Faculty Bibliography

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: 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

BACKGROUND: Tumorigenic breast cancer cells that express high levels of CD44 and low or undetectable levels of CD24 (CD44(>)/CD24(>/low)) may be resistant to chemotherapy and therefore responsible for cancer relapse. These tumorigenic cancer cells can be isolated from breast cancer biopsies and propagated as mammospheres in vitro. In this study, we aimed to test directly in human breast cancers the effect of conventional chemotherapy or lapatinib (an epidermal growth factor receptor [EGFR]/HER2 pathway inhibitor) on this tumorigenic CD44(>) and CD24(>/low) cell population. METHODS: Paired breast cancer core biopsies were obtained from patients with primary breast cancer before and after 12 weeks of treatment with neoadjuvant chemotherapy (n = 31) or, for patients with HER2-positive tumors, before and after 6 weeks of treatment with the EGFR/HER2 inhibitor lapatinib (n = 21). Single-cell suspensions established from these biopsies were stained with antibodies against CD24, CD44, and lineage markers and analyzed by flow cytometry. The potential of cells from biopsy samples taken before and after treatment to form mammospheres in culture was compared. All statistical tests were two-sided. RESULTS: Chemotherapy treatment increased the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 12 weeks, 4.7%, 95% confidence interval [CI] = 3.5% to 5.9%, vs 13.6%, 95% CI = 10.9% to 16.3%; P < .001) and increased mammosphere formation efficiency (MSFE) (mean at baseline vs 12 weeks, 13.3%, 95% CI = 6.0% to 20.6%, vs 53.2%, 95% CI = 42.4% to 64.0%; P < .001). Conversely, lapatinib treatment of patients with HER2-positive tumors led to a non-statistically significant decrease in the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 6 weeks, 10.0%, 95% CI = 7.2% to 12.8%, vs 7.5%, 95% CI = 4.1% to 10.9%) and a statistically non-significant decrease in MSFE (mean at baseline vs 6 weeks, 16.1%, 95% CI = 8.7% to 23.5%, vs 10.8%, 95% CI = 4.0% to 17.6%). CONCLUSION: These studies provide clinical evidence for a subpopulation of chemotherapy-resistant breast cancer-initiating cells. Lapatinib did not lead to an increase in these tumorigenic cells, and, in combination with conventional therapy, specific pathway inhibitors may provide a therapeutic strategy for eliminating these cells to decrease recurrence and improve long-term survival.

Rugby football continues to grow in popularity internation- ally and within the United States. In 1995, rugby union, one form of rugby, turned from amateur to professional through- out Europe, increasing the potential for monetary reward, which, in turn, secondary to higher levels of play, increased the risk of injury. With this increased higher interest and the increasing number of inexperienced and professional players in the U.S., there is a need for a comprehensive analysis of professional rugby union injury in the American literature and increased awareness of rugby injuries, in general, for all levels of players. This paper provides an in-depth analysis of professional rugby union injuries that will assist ortho- paedic surgeons treating these injuries in the U.S. The data described highlights the potential impact of rugby injury in the U.S. and provides an overview of the international data to serve as the basis for future American studies. An additional goal of this review is to stimulate discussion regarding the necessity of implementing additional safety precautions for this high-risk sport. Finally, this analysis highlights the in- consistencies and discrepancies of the literature with respect to rugby union injury and the variability and weak interstudy reproducibility of current rugby injury data

Purpose: There are many options for arthroscopic knots including the type of knot and suture material used. The current investigation evaluated knot properties using 3 high-strength suture materials tied in 5 common arthroscopic knot configurations. Methods: Four arthroscopic sliding knots including the Roeder, Weston, SMC, and Tennessee Slider and an arthroscopic nonsliding Surgeon's knot were evaluated. Each knot was tied with each of 3 No. 2 polyblended suture types (Fiberwire [Arthrex, Naples, FL], Ultrabraid [Smith & Nephew, Andover, MA], and Orthocord [Mitek, Raynham, MA]). Each configuration was tied 8 times, for a total of 120 samples. Loop security and knot security were then evaluated by using a previously described protocol comparing the different knot types and suture material. Results: With respect to loop security, Orthocord performed better than the other tested suture materials, producing on average smaller knot loops. For the nonsliding Surgeon's knot, there was no difference in loop security observed between suture types. For the Roeder knot, Fiberwire had superior knot security compared with Ultrabraid and Orthocord (P < .001). For the Weston knot, Ultrabraid showed superior knot security compared with Orthocord (P < .02). Knot security for the Tenessee slider knot was better for both Fiberwire and Ultrabraid compared with Orthocord (P < .001, respectively). Similar results were seen with the SMC knot, with Fiberwire and Ultrabraid outperforming Orthocord (P < .001, respectively). The nonsliding Surgeon's knot had significantly lower mean loads to failure compared with arthroscopic sliding knots for each tested suture material (P < .02 for all comparisons). Conclusions: Loop security and knot security varied depending on the type of knot tied and suture material used. Arthroscopic sliding knots performed better than the nonsliding Surgeon's knot. Clinical Relevance: Surgeons should try to use sliding knots instead of Surgeon's knots when using polyblend suture material. Differences between the brands in this suture category will change the characteristics of the knots thrown and may ultimately affect tissue fixation

OBJECTIVE: To determine whether positioning of the tibia affects the degree of tibial external rotation seen during a dial test in the posterior cruciate ligament (PCL)-posterolateral corner (PLC)-deficient knee. DESIGN: Laboratory investigation. SETTING: Biomechanics laboratory. Hypothesis: An anterior force applied to the tibia in the combined PCL-PLC-deficient knee will yield increased tibial external rotation during a dial test. METHODS: The degree of tibial external rotation was measured with 5 Nm of external rotation torque applied to the tibia at both 30 degrees and 90 degrees of knee flexion. Before the torque was applied, an anterior force, a posterior force, or neutral (normal, reduced control) force was applied to the tibia. External rotation measurements were repeated after sequential sectioning of the PCL, the posterolateral structures and the fibular collateral ligament (FCL). RESULTS: Baseline testing of the intact specimens demonstrated a mean external rotation of 18.6 degrees with the knee flexed to 30 degrees (range 16.1-21.0 degrees ), and a mean external rotation of 17.3 degrees with the knee flexed to 90 degrees (range 13.8-20.0 degrees ). Sequential sectioning of the PCL, popliteus and popliteofibular ligament, and the FCL led to a significant increase in tibial external rotation compared with the intact knee for all testing scenarios. After sectioning of the popliteus and popliteofibular ligament, the application of an anterior force during testing led to a mean tibial external rotation that was 5 degrees greater than during testing in the neutral position and 7.5 degrees greater than during testing with a posterior force. In the PCL, popliteus/popliteofibular ligament and FCL-deficient knee, external rotation was 9 degrees and 12 degrees greater with the application of an anterior force during testing compared with neutral positioning and the application of a posterior force, respectively. CONCLUSION: An anterior force applied to the tibia during the dial test in a combined PCL-PLC-injured knee increased the overall amount of observed tibial external rotation during the dial test. The anterior force reduced the posterior tibial subluxation associated with PCL injury, which is analogous to what is observed when the dial test is performed with the patient in the prone position. Reducing the tibia with either an anterior force when the patient is supine or performing the dial test with the patient in the prone position increases the ability of an examiner to detect a concomitant PLC injury in the setting of a PCL-deficient knee

PURPOSE: To retrospectively review the clinical outcome and incidence of post-operative complications after open end-to-end repair of acute Achilles tendon ruptures. METHODS: Seventy consecutive patients (74 open Achilles tendon repairs) operated on between 1989 and 2002 were identified for inclusion in this investigation. The medical records were reviewed and patients were contacted for a follow up interview in order to survey their post-operative function. Outcome scores were calculated based on the Boyden outcome and AOFAS ankle-hindfoot scoring systems. Post-operative complications were documented during the chart review and follow up interview, including an additional nine patients (nine repairs), who were not included in the clinical evaluation portion of the study. RESULTS: Fifty-two patients (54 repairs) were successfully contacted and completed the follow up interview. Within this cohort there were 44 males and 8 females with a mean age of 41 years. Achilles tendon rupture in this population was attributable to participation in athletic activity in 87% of cases. At a mean post-operative follow up of 45 months, 96% of cases achieved an overall Boyden outcome score of good to excellent. The mean AOFAS ankle-hindfoot score was 96, with 74% of cases scoring greater than 90. Forty-two cases (78%) reported no pain and 40 cases (74%) reported no activity limitations. Fourteen post-operative complications were identified after 83 open Achilles tendon repairs, resulting in an institutional complication rate of 16.8%. The complications included four superficial wound infections, five deep wound infections requiring irrigation and debridement, one heel ulcer secondary to post-operative boot wear, three partial Achilles tendon re-ruptures, and one complete Achilles tendon re-rupture. CONCLUSION: Our results demonstrate that open end-to-end repair of acute Achilles tendon ruptures provides long-term functional outcomes with consistent good to excellent results. However, this high clinical success rate was associated with a relatively high incidence of post-operative complications. With careful attention to the surgical wound and patient adherence to post-operative rehabilitation protocols, operative repair of acute Achilles tendon ruptures is a reliable treatment for active patients

The heightened intensity of training and competition among young athletes places them at increased risk for both acute and chronic injuries. Prompt recognition and treatment of such injuries are critical to prevent long-term functional disability and deformity. These injuries occur in patterns unique to the skeletally immature athlete, given their developing epiphyses and ossification centers and supporting ligamentous structures. Children and adolescents who participate in recreational and organized sports are particularly susceptible to a broad spectrum of lower extremity injuries involving both the osseous and soft-tissue structures. Fundamental knowledge of the pathophysiology of injury helps the clinician in determining management. Early recognition of acute traumatic injuries, along with preventive regimens and knowledge of both nonsurgical and surgical treatment protocols, has helped to restore and maintain normal lower extremity function in the skeletally immature athlete

Sliding knots are commonly used in arthroscopic surgery and can be problematic in terms of strength and loop security. A new sliding knot for arthroscopic surgery, a modified racking hitch (MRH) knot, is described. The knot is essentially a modified cow's hitch knot that includes two self-locking loops. By tensioning the loop strands, a snug knot is created without backward sliding and provides excellent knot and loop security. In laboratory testing, the MRH knot provided comparable strength and security to other sliding knots. Experience gained from approximately 5 years of clinical use has added to the promise of the useful application of the MRH knot in arthroscopy