Biomechanical analysis of an interference screw and a novel twist lock screw design for bone graft fixation.

BACKGROUND: Malpositioning of an anterior cruciate ligament graft during reconstruction can occur during screw fixation. The purpose of this study is to compare the fixation biomechanics of a conventional interference screw with a novel Twist Lock Screw, a rectangular shaped locking screw that is designed to address limitations of graft positioning and tensioning. METHODS: Synthetic bone (10, 15, 20lb per cubic foot) were used simulating soft, moderate, and dense cancellous bone. Screw push-out and graft push-out tests were performed using conventional and twist lock screws. Maximum load and torque of insertion were measured. FINDINGS: Max load measured in screw push out with twist lock screw was 64%, 60%, 57% of that measured with conventional screw in soft, moderate and dense material, respectively. Twist lock max load was 78% and 82% of that with conventional screw in soft and moderate densities. In the highest bone density, max loads were comparable in the two systems. Torque of insertion with twist lock was significantly lower than with conventional interference screw. INTERPRETATION: Based on geometric consideration, the twist lock screw is expected to have 35% the holding power of a cylindrical screw. Yet, results indicate that holding power was greater than theoretical consideration, possibly due to lower friction and lower preloaded force. During graft push out in the densest material, comparable max loads were achieved with both systems, suggesting that fixation of higher density bone, which is observed in young athletes that require reconstruction, can be achieved with the twist lock screw.

Trends in biological joint resurfacing.

The treatment of osteochondral lesions and osteoarthritis remains an ongoing clinical challenge in orthopaedics. This review examines the current research in the fields of cartilage regeneration, osteochondral defect treatment, and biological joint resurfacing, and reports on the results of clinical and pre-clinical studies. We also report on novel treatment strategies and discuss their potential promise or pitfalls. Current focus involves the use of a scaffold providing mechanical support with the addition of chondrocytes or mesenchymal stem cells (MSCs), or the use of cell homing to differentiate the organism's own endogenous cell sources into cartilage. This method is usually performed with scaffolds that have been coated with a chemotactic agent or with structures that support the sustained release of growth factors or other chondroinductive agents. We also discuss unique methods and designs for cell homing and scaffold production, and improvements in biological joint resurfacing. There have been a number of exciting new studies and techniques developed that aim to repair or restore osteochondral lesions and to treat larger defects or the entire articular surface. The concept of a biological total joint replacement appears to have much potential. Cite this article: Bone Joint Res 2013;2:193-9.

Arthroscopically assisted mini-open rotator cuff repairs. Functional outcome at 2- to 7-year follow-up.

The functional outcome of 22 consecutive patients with full-thickness rotator cuff tears repaired using an arthroscopically assisted technique was evaluated. The average follow-up was 39 months (24 to 80), and the average tear size was 3.5 cm (1 to 7). There were 14 men and 8 women, with a mean age of 56 years (29 to 80); 86% of patients (N = 19) were satisfied with the results of surgery and 95% (N = 21) had improvement of their symptoms. All patients had a statistically significant improvement in pain and active abduction in the scapular plane and in external rotation. Postoperative strength in external rotation and abduction averaged 95% and 97% of the contralateral shoulder, respectively. Preoperative duration of symptoms, strength, age, and tear size were found to be independent predictors of outcome. The average Constant and Murley score was 84 of 100, the average American Shoulder and Elbow Surgeons score was 81 of 100, and the average University of California, Los Angeles, score was 31 of 35. Our results show that an arthroscopically assisted repair of full-thickness, moderate-to-large rotator cuff tears using uniform surgical technique and rehabilitation protocols provides excellent outcome with regard to function, pain, and activities of daily living.

Arthroscopically assisted reconstruction of the anterior cruciate ligament: initial clinical experience and minimal 2-year follow-up comparing endoscopic transtibial and two-incision techniques.

The purpose of this study was to determine the outcome of endoscopic Anterior Cruciate Ligament (ACL) reconstruction and assess whether this technique modification offers any significant advantages over arthroscopically assisted reconstruction. A consecutive series of 90 athletically-active patients (67 males, 23 females) who underwent reconstruction for ACL deficiency using a patellar tendon autograft was retrospectively reviewed. The study group consisted of two treatment subgroups: Group 1-EA (Endoscopic-Assisted technique using no lateral femoral condylar incision) consisted of 45 patients with a mean age of 25 years (range 15 to 43 and Group 2-AA (Arthroscopic-Assisted technique using both anterior and lateral femoral condylar incisions) consisted of 45 patients with a mean age of 25 years (range 16 to 37). The study groups were evaluated at specific postoperative intervals with a mean follow-up in Group 1-EA of 30 months (range 24-37) and in Group 2-AA, 41 months (range 24 to 77). Serial KT-1000 results averaged 2 mm in both groups with 75% of Group 1-EA and 78% in Group 2-AA patients noted to have < or = 3 mm side-to-side differences. No statistically significant differences were noted for complications including patellofemoral pain, arthrofibrosis, harvest site pathology, or painful hardware. At ultimate follow-up however, this study suggests that both methods may result in similar and reproducible satisfactory outcome.

Critical analysis of knee ligament rating systems.

Sixty-five patients who consecutively underwent anterior cruciate ligament reconstruction were studied using four individual, categoric, knee score rating systems. Different results were noted at followup (mean, 35 months; range, 24 to 58) depending on the rating method used. Ali patients were graded using the Hospital for Special Surgery, Lysholm, Tegner activity, and Cincinnati Knee Ligament rating systems. The Cincinnati Knee Ligament rating individual scores were noted to be lower than the Hospital for Special Surgery and Lysholm scores for subjective and objective outcome assessment. The Hospital for Special Surgery and Lysholm scores did not correlate highly with the Cincinnati Knee Ligament rating final rating, but they did correlate with each other. The use of ligament rating scores tended to inflate results, particularly when raw scores were converted to overall categoric ratings (e.g., excellent, good). The Cincinnati Knee Ligament rating system correlates more highly with individual grading and most precisely defines outcome in athletically active patients. Sources of error may be introduced by a disproportionate combination of unrelated scores or by overrating low-activity-level individuals who avoid stressing their knees. Avoidance of data generalization remains the optimal method for studying anterior cruciate ligament surgery outcome.

Arthroscopically assisted anterior cruciate ligament reconstruction with the pes anserine tendons. Comparison of results in acute and chronic ligament deficiency.

Fifty anterior cruciate ligament-deficient knees treated consecutively with arthroscopically assisted reconstruction using a pes anserine tendon autograft were retrospectively studied. The mean followup was 36.7 months (range, 26 to 58). All patients had reconstruction with a double-stranded graft. The mean injury to surgery interval was 9.6 days in 22 patients (acute group) and 22.5 months in 28 patients (chronic group). Objective outcome, which was noted to be more optimal in the acute group, was better than subjective outcome in either group. Examination revealed 95% of patients treated acutely and 82% of those treated later to have 1+ or less Lachman test result (P < 0.036) and 96% of the acute group and 82% of the chronic group to have an absent pivot shift (P < 0.036). Eighty-eight percent of acutely treated patients had a KT-1000 result of < or = 3 mm, as compared to 61% of chronically treated patients (P < 0.001). Loss of range of motion was significantly greater in the acute group (P < 0.018). Using a strict overall rating system, patients reconstructed earlier were noted to have a better outcome compared to those after delayed reconstruction (P < 0.021). Cumulative meniscal injury appears to be the most significant contributing factor.

Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.

Fifteen chronic anterior cruciate ligament-deficient knees were arthroscopically reconstructed with a semitendinosus tendon polypropylene (STP) augmented composite graft. A comparison group of 28 reconstructions with the semitendinosus tendon (ST) but without augmentation was simultaneously reviewed. The mean follow-up in the STP group was 31 months (range of 24-42 months) and in the ST group it was 34 months (range 26-54 months). Both patient groups had similar age, sex, preinjury functional sports level, injury-to-surgery interval, and associated meniscal pathology. Good-to-excellent subjective results were reported in 86% of STP patients and 78% of ST patients, whereas 86% of the STP patients and 88% of the ST patients returned to sports activity. Objective examination revealed 73% of the STP group and 82% of the ST group to have a negative or 1+ Lachman test result. A negative pivot shift was noted at follow-up in 80% of the STP group and in 82% of the ST group. KT-1000 testing revealed 60% of the STP patients and 61% of the ST patients to have less than or equal to 3 mm of side-to-side difference. In the STP group there was no evidence of graft breakage, deep infections, or sterile effusions. Overall subjective and functional results were uniformly better than objective results in both patient groups. Analysis of subjective, objective, and functional results reveal no difference in outcome between the STP and the ST patient groups.

Primary repair with semitendinosus tendon augmentation of acute anterior cruciate ligament injuries.

A retrospective review of 72 acute ACL injuries in 70 athletically active patients (50 recreational and 20 competitive athletes) treated with primary repair and semitendinosus tendon augmentation was conducted (mean follow-up time, 38.5 months). All patients had open primary multiple loop depth-varying suture repair and semitendinosus tendon augmentation at a mean injury to surgery interval of 9.1 days. Fifty-one cases (70.8%) were supplemented with an extraarticular procedure consisting in all cases of an iliotibial band lateral sling reinforcement. All patients underwent 6 weeks of postoperative immobilization followed by a graduated rehabilitation regimen lasting a mean 7.2 months. In 22 of the ACL tears, no other associated injury could be defined at arthrotomy, while in 27, significant medial collateral ligament injuries were noted. Lateral meniscal injuries (24) were more commonly noted than medial meniscal injuries (19). Good to excellent subjective results were reported in 82%, while 77.1% returned to preinjury sport level and participation without limitation. One patient developed "giving way" symptoms and overall, only four patients did not return to sports participation. Objective examination revealed 93.1% to have a 1+ or less Lachman test and 86.1% to have a negative pivot shift. Of 60 knees tested, 93.3% had KT-1000 side-to-side difference values (measured at 25 degrees +/- 5 degrees of flexion with an 89 N load) of less than or equal to 3 mm of anterior displacement. A 100 point Hospital for Special Surgery ligament rating score was used with 25 points assigned to subjective, 45 points to objective, and 30 points to functional assessment. The mean score at followup was 93.1. Analysis of results in patients with or without an extraarticular reinforcement revealed no difference in objective outcome. The incidence of patellofemoral pain was 27.8%. Thirty knees had some degree of loss of range of motion. Loss of terminal flexion was noted in 29, while 5 had loss of terminal extension. No correlation could be found between patellofemoral pain and diminished range of motion. Generalized ligamentous laxity was found in 37.1% of the patients; this was not associated with a poor result. This study suggests that primary repair with semitendinosus tendon augmentation of acute ACL injuries with a graduated rehabilitation regimen provides good subjective, and excellent functional and objective, results in active patients that were followed for more than 3 years.

Bicycle-related accidents and injuries in a population of urban cyclists.

To gain a better understanding of urban bicycle-related accidents and injuries, 93 Manhattan cyclists were asked to fill out a questionnaire on the subject and the results of their responses were analyzed. They reported a total of 51 bicycle-related accidents and 59 injuries of varying degrees of severity. Although 42 percent declared they used safety helmets, head trauma was reported by 25 percent of the injured cyclists. Most were not wearing protective headgear at the time of their injury, however. Increased cycling mileage and length of time cycling were significantly associated with increased accident occurrence. Surprisingly, 47 percent of the accident victims cited themselves as being at fault for the accident in which they were injured.