Richard W. Kang

Tibiofemoral Contact Mechanics after Serial Medial Meniscectomies in the Human Cadaveric Knee

Background There is no consensus regarding the extent of meniscectomy leading to deleterious effects on tibiofemoral contact mechanics. Hypothesis The meniscus aids in optimizing tibiofemoral contact mechanics, increasing contact area, and decreasing contact stress. Study Design Controlled laboratory study. Methods Twelve fresh-frozen human cadaveric knees each underwent 15 separate testing conditions—5 serial 20-mm posterior medial meniscectomy conditions (intact, 50% radial width, 75% radial width, segmental, and total meniscectomy) at 3 flexion angles (0°, 30°, and 60°)—under an 1800-N axial load. Tekscan sensors were used to measure total force and medial force, contact area, mean contact stress, and peak contact stress. Results All posterior medial meniscectomy conditions resulted in significantly decreased contact areas and increased mean and peak contact stresses compared with the intact state (P < .05). The changes in contact mechanics after segmental and total posterior medial meniscectomies were not statistically different (P > .05). Incremental changes in contact area and mean contact stress increased as more peripheral portions of the medial meniscus were removed, whereas peak contact stresses exhibited similar incremental changes throughout all meniscectomy conditions. Conclusions The meniscus is a crucial load-bearing structure, optimizing contact area and minimizing contact stress. Loss of hoop tension (ie, segmental meniscectomy) is equivalent to total meniscectomy in load-bearing terms. The peripheral portion of the medial meniscus provides a greater contribution to increasing contact areas and decreasing mean contact stresses than does the central portion, whereas peak contact stresses increase proportionally to the amount of meniscus removed. Clinical Relevance Because the degree of meniscectomy leading to clinically significant outcomes is unknown, a prudent strategy is to preserve the greatest amount of meniscus possible.

Prospective Evaluation of Prolonged Fresh Osteochondral Allograft Transplantation of the Femoral Condyle Minimum 2-Year Follow-Up

Background Focal articular cartilage lesions of the knee in young patients present a therapeutic challenge. Little information is available pertaining to the results after implantation of prolonged fresh grafts. Hypothesis Prolonged fresh osteochondral allografts present a viable option for treating large full-thickness articular cartilage lesions. Study Design Case series; Level of evidence, 4. Methods This study presents the results of 25 consecutive patients who underwent prolonged fresh osteochondral allograft transplantation for defects in the femoral condyle. The average patient age was 35 years (range, 17-49 years). The average length of follow-up was 35 months (range, 24-67 months). Prospective data were collected using several subjective scoring systems, as well as objective and radiographic assessments. Results Statistically significant improvements (P < .05) were seen for the Lysholm (39 to 67), International Knee Documentation Committee scores (29 to 58), all 5 components of the Knee injury and Osteoarthritis Outcome Score (Pain, 43 to 73; Other Disease-Specific Symptoms, 46 to 64; Activities of Daily Living Function, 56 to 83; Sport and Recreation Function, 18 to 46; Knee-Related Quality of Life, 22 to 50), and the Short Form-12 physical component score (36 to 40). Overall, patients reported 84% (range, 25% to 100%) satisfaction with their results and believed that the knee functioned at 79% (range, 35% to 100%) of their unaffected knee. Radiographically, 22 of the grafts (88%) were incorporated into host bone. Conclusion Fresh osteochondral allograft transplantation is an acceptable intermediate procedure for treatment of localized osteochondral defects of the femur. At 2-year follow-up, it is well incorporated and offered consistent improvements in pain and function. Clinical Relevance Prolonged fresh allograft transplantation is a safe and effective technique for addressing symptomatic osteoarticular lesions in the knees of young patients.

Long-Term Effects of Bupivacaine on Cartilage in a Rabbit Shoulder Model

Background Previous investigations have reported on the chondrotoxicity of bupivacaine in short-term in vivo and in vitro models. This study was designed to provide additional information on the long-term effects of bupivacaine infusion on articular cartilage in an established rabbit shoulder model. Hypothesis Infusion of bupivacaine into the rabbit shoulder will have long-term deleterious effects on articular cartilage. Study Design Controlled laboratory study. Methods Thirty-six rabbits were randomized into 3 groups and were infused over 48 hours with saline (S), bupivacaine alone (B), or bupivacaine with epinephrine (B+E) into the glenohumeral joint. Animals were sacrificed after 3 months, and tissue samples were analyzed with live/dead cell assay, proteoglycan (PG) synthesis and content assays, and conventional histological evaluation. Results No macroscopic or radiographic changes were detected in the infused shoulders. Sulfate uptake of infused shoulders relative to controls was elevated to 112% ± 39% (S), 166% ± 67% (B), and 210% ± 127% (B+E). Statistical analysis of PG content demonstrated significantly increased levels in bupivacaine groups compared with saline. There were no significant differences among groups in cell count, percentage of living cells, or histological grade. Conclusions No permanent impairment of cartilage function was detected 3 months after intra-articular infusion of bupivacaine. Cartilage metabolism was increased, indicating a possible reparative response. This suggests that, at least in the model used, articular cartilage has the ability to recover from the chondrotoxic effects of bupivacaine infusion. Before extrapolating these results to human cartilage, other factors including underlying cartilage injury or disease, decreased chondrocyte density, and increased bupivacaine dosing need to be taken into account. Clinical Relevance Bupivacaine toxicity has recently been implicated in the development of chondrolysis after arthroscopic shoulder procedures, but these findings suggest that additional noxious stimuli might be required before permanent damage ensues.

Biceps tendinitis in chronic rotator cuff tears : A histologic perspective

Patients with chronic rotator cuff tears frequently have anterior shoulder pain attributed to the long head of the biceps brachii (LHBB) tendon. In this study, tenodesis or tenotomy samples and cadaveric controls were assessed by use of immunohistochemical and histologic methods to quantify inflammation, vascularity, and neuronal plasticity. Patients had moderate pain and positive results on at least 1 clinical test of shoulder function. The number of axons in the distal LHBB was significantly less in patients with biceps tendinitis. Calcitonin gene-related peptide and substance P immunostaining was predominantly within nerve roots and blood vessels. A moderate correlation (R = 0.5) was identified between LHBB vascularity and pain scores. On the basis of these results, we conclude that, in the context of rotator cuff disease, the etiology of anterior shoulder pain with macroscopic changes in the biceps tendon is related to the complex interaction of the tendon and surrounding soft tissues, rather than a single entity.

Complications Associated With Anterior Shoulder Instability Repair

Anterior shoulder instability is a common orthopaedic problem, and the surgical treatment, both open and arthroscopic, has been shown to effectively restore stability and prevent recurrence. However, despite success with these surgical techniques, there are several clinically relevant complications associated with both open and arthroscopic techniques for anterior shoulder stabilization. These complications can be subdivided into preoperative, intraoperative, and postoperative and include entities such as nerve injury, chondrolysis, incomplete treatment of associated lesions, and subscapularis dysfunction. When they occur, complications may significantly impact patient outcomes and function. Therefore, surgeon awareness and identification of the factors associated with these complications may help prevent occurrence. Although failure of instability repair can be classified as a complication of surgery, it requires an entirely separate discussion and is therefore not addressed in this article. Because most of the previously published studies on anterior shoulder instability have emphasized surgical technique and clinical outcomes, the purpose of this article is to define the complications associated with anterior instability repair and provide recommendations on techniques that may be used to help avoid them.

Allograft Meniscus Transplantation

Menisci function to manage load transmission, provide secondary mechanical stability as well as nutrition, and lubricate the joint. Meniscus transplantation techniques continue to evolve and include: free soft tissue allograft implantation; separate anterior and posterior bone plugs; and bone bridges including key hole, trough, dovetail, and bridge-in-slot variations. The senior author’s preference is for the bridge-in-slot technique for lateral and medial menisci, owing to its simplicity and secure bony fixation, flexibility in allowing concomitant procedures as osteotomy and ligament reconstruction, and the ability to maintain the native anterior and posterior meniscal horn attachments. Meniscal allograft transplantation yields fair to excellent results in almost 85% of patients. Patients demonstrate significant decrease in pain, as well as an increase in activity. Long-term success is encouraging in well-selected patients but is unknown whether transplantation is protective against the progression of degenerative changes.

Effect of Impaction Sequence on Osteochondral Graft Damage: The Role of Repeated and Varying Loads

Background Osteochondral autografts and allografts require mechanical force for proper graft placement into the defect site; however, impaction compromises the tissue. This study aimed to determine the effect of impaction force and number of hits to seat the graft on cartilage integrity. Hypothesis Under constant impulse conditions, higher impaction load magnitudes are more detrimental to cell viability, matrix integrity, and collagen network organization and will result in proteoglycan loss and nitric oxide release. Study Design Controlled laboratory study. Methods Osteochondral explants, harvested from fresh bovine trochleae, were exposed to a series of consistent impact loads delivered by a pneumatically driven device. Each plug received the same overall impulse of 7 Ns, reflecting the mean of 23 clinically inserted plugs. Impaction loads of 37.5 N, 75 N, 150 N, and 300 N were matched with 74, 37, 21, and 11 hits, respectively. After impaction, the plugs were harvested, and cartilage was analyzed for cell viability, histology by safranin-O and picrosirius red staining, and release of sulfated glycosaminoglycans (GAGs) and nitric oxide. Data were compared with nonimpacted controls. Results Impacted plugs had significantly lower cell viability than nonimpacted plugs. A dose-response relationship in loss of cell viability with respect to load magnitude was seen immediately and after 4 days but lost after 8 days. Histological analysis revealed intact cartilage surface in all samples (loaded or control), with loaded samples showing alterations in birefringence. While the sulfated GAG release was similar across varying impaction loads, release of nitric oxide increased with increasing impaction magnitudes and time. Conclusion Impaction loading parameters have a direct effect on the time course of the viability of the cartilage in the graft tissue. Clinical Relevance Optimal loading parameters for surgical impaction of osteochondral grafts are those with lower load magnitudes and a greater number of hits to ensure proper fit.

A Randomized, Prospective, Double-Blind Study to Investigate the Effectiveness of Adding DepoMedrol to a Local Anesthetic Injection in Postmeniscectomy Patients With Osteoarthritis of the Knee

Background Patients with osteoarthritis of the knee are at risk for poorer outcomes after arthroscopic meniscectomy. Intra-articular corticosteroid injections have been shown to be efficacious both in patients with osteoarthritis and postarthroscopy patients. Hypothesis A postoperative, intra-articular methylprednisolone and lidocaine injection in patients with chondromalacia undergoing meniscectomy will improve patient-rated pain and function compared with control patients. Study Design Randomized, controlled trial; Level of evidence, 1. Methods A total of 58 patients (59 knees) were randomized in a double-blinded fashion to receive either saline plus lidocaine (saline) or methylprednisolone plus lidocaine (steroid) after arthroscopic meniscectomy in which chondromalacia (modified Outerbridge grade 2 or higher) was confirmed. Preoperatively and at follow-up—6 weeks and 6, 9, and 12 months—patients underwent an examination and completed a subjective functioning survey. Scores were calculated using several validated scoring systems including the Lysholm, International Knee Documentation Committee (IKDC), and Short Form–12 (SF-12). Results No statistically significant differences were observed between the saline (n = 30) and steroid (n = 29) groups in their demographics and preoperative scores. At 6 weeks, the steroid group had higher scores than the saline group on multiple scales, including the IKDC. No differences in outcome scores existed at later time points. At 12 months, 86% of the steroid and 69% of the saline group were completely or mostly satisfied with the procedure (P = .01). In the saline group, 4 patients required reinjection and 2 underwent joint replacements within 12 months, while the steroid group had 3 reinjections and 2 meniscus transplants. Conclusion The addition of a postoperative corticosteroid injection resulted in improved pain and function at an early time point; however, it provided no lasting difference compared with only local anesthetic injection.

Emerging ideas: Novel 3-D quantification and classification of cam lesions in patients with femoroacetabular impingement.

BackgroundFemoroacetabular impingement (FAI) can lead to labral injury, osseous changes, and even osteoarthritis. The literature contains inconsistent definitions of the alpha angle and other nonthree-dimensional (3-D) radiographic measures. We present a novel approach to quantifying cam lesions in 3-D terms. Our method also can be used to develop a classification system that describes the exact location and size of cam lesions.Questions/HypothesesWe asked whether automated quantification of CAM lesions based on CT data is a reasonable way to detect CAM lesions and whether they may be classified based on location.Method of StudyWe developed a method to quantify femoral head cam lesions using 3-D modeling of CT scans. By segmenting raw DICOM data, we can determine the distance from the cam lesion’s surface points to the centroid of the femoral head to quantify the mean bump height, volume, and location. The resulting 3-D femoral and acetabular models will be analyzed with custom software. We then will quantify the cam lesion with 3-D parameters using a modified zoning method. The mean bump height, volume, and location on the clock face, and relative zoning will be calculated. Zonal differences will be statistically analyzed. To assess the ability of this method to predict arthroscopic findings, we will obtain preoperative CT scans for 25 patients who undergo hip arthroscopy for FAI. We will compare measurements with the method with our measurements from arthroscopy. The clinical implications of our method’s measurements then will be reviewed and refined for future prospective studies.SignificanceWe present a novel approach that can quantify a cam lesion’s location and size. This method will be used to provide guidelines for the exact amount of bony resection needed from a specific location of the proximal femur. There is also potential to develop software for ease of use so this method can be more widely applied.

What's new in the treatment of focal chondral defects of the knee?

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