Normal curvature of glenoid surface can be restored when performing an inlay osteochondral allograft: an anatomic computed tomographic comparison.

PURPOSE: The purpose of this study was to quantitatively measure the morphology of the glenoid and to assess feasibility of using the medial tibial plateau surface as a donor for osteoarticular allograft reconstruction of the glenoid. METHODS: Using computed tomography (CT), 10 tibias and 10 scapular models from our database (5 males and 5 females in each group) were randomly selected. Commercial software (Mimics, Materialize, Inc., Plymouth, MI) was used to extract the bone contours from the CT images and to reconstruct the 3-dimensional (3D) geometry of the scapula and tibia. By utilizing the software Creo Elements/Pro 5.0 (Parametric Technology Corp., Needham, MA), mean length and width of both the glenoid and medial tibial plateau were calculated. Radius of curvature was then measured in each 3D CT model at three intermediate segment points that were established within the length line at 25, 50, and 75 percent from superior to inferior in the glenoid and from posterior to anterior in the medial tibial plateau. Statistical analysis was performed and determined to be significant for P < 0.05. RESULTS: The mean (± SD) radius of curvature values at the established 25, 50, and 75 percent segments of the glenoid were 47.4 ± 17.5 mm, 51.2 ± 12.4 mm, and 45.9 ± 17.0 mm, respectively. For the medial tibial plateau, the radius of curvature at 25, 50, and 75 percent were 43.5 ± 9.7 mm, 37.4 ± 14.3 mm and 52.3 ± 21.5 mm, respectively. Values of the glenoid length were 34.0 ± 2.9 mm, and width values were 24.4 ± 2.3 mm. For the medial tibial plateau, the length was 42.6 ± 2.7 mm, and the width was 23.3 ± 4.3 mm. There was no statistical difference in the radius of curvature and dimensional surface area between the glenoid and medial tibial plateau surfaces. CONCLUSION: The 3D CT-based anatomic study found that there is a statistically similar relationship in the radius of curvature of the glenoid and the medial tibial plateau surface. This concept may allow the medial tibial plateau to be used as a donor for osteoarticular allograft reconstruction of the glenoid, especially in young patients where previous studies have demonstrated that the success rate in shoulder replacements is not as good as in older patients.

Acromioclavicular and coracoclavicular PDS augmentation for complete AC joint dislocation showed insufficient properties in a cadaver model.

PURPOSE: Optimal surgical treatment of high-grade acromioclavicular joint dislocations is still controversially discussed. The purpose of the present controlled laboratory study was to evaluate whether a polydioxansulfate (PDS(®)) cord augmentation with separate reconstruction of the coracoclavicular (CC) ligaments and the acromioclavicular (AC) complex provides sufficient vertical stability in a biomechanical cadaver model. METHODS: Twenty-four shoulders of fresh-frozen cadaveric specimen were tested. Cyclic loading and load to failure protocol was performed in vertical direction on 12 native AC joints and repeated after reconstruction. The reconstruction of the coracoclavicular ligament was performed using two CC PDS cerclages and an additional AC PDS cerclage. RESULTS: In static load testing for vertical force, the native AC joint complex measured 590.1 N (±95.8 N), elongation 13.4 mm (±2.1 mm) and stiffness 48.7 N/mm (±12.0 N/mm). The mean maximum load to failure in the reconstructed joints was 569.9 N (±97.9 N), elongation 18.8 mm (±4.7 mm) and stiffness 37.9 N/mm (±8.0 N/mm). During dynamic testing of the reconstructed AC joints, all specimens reached the critical elongation of 12.0 mm, defined as clinical failure between 200 and 300 N. The mean amount of repetitions at clinical failure was 305. A plastic deformation of the reconstructed specimens throughout cyclic loading could not be detected. CONCLUSION: The AC joint reconstruction with acromioclavicular and coracoclavicular PDS cord cerclages did not provide the aspired vertical stability in a cadaver model. LEVEL OF EVIDENCE: Basic Science Study.

A Tensionable Suture-based Cerclage Is an Alternative to Stainless Steel Cerclage Fixation for Stabilization of a Humeral Osteotomy During Shoulder Arthroplasty.

INTRODUCTION: Fixation of periprosthetic humeral fractures is most commonly obtained with steel-based wires or cables; however, disadvantages with these constructs are numerous. Suture-based cerclages offer the advantage of easy handling, less radiographic interference, and risk of metallosis, as well as decreased risk of cutting into the soft humeral bone. Therefore, the purpose of this study was to compare a suture-based cerclage to a stainless steel wire cerclage (SSWC) for stabilization of the humerus during shoulder arthroplasty. METHODS: In part I of the study, SSWC fixation was compared with single-looped tape cerclage and a double-looped tape cerclage (DLTC) fixation. In part II, a subsidence test was performed on 12 cadaveric humeri. After an osteotomy, the humeri were secured with either a SSWC or DLTC. Subsequently, a metal wedge was introduced into the humerus to simulate the stem of a shoulder arthroplasty. RESULTS: In part I, load to 2-mm displacement was significantly higher for the DLTC construct compared with the SSWC construct (2,401 ± 483 N versus 750 ± 33 N; P < 0.0001). Load to failure was 935 ± 143 N with the SSWC, 1,737 ± 113 N with the single-looped tape cerclage, and 4,360 ± 463 N with the DLTC constructs, and all differences were statistically significant (P < 0.05). In part II, load at 20-mm subsidence was higher for the DLTC (320 ± 274 N) compared with the SSWC (247 ± 137 N), but no significant difference was observed (P > 0.05). However, gap displacement at 20 mm subsidence was significantly lower with the DLTC construct (0.33 ± 0.31 mm versus 0.77 ± 0.23 mm; P = 0.009). Load to failure was higher with the DLTC construct compared with the SSWC construct (4,447 ± 2,325 N versus 1,880 ± 1,089 N; P = 0.032), but the final gap displacement did not differ significantly (DLTC 5.23 ± 6.63 mm versus SSWC 6.03 ± 8.82 mm; P > 0.05). DISCUSSION: A DLTC has higher load to failure and trends toward lower gap displacement compared with a SSWC. The DLTC construct may therefore be a viable alternative for fixation of periprosthetic fractures or osteotomies of the humeral shaft during shoulder arthroplasty.

Broken femoral cross pin after hamstring anterior cruciate ligament reconstruction: case report.

Two years after a quadrupled hamstring anterior cruciate ligament reconstruction using polylactic acid cross pin femoral fixation, a 32-year-old woman presented with symptoms of knee catching, locking, and stiffness. Diagnostic arthroscopy revealed a loose body in the anterior compartment of the knee which was determined to be part of the polylactic acid femoral fixation pin. The graft was intact and well fixed. After simple arthroscopic removal, the patient returned to full activities and resumed normal function postoperatively. We speculate that the fixation pins may have entered the notch and later degraded or fractured. Using axial magnetic resonance images, we provide preliminary data suggesting that pins angled posterior to the epicondylar axis may violate the notch. If pins are to be placed posterior to the epicondylar axis, maximum pin length can be estimated by the formula: 0.4 x the interepicondylar distance.

Effects of alendronate on particle-induced osteolysis in a rat model.

BACKGROUND: Particle-induced osteolysis is currently a major problem affecting the long-term survivorship of total joint replacements. Alendronate is a third-generation bisphosphonate that blocks osteoclastic bone resorption. The objective of this study was to determine whether alendronate could prevent particle-induced osteolysis or restore (reverse) bone loss in established osteolysis. METHODS: A rat model of particle-induced osteolysis was used. A specially designed polyethylene implant was placed in the proximal part of the right tibia of seventy-two animals. Following four weeks of healing, the animals were randomized into control groups, a prevention group, or a treatment group. In the prevention group, animals received intra-articular injections of high-density polyethylene particles (mean size, 2 m; all <10 m) at four, six, and eight weeks postoperatively. Alendronate (0.01 mg/kg/day) was administered concomitantly through an implantable pump from the fourth week through the tenth week. In the treatment group, animals were also exposed to polyethylene particles at four, six, and eight weeks, to establish bone loss, but they received alendronate subsequently, from the tenth week through the sixteenth week, to treat the bone loss. Positive (particle-only) and negative (saline-solution-only) control groups were assessed as well. Tissues were harvested at ten weeks in the prevention group and at sixteen weeks in the treatment group. Histological analyses and histomorphometric determinations of the periprosthetic bone volume were carried out. RESULTS: Histological examination showed a rim of new bone (neocortex) around the implant in the untreated and saline-solution-treated control animals (no polyethylene particles). Treatment with saline solution (no polyethylene particles) did not affect periprosthetic bone. Animals exposed to polyethylene particles had bone loss. In those that received alendronate, the bone loss was either prevented or reversed, and the quantity of neocortical and trabecular bone was increased compared with that of the controls. Alendronate effectively preserved periprosthetic bone in both the prevention and treatment groups. In the prevention arm, the mean periprosthetic bone volume of the neocortex and the surrounding trabecular bone, as determined with histomorphometry, was 21.5% +/- 6.5% in the saline-solution-treated controls (no particles), 13.1% +/- 5.9% in the particle-treated animals, and 32.6% +/- 6.4% in the alendronate-treated animals (p < 0.001). In the treatment arm, the mean periprosthetic bone volume was 27.2% +/- 5.6% in the saline-solution-treated controls, 17.7% +/- 6.2% in the particle-treated animals, and 30.2% +/- 5.9% in the alendronate-treated animals (p = 0.002). CONCLUSIONS: In our model, the intra-articular injection of polyethylene particles caused substantial bone loss around a loaded implant. Alendronate effectively prevented and treated the particle-induced periprosthetic bone loss.

Arthroscopic repair of SLAP lesions with a bioknotless suture anchor.

The diagnosis and treatment of SLAP tears have improved with the development of arthroscopic shoulder surgery techniques. With types 2 and 4 tears, the goal is to restore stability to the labrum and biceps anchor and achieve healing to the glenoid. Suture repair with anchors is currently the repair technique of choice. The purpose of this article is to report a fast and simple method for arthroscopic SLAP repair that uses knotless suture anchors and obviates complex suture management and arthroscopic knot tying.