Medial-Sided Ligamentous Injuries of the Athlete's Knee: Evaluation and Management.

The superficial medial collateral ligament (sMCL) is the most commonly injured ligamentous structure in the knee. The other medial knee stabilizers include the deep medial collateral ligament, the posterior oblique ligament, and the medial meniscus. Medial collateral ligament injuries frequently occur in young athletes. As a result of the good healing capacity of the sMCL, the majority of acute medial-sided knee injuries can be treated nonoperatively with good outcomes. However, missed concomitant injuries can lead to residual laxity and instability of the knee when treated conservatively. When surgical management is warranted, numerous techniques exist, including repair, augmentation, and reconstruction. Recent anatomic and biomechanical studies defining the attachment sites and functional roles of the individual medial knee structures have led to advancements in diagnosis, treatment, and rehabilitation. These studies have allowed for the development of an anatomic reconstruction technique that restores the native stability and load-sharing relationships among the medial knee structures. The purpose of this narrative review is to summarize the recent updates in the anatomy, biomechanics, evaluation, and treatment of ligamentous injuries on the medial side of the athlete's knee.

Biomechanical Comparison of Adjustable-Loop Femoral Cortical Suspension Devices for Soft Tissue ACL Reconstruction.

Background: Several new adjustable-loop devices (ALDs) for anterior cruciate ligament reconstruction (ACLR) have not been tested in vitro. Purpose: To compare the biomechanical performances of 5 ALDs under a high cyclic load and forces representative of the return-to-play conditions seen in the recovering athlete. Study Design: Controlled laboratory study. Methods: A total of 10 devices for each of 5 chosen ALDs (UltraButton [Smith & Nephew], RigidLoop [DePuy Mitek], ProCinch [Stryker], TightRope [Arthrex], and ToggleLoc [Biomet]) were tested in a device-only model. The devices were secured to a servohydraulic test machine and preconditioned from 10 to 75 N at a rate of 0.5 Hz for 20 cycles. They were then subjected to high cyclic forces (100-500 N for 4000 cycles) and subsequently pulled to failure at 50 mm/min. The preconditioning displacement, permanent deformation, cumulative peak displacement, stiffness coefficient, and load to failure data were collected. Results: The UltraButton displayed the greatest preconditioning displacement (0.22 ± 0.20 mm), followed by the RigidLoop (0.11 ± 0.03 mm), ProCinch (0.07 ± 0.04 mm), TightRope (0.07 ± 0.02 mm), and ToggleLoc (0.02 ± 0.03 mm). The TightRope displayed the greatest permanent deformation (3.19 ± 1.03 mm) followed by the UltraButton (2.14 ± 0.92 mm), ToggleLoc (2.02 ± 1.09 mm), RigidLoop (1.67 ± 0.1 mm), and ProCinch (1.38 ± 0.18 mm). The TightRope displayed the greatest cumulative peak displacement (3.69 ± 1.03 mm) followed by the UltraButton (2.46 ± 0.92 mm), ToggleLoc (2.37 ± 1.08 mm), RigidLoop (2.01 ± 0.1 mm), and ProCinch (1.75 ± 0.19 mm). The UltraButton displayed the largest stiffness coefficient (1347.22 ± 136.33 N/mm) followed by the RigidLoop (1325.4 ± 116.37 N/mm), ToggleLoc (1216.62 ± 131.32 N/mm), ProCinch (1155.56 ± 88.04), and TightRope (848.48 ± 31.94). The ToggleLoc displayed the largest load to failure (1874.42 ± 101.08 N) followed by the RigidLoop (1614.12 ± 129.11 N), UltraButton (1391.69 ± 142.04 N), ProCinch (1384.85 ± 58.62 N), and TightRope (991.8 ± 51.1 N.). Conclusion: The 5 ALDs exhibited different biomechanical properties. None of them had peak cumulative displacements for which the confidence interval lay above 3 mm, thus no single device was determined to have a higher rate of clinical failure compared with the others. Clinical Relevance: ALD choice may affect biomechanics after ACLR.

Blood Flow Restriction Training Using the Delfi System Is Associated With a Cellular Systemic Response.

PURPOSE: To determine the effects of blood flow restriction (BFR) exercise on CD34+ cells, platelets, white blood cells, neutrophils, lymphocytes, lactate, and glucose. METHODS: Healthy participants aged 20 to 39 years who were able to perform the exercise sessions were recruited. Participants underwent an experimental (EXP) occluded testing session and a control (CON) session using the Delfi Personalized Tourniquet System. Blood draws were performed prior to testing and immediately after the exercise session. Blood analysis consisted of a complete blood count as well as flow cytometry to measure peripheral CD34+ counts as a marker for hematopoietic progenitor cells. RESULTS: Fourteen men (aged 30.8 ± 3.9 years) volunteered. There was a significant increase in average CD34+ counts immediately after the EXP session only (3.1 ± 1.2 cells ⋅ µL-1 vs 5.2 ± 2.9 cells ⋅ µL-1, P = .012). Platelet counts were significantly elevated after both sessions, with the average increase being higher after the EXP session (mean difference [MD], 34,200/µL; P < .002) than after the CON session (MD, 11,600/µL; P < .002). White blood cell counts significantly increased after both the EXP (8,400 ± 2,200/µL vs 6,300 ± 1,600/µL; P < .001) and CON (MD, 900/µL; P < .001) sessions. There was a significant increase from baseline to immediately after exercise in the average number of lymphocytes (MD, 6.3%; P < .001) and, conversely, a significant decrease in the average neutrophil count (MD, 6.5%; P < .001) in the EXP session only. Lactate levels significantly increased in the EXP (MD, 6.1 mmol ⋅ L-1; P = .001) and CON (MD, 3.6 mmol ⋅ L-1; P = .001) groups. No changes in glucose levels were observed. CONCLUSIONS: Exercise with BFR causes a significant post-exercise increase in peripheral hematopoietic progenitor cells and platelets, beyond that of standard resistance training. CLINICAL RELEVANCE: BFR can be considered a way to manipulate point-of-care blood products such as platelet-rich plasma to increase product yield.

The In Vitro Effects of Bupivacaine on Cartilage-forming Tumor Cells.

INTRODUCTION: Bupivacaine is a commonly used local anesthetic that has been shown to be cytotoxic to articular chondrocytes and various tumor cells. This study evaluates the in vitro effects of bupivacaine on cartilaginous tumor cells. METHODS: Multiple different cartilaginous tumors were evaluated, including enchondromas, chondroblastomas, a low-grade chondrosarcoma, which were harvested from patients during tumor resection, and a grade-II chondrosarcoma SW1535 (ATCC HTB-94). The tumor cells were treated with 0.25% and 0.5% bupivacaine at various times points, and the result was compared with that of untreated tumor cells. Tumor cell viability and apoptosis were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay and flow cytometry. RESULTS: The tumors were analyzed in groups according to their pathologic diagnosis. Increasing periods of exposure to bupivacaine decreased the cell viability in all tumor samples. The cytotoxicity of 0.5% bupivacaine was significantly greater than that of 0.25% bupivacaine in all tumor cells tested. DISCUSSION: At clinically relevant concentrations, in vitro exposure to bupivacaine caused a decrease in cellular viability and an increase in the induction of apoptosis in a dose- and time-dependent manner in each of the tumor cells evaluated in this study.

The Benefits of an In-Office Arthroscopy in the Diagnosis of Unresolved Knee Pain.

We report a patient who developed persistent knee pain with mechanical symptoms after an uncomplicated patellofemoral arthroplasty. The etiology of his knee pain remained inconclusive following magnetic resonance imaging due to metallic artifact image distortion. With the use of an in-office needle arthroscopy, an immediate and definitive diagnosis was obtained, preventing an unnecessary surgery for a diagnostic arthroscopy. We discovered a lateral meniscus tear, an anterior cruciate ligament tear, and a medial femoral condyle chondral defect for which the patient underwent arthroscopic partial meniscectomy, ligament reconstruction, and osteochondral allograft transplantation, with resolution of his knee pain.