placed in an eccentric position. This last concern could be addressed by placing the interference screw centrally between the four limbs of the hamstring graft. The purpose of this study was to determine the mode of failure, the pullout force, and graft slippage before graft fixation failure of hamstring tendons fixed with an interference screw positioned eccentrically in relation to the hamstring tendons verses an interference screw positioned centrally between the four graft limbs. The semitendinosus and gracilis tendons were harvested from six, fresh cadaveric specimens. Each tendon was divided into two segments of equal length. Both the semitendinosus and gracilis tendon segments were looped to form four strands. The specimens were then fixed with a bioabsorbable interference screw in the two different positions and pulled from a standardized polyurethane foam. All tendons in both groups failed by pulling out from between the interference screw and tunnel, regardless of the screw position. No tendon was cut by the screw in either group. There was no significant difference between the forces required to produce specific amounts of graft slippage between the two fixation techniques tested. There was no significant difference between the average total slippage at maximum pullout, 11.8 mm for the screw placed in the eccentric position and 13.7 mm for the screw placed in the central position. The maximum pullout force averaged 265.3 N for the screw placed in the eccentric position, and 244.7 N for the screw placed in the central position; these values were not significantly different. Placement of the interference screw in the central position did not compromise strength and it improves graft contact within the bone tunnel. Interference screw fixation, when applied against a bone plug, has been shown to consistently have a pullout force of more than 400 N.

Arthroscopic meniscal repair with fibrin clot of complete radial tears of the lateral meniscus in the avascular zone.

Peripheral lateral meniscal tears are amenable to arthroscopic meniscal repair. However, the posterolateral aspect of the lateral meniscus adjacent to the popliteus tendon is devoid of penetrating peripheral vessels and therefore difficult to heal. A complete radial split at this site is usually treated with total meniscectomy. We report five cases of a tear of the posterolateral aspect of the lateral meniscus anterior to the popliteus fossa. All patients had a radial split that extended to the popliteus tendon. In all cases, the repair was enhanced with a fibrin clot. Second-look arthroscopy showed that healing of the periphery occurred in all of the cases. All patients returned to their initial level of sports activity. Three of five patients were available for follow-up at an average of 71 months, and magnetic resonance imaging was performed at that time to assess the previously repaired meniscus. All menisci were fully healed and showed no further signs of degeneration. The ability of an exogenous fibrin clot to stimulate and support a reparative response in the avascular portion of the meniscus may represent a potential method of repair. Awareness of the relatively low healing potential of this zone and enhancement of healing opportunities should improve outcome.

Different regional healing rates with the outside-in technique for meniscal repair.

Fifty-one patients with meniscal repair using the outside-in technique were reassessed with second-look arthroscopic procedures (N = 15), arthrographic examination (N = 41), magnetic resonance imaging (N = 36), or a combination of these techniques. Forty-one medial and 10 lateral menisci were repaired. The average clinical follow-up was 15 months (range, 3 to 80). Forty-five of 51 patients had tears that were located in or extended into the posterior horn of the medial or lateral meniscus. Complete healing occurred in 23 menisci (45%), partial healing was observed in 16 (15 medial, 1 lateral) (32%), and no healing occurred in 12 (24%). Remarkably, in all 15 patients who had tears extending from the posterior to the middle third of the medial meniscus that were partially healed, it was always the posterior third that had not fully healed. This finding is statistically significant. In addition, the middle third of these menisci had not fully healed in five patients. No healing occurred in the two patients with tears in the posterior third of the medial meniscus. Poor healing with the outside-in technique was observed in patients with tears into the posterior horn of the medial meniscus. For tears in the middle and anterior portion of the medial meniscus, as well as all lateral meniscus tears, the outside-in technique is our current method of choice.