Faculty Bibliography

PURPOSE: To determine the effect of insertion angle, from 45 degrees to 135 degrees in 15 degrees increments, on the number of cycles withstood, the ultimate pullout strength, and the stiffness of threaded suture anchors subjected to load. METHODS: Threaded anchors were inserted into polyurethane foam at angles from 45 degrees to 135 degrees , in 15 degrees increments, relative to the direction of pull. Five anchors were tested at each angle. The anchors were first cycled for 30 cycles (10 each at 100 N, 150 N, and 200 N). The surviving specimens were then tensioned to failure. The McNemar test was used to compare cyclic failure rates. Paired-samples t tests were used to compare load-to-failure (LTF) and stiffness data. All P values are multiplicity adjusted by the Hommel procedure. RESULTS: Four of 5 anchors inserted at 45 degrees failed during cyclic testing at a mean of 27 cycles (P = .13). One of 5 anchors placed at 60 degrees failed after 29 cycles (P = .99). All other anchors survived cyclic testing. Mean LTF was 234 N, 243 N, 297 N, 373 N, 409 N, 439 N, and 417 N at insertion angles of 45 degrees , 60 degrees , 75 degrees , 90 degrees , 105 degrees , 120 degrees , and 135 degrees , respectively. LTF was significantly less for the 60 degrees group when compared with the 90 degrees , 105 degrees , 120 degrees , and 135 degrees groups (P < .05). LTF was significantly less for the 75 degrees group when compared with the 105 degrees , 120 degrees , and 135 degrees groups (P < .05). For the 90 degrees group, LTF was only significantly less when compared with the 135 degrees group (P = .022). The differences in LTF between the 105 degrees , 120 degrees , and 135 degrees groups were not significant. Stiffness increased from 28.13 N/mm at 90 degrees to 43.4 N/mm at 105 degrees (P = .03), 61.48 N/mm at 120 degrees (P = .003), and 86.83 N/mm at 135 degrees (P = .008). CONCLUSIONS: Anchors placed at more acute angles, that is, anchors placed closer to the so-called deadman's angle, failed at lower loads and provided less construct stiffness than anchors placed at angles greater than 90 degrees . Stiffness also increased sequentially from an angle of insertion of 90 degrees up to our maximum angle tested of 135 degrees . For threaded metallic suture anchors, an obtuse insertion angle of 90 degrees to 135 degrees in relation to the line of pull of the suture and rotator cuff withstands a greater LTF and provides a stiffer construct than the more acute insertion angle advocated by the "deadman theory." CLINICAL RELEVANCE: This study offers a biomechanical validation for optimal placement of threaded suture anchors at an angle of 90 degrees or more, as anatomic restraints allow, from the vector of pull of the attached suture and rotator cuff, rather than the 45 degrees angle recommended by the deadman theory.

Anterior cruciate ligament injury affects roughly 120 000 athletes in the United States every year. One of the most common techniques is the use of a bone-patellar tendon-bone graft. Graft harvest creates a sizeable defect in the remaining patellar tendon. Closure of this defect is based on surgeon preference. To date there has been no study on the effects of defect closure on the mechanical properties of remaining donor patellar tendon. The goal of this study was to investigate the effect of closure on both the strength and stiffness of the remaining patellar tendon. 7 pairs of fresh frozen cadaver patellar tendons were matched by tendon dimensions. Bone-patellar tendon-bone grafts were harvested from all of the specimens and then half of the paired tendons underwent defect closure. All of the donor tendons were then tested in a servohydraulic load frame to failure at a constant displacement rate at room temperature. This study found no differences in the load at failure, the engineering failure stress, stiffness or in the engineering modulus between the donor tendons that underwent defect closure versus those that did not.

BACKGROUND: Little is known about the role that a torn superior labrum (SLAP) plays in glenohumeral stability after biceps tenodesis. This biomechanical study evaluated the contribution of a type II SLAP lesion to glenohumeral translation in the presence of biceps tenodesis. The authors hypothesize that subsequent to biceps tenodesis, a torn superior labrum does not affect glenohumeral stability and therefore does not require anatomic repair in an overhead throwing athlete. METHODS: Baseline anterior, posterior, and abduction and maximal external rotation glenohumeral translation data were collected from 20 cadaveric shoulders. Translation testing was repeated after the creation of anterior (n = 10) and posterior (n = 10) type II SLAP lesions. Translation re-evaluation after biceps tenodesis was performed for each specimen. Finally, anatomic SLAP lesion repair and testing were performed. RESULTS: Anterior and posterior SLAP lesions led to significant increases in glenohumeral translation in all directions (P < .0125). Biceps tenodesis showed no significance in stability compared with SLAP alone (P > .0125). Arthroscopic repair of anterior SLAP lesions did not restore anterior translation compared with the baseline state (P = .0011) but did restore posterior (P = .823) and abduction and maximal external rotation (P = .806) translations. Repair of posterior SLAP lesions demonstrated no statistical difference compared with the baseline state (P > .0125). CONCLUSIONS: With no detrimental effect on glenohumeral stability in the presence of a SLAP lesion, biceps tenodesis may be considered a valid primary or revision surgery for patients suffering from symptomatic type II SLAP tears. However, biceps tenodesis should be considered with caution as the primary treatment of SLAP lesions in overhead throwing athletes secondary to its inability to completely restore translational stability.

BACKGROUND: The current study evaluated the outcomes of biologic resurfacing of the glenoid using a lateral meniscus allograft or human acellular dermal tissue matrix at intermediate-term follow-up. METHODS: Forty-five patients (mean age, 42.2 years) underwent biologic resurfacing of the glenoid, and 41 were available for follow-up at a mean of 2.8 years. Lateral meniscal allograft resurfacing was used in 31 patients and human acellular dermal tissue matrix interposition in 10. Postoperative range of motion and clinical outcomes were assessed at the final follow-up. RESULTS:: The overall clinical failure rate was 51.2%. The lateral meniscal allograft cohort had a failure rate of 45.2%, with a mean time to failure of 3.4 years. Human acellular dermal tissue matrix interposition had a failure rate of 70.0%, with a mean time to failure of 2.2 years. Overall, significant improvements were seen compared with baseline with respect to the visual analog pain score (3.0 vs 6.3), American Shoulder and Elbow Surgeons score (62.0 vs 36.8), and Simple Shoulder Test score (7.0 vs 4.0). Significant improvements were seen for forward elevation (106 degrees to 138 degrees ) and external rotation (31 degrees to 51 degrees ). CONCLUSION: Despite significant improvements compared with baseline values, biologic resurfacing of the glenoid resulted in a high rate of clinical failure at intermediate follow-up. Our results suggest that biologic resurfacing of the glenoid may have a minimal and as yet undefined role in the management of glenohumeral arthritis in the young active patient over more traditional methods of hemiarthroplasty or total shoulder arthroplasty.

OBJECTIVE: To assess the ability of 3D MR shoulder reconstructions to accurately quantify glenoid bone loss in the clinical setting using findings at the time of arthroscopy as the gold standard. MATERIALS AND METHODS: Retrospective review of patients with MR shoulder studies that included 3D MR reconstructions (3D MR) produced using an axial Dixon 3D-T1W-FLASH sequence at our institution was conducted with the following inclusion criteria: history of anterior shoulder dislocation, arthroscopy (OR) performed within 6 months of the MRI, and an estimate of glenoid bone loss made in the OR using the bare-spot method. Two musculoskeletal radiologists produced estimates of bone loss along the glenoid width, measured in mm and %, on 3D MR using the best-fit circle method, which were then compared to the OR measurements. RESULTS: There were a total of 15 patients (13 men, two women; mean age, 28, range, 19-51 years). There was no significant difference, on average, between the MRI (mean 3.4 mm/12.6 %; range, 0-30 %) and OR (mean, 12.7 %; range, 0-30 %) measurements of glenoid bone loss (p = 0.767). A 95 % confidence interval for the mean absolute error extended from 0.45-2.21 %, implying that, when averaged over all patients, the true mean absolute error of the MRI measurements relative to the OR measurements is expected to be less than 2.21 %. Inter-reader agreement between the two readers had an IC of 0.92 and CC of 0.90 in terms of percentage of bone loss. CONCLUSIONS: 3D MR reconstructions of the shoulder can be used to accurately measure glenoid bone loss.

Patellar instability is a complex pathoanatomical phenom- enon that requires an intricate understanding in order to properly treat patients. Often, the etiology of this entity is multifactorial, combining a series of physiologic and anatomic variables. A thorough history and physical as well as correct radiographic examinations are critical in both establishing the diagnosis and instituting the correct treatment. Non-operative management of recurrent insta- bility has a high failure rate. Current operative techniques have been shown to be instrumental in correcting anatomic abnormalities, reducing symptoms of instability, and giving patients an appropriate chance of returning to their previous level of activity.

Distal biceps ruptures occur most commonly in middle-aged males and result from eccentric contraction of the biceps tendon. The injury typically presents with pain and a tearing sensation in the antecubital fossa with resultant weakness in flexion and supination strength. Physical exam maneuvers and diagnostic imaging aid in determining the diagnosis. Nonoperative management is reserved for elderly, low demand patients, while operative intervention is generally pursued for younger patients and can consist of nonanatomic repair to the brachialis or anatomic repair to the radial tuberosity. Anatomic repair through a one-incision or two-incision approach is commonplace, while the nonanatomic repairs are rarely performed. No clear advantage exists in operative management with a one-incision versus two-incision techniques. Chronic ruptures present a more difficult situation, and allograft augmentation is often necessary. Common complications after repair include transient nerve palsy, which often resolves, and heterotopic ossification. Despite these possible complications, most studies suggest that better patient outcomes are obtained with operative, anatomic reattachment of the distal biceps tendon.

BACKGROUND: Anterior cruciate ligament reconstruction (ACLR) has traditionally been reserved for young patients with functional instability. As the aging population continues to grow and embrace a more active lifestyle, it is important to determine if favorable outcomes of ACLR can be achieved in older adults. METHODS: Patients greater than 50 years of age undergo- ing ACLR between January 2001 and September 2006 were identified. Charts were retrospectively reviewed for clinical, pathologic, and radiographic findings. Prospective data was collected at follow-up, including Lysholm Knee Score, Tegner Activity Level Score, International Knee Documenta- tion Committee (IKDC) Subjective Knee Form Score, and Knee Injury and Osteoarthritis Outcome Score (KOOS). Anteroposterior (AP) instability was assessed with use of a KT-2000 arthrometer (MEDmetric, San Diego, CA). RESULTS: Forty-seven patients underwent ACLR with 32 (16 males and 16 females) available at a mean follow-up of 5.0 years (range: 2.2 to 9.0 years). The mean age at the time of operation was 58.4 years (range: 51 to 65 years). At time of final follow-up, the mean side-to-side difference measured by KT-2000 was 1.2 +/- 1.3 mm (range: 0 to 4.5 mm). Mean postoperative subjective IKDC score was 80.1 (range: 33 to 100) and Lysholm score was 86.7 (range: 45 to 95). There was no change in Tegner score from pre-injury (range: 0 to 3) to postoperative (range: 0 to 3). Twelve patients (38%) underwent subsequent knee surgery. All patients were sat- isfied with the final outcome of their ACLR surgery. Only patellofemoral Outerbridge cartilage grade was associated with worse outcome. CONCLUSION: ACLR provides symptomatic relief and restoration of function for patients greater than 50 years of age. ACLR should be considered in active older patients with subjective functional instability.