Faculty Bibliography

Total shoulder arthroplasty is a common treatment for glenohumeral arthritis. One of the most common failure modes of total shoulder arthroplasty is glenoid loosening, causing postoperative pain, limitation of function, and potentially, the need for revision surgery. The literature has devoted considerable attention to the design of the glenoid component; efforts to better understand the biomechanics of the reconstructed glenohumeral joint and identify factors that contribute to glenoid component loosening are ongoing. This article reviews the current state of knowledge about the glenoid in total shoulder arthroplasty, summarizing the anatomic parameters of the intact glenoid, variations in component design and fixation, the mechanisms of glenoid loosening, the outcomes of revision surgery in the treatment of glenoid component failure, and alternative treatments for younger patients

Intra-articular hyaluronic acid viscosupplementation is gaining popularity as a treatment option in the nonoperative management of patients with osteoarthritis. Recent clinical studies have demonstrated that the anti-inflammatory, anabolic, and chondroprotective actions of hyaluronic acid reduce pain and improve patient function. With evidence mounting in support of the efficacy of this treatment modality for patients with osteoarthritis, its potential use in additional patient populations and for other pathologies affecting the knee is being investigated. The current article reviews the use of intra-articular hyaluronic acid viscosupplementation in the management of knee osteoarthritis and presents the potential for expanding its indications for other joints and alternative patient subpopulations. Additionally, future directions for the use of hyaluronic acid and areas of active research are discussed

Geriatric hip fracture management requires a specialized treatment algorithm secondary to the complex medical and social needs of this patient demographic. The overall goal of the treatment is early mobilization, in an effort to prevent the complications associated with prolonged recumbency and to return the patient to functional activity. There is near-universal agreement among orthopedic surgeons that fractures about the hip require operative fixation, but surgical management in this patient population brings with it a set of issues that require important consideration. The current article reviews the perioperative considerations associated with geriatric hip fractures and takes an evidence-based look at the complex issues involved in managing these patients

PURPOSE: To evaluate what effect the angle of screw-in suture anchor insertion has on fixation stability at the suture-tendon interface. METHODS: Supraspinatus tendons from 7 matched pairs of human cadaveric shoulders were split, yielding 4 tendons per cadaver. An experimental rotator cuff tear was created and repaired, using a 5.0-mm diameter screw-in suture anchor. In a staggered, matched pair arrangement, the angle of anchor insertion was varied between 45 degrees (deadman's angle) and 90 degrees to the articular surface. Each repair underwent cyclic loading, and 2 failure points were defined: the first at 3 mm of repair site gap formation and the second at the point of complete failure. The number of cycles to failure was compared between the 2 groups. RESULTS: The mean number of cycles to 3-mm gap formation for anchors inserted at 90 degrees was 380. This was significantly higher than for repairs made with the 45 degrees angle of anchor insertion (mean, 297 cycles). Complete failure occurred at a significantly greater number of cycles with the 90 degrees anchors (mean, 443 cycles) compared with the 45 degrees anchors (mean, 334 cycles). CONCLUSIONS: Compared with anchors placed at the current standard of the deadman's angle of 45 degrees, suture anchors placed at 90 degrees to the junction of the greater tuberosity and the humeral head articular surface provided improved soft tissue fixation in an experimental rotator cuff model. CLINICAL RELEVANCE: The angle of suture anchor insertion into the greater tuberosity during rotator cuff repair has an effect on the soft tissue fixation at the tendon-suture interface

BACKGROUND: Although the exact mechanism of action has yet to be elucidated, recent animal studies have demonstrated chondroprotective and anti-inflammatory properties of hyaluronic acid viscosupplementation. HYPOTHESIS: Intra-articular hyaluronic acid after microfracture improves the quality of the repair leading to a more hyaline-like repair tissue with better defect fill and adjacent area integration. STUDY DESIGN: Controlled laboratory study. METHODS: Full-thickness cartilage defects were created in the weightbearing area of the medial femoral condyle in 36 female New Zealand White rabbits. The defects were then treated with surgical microfracture. Eighteen rabbits formed the 3-month cohort and the other 18 formed the 6-month cohort. Within each cohort, 6 rabbits were randomly assigned to receive 3 weekly injections of hyaluronic acid (group A), 5 weekly injections (group B), or control injections of normal saline (group C). At 3 and 6 months postmicrofracture, the animals were sacrificed and the operative knee harvested. Repair tissue was assessed blinded- both grossly, using a modified component of the International Cartilage Repair Society (ICRS) Cartilage Repair Assessment scoring scale, and histologically, using the modified O'Driscoll histological cartilage scoring system. Comparisons were made with respect to gross and histologic findings between treatment groups at each time point. Effects of each treatment type were also evaluated longitudinally by comparing the 3-month results with the 6-month results. Statistical analysis was performed using unpaired Student t tests with significance defined as P < .05. RESULTS: At 3 months, gross and histologic evaluation of the repair tissue demonstrated that the 3-injection group had significantly better fill of the defects and more normal appearing, hyaline-like tissue than controls (a mean ICRS score of 1.92 vs 1.26; P < .05 and a mean modified O'Driscoll score of 10.3 vs 7.6; P < .02). Specimens treated with 5 weekly injections were not significantly improved compared with controls. At 6 months, the mean gross appearance and histologic scores between the 3 specimen cohorts were not significantly different. However, examination of the entire operative knee demonstrated a significantly greater extent of degenerative changes (synovial inflammation and osteophyte formation) in the control group than in both hyaluronic acid treatment groups (P < .05). CONCLUSION: Supplementing the microfracture technique with 3 weekly injections of intra-articular hyaluronic acid had a positive effect on the repair tissue that formed within the chondral defect at the early follow-up time point. This improvement was not found for the 3-injection group at 6 months or for the 5-injection group at either time point. Additionally, hyaluronic acid supplementation had a possible chondroprotective and anti-inflammatory effect, limiting the development of degenerative changes within the knee joint. CLINICAL RELEVANCE: The adjunctive use of hyaluronic acid appears to hold promise in the treatment of chondral injuries and warrants further investigation

BACKGROUND: To date, repair of the lacertus in distal biceps tendon ruptures, recommended by some, has not been evaluated. The goal of these biomechanical experiments was to evaluate the degree to which its repair increases the strength of a distal biceps tendon repair. HYPOTHESIS: An intact or repaired lacertus fibrosus will increase the strength of a distal biceps tendon repair. STUDY DESIGN: Controlled laboratory study. METHODS: Four matched pairs of fresh-frozen human cadaveric upper extremities were prepared by isolating the lacertus fibrosus and the distal biceps tendon. The extremity was placed in a custom-built rig with the distal biceps brachii clamped and affixed to a stepper motor assembly. The distal biceps tendon was sharply removed directly from the radial tuberosity and repaired through a bony tunnel in all specimens. One side of each pair was randomized to also receive repair of the lacertus. The specimens were pulled at a constant rate until failure. RESULTS: The mean failure strength, defined as maximal strength to 15 mm of displacement, was higher in specimens with a repaired lacertus (250.2 N vs 158.2 N; P =.012), as was mean maximum strength (256.8 N v. 164.5 N; P =.0058). Mean stiffness was not significantly different (16.36 N/mm vs 13.8 N/mm; P =.58). All specimens failed due to fracture at the bony bridge. CONCLUSION: Repair of the lacertus strengthened distal biceps tendon repair in a controlled laboratory setting. CLINICAL RELEVANCE: Repair of the lacertus fibrosus as an adjunct to distal biceps tendon repair strengthens the repair in the laboratory setting. Clinical testing is needed to verify that this increased strength improves clinical results. Surgeons should be cautioned to protect the underlying neurovascular structures during repair of the lacertus fibrosus and to avoid an overly tight repair

BACKGROUND: The Bio-Transfix pin is a biodegradable device used for femoral tunnel anterior cruciate ligament (ACL) graft fixation. Recent clinical studies have suggested the possibility of the pin's postoperative failure. METHODS: This investigation evaluates the initial strength of several Bio-Transfix pin ACL fixations in a simulated femoral tunnel model. The forces generated by five surgeons during simulated ACL graft tensioning were also measured. RESULTS: Average strengths of the pins ranged from 1075 to 2160 N for 10 and 8 mm tunnels, respectively, whereas the maximum surgeon-generated forces were 535 N. CONCLUSIONS: These results imply that initial fracture of the pin itself is unlikely; however, failure of the supporting bone or a decrease in pin strength due to biodegradation could account for early loss of the fixation

The strengths of 3 hip spacer constructs--Steinmann pins, a short intramedullary nail (both cement-incorporated), and a Charnley prosthesis--were determined and compared with the strength of a commercially available hip spacer. The hip prosthesis construct was more than twice as strong as the other 2 constructs and was equivalent in strength to the commercial spacer. For spacer applications in which limited weight-bearing is anticipated, the hip prosthesis construct appears more efficacious, but its pros and cons should be compared with those of the commercial product

Locked plate technology has evolved in an effort to overcome the limitations associated with conventional plating methods, primarily for improving fixation in osteopenic bone. The development of screw torque and plate-bone interface friction is unnecessary with locked plate designs, significantly decreasing the amount of soft tissue dissection required for implantation, preserving the periosteal blood supply, and facilitating the use of minimally invasive percutaneous bridging fixation techniques. The locked plate is a fixed-angle device because angular motion does not occur at the plate screw interface. The use of locked plate technology allows the orthopaedic surgeon to manage fractures with indirect reduction techniques while providing stable fracture fixation. The secure 'feel' of locked plates, ease of application, and the low incidence of complications noted in early clinical reports have contributed to the proliferation of this technology. Along with reports of clinical successes, as the use of fixed angle/locked plates has increased, clinical failures are being noticed. This review will focus on the biomechanics of locked plate technology, appropriate indications for its use, laboratory and clinical comparisons to conventional plating techniques, and potential mechanisms of locked plate failure that have been observed