Andrew S. Bernhardson

Correlation of Valgus Stress Radiographs With Medial Knee Ligament Injuries An In Vitro Biomechanical Study

Background The amount of medial compartment opening for medial knee injuries determined by valgus stress radiography has not been well documented. The purpose of this study was to develop clinical guidelines for diagnosing medial knee injuries using valgus stress radiography. Hypothesis Measurements of medial compartment gapping can accurately differentiate between normal and injured medial structure knees on valgus stress radiographs. Study Design Controlled laboratory study. Methods Valgus stress radiographs were obtained on 18 adult lower extremities using 10-N·m and clinician-applied valgus loads at 0° and 20° of flexion to intact knees and after sequential sectioning of the superficial medial collateral ligament proximally and distally, the meniscofemoral and meniscotibial portions of the deep medial collateral ligament, the posterior oblique ligament, and the cruciate ligaments. Three independent observers of different experience levels measured all of the radiographs during 2 separate occasions to determine intraobserver repeatability and interobserver reproducibility. Results Compared with the intact knee, significant medial joint gapping increases of 1.7 mm and 3.2 mm were produced at 0° and 20° of flexion, respectively, by a clinician-applied load on an isolated grade III superficial medial collateral ligament simulated injury. A complete medial knee injury yielded gapping increases of 6.5 mm and 9.8 mm at 0° and 20°, respectively, for a clinician-applied load. Intraobserver repeatability and interobserver reproducibility intraclass correlation coefficients were .99 and .98, respectively. Conclusion Valgus stress radiographs accurately and reliably measure medial compartment gapping but cannot definitively differentiate between meniscofemoral- and meniscotibial-based injuries. A grade III medial collateral ligament injury should be suspected with greater than 3.2 mm of medial compartment gapping compared to the contralateral knee at 20° of flexion, and this injury will also result in gapping in full extension. Clinical Significance Valgus stress radiographs provide objective and reproducible measurements of medial compartment gapping, which should prove useful for definitive diagnosis, management, and postoperative follow-up of patients with medial knee injuries.

Snapping biceps femoris tendon treated with an anatomic repair

Three patients were seen for pain and snapping over the lateral aspect of their symptomatic knee during deep knee flexion. On physical examination, each patient had subluxation of the long head of the biceps over the lateral aspect of the fibular head. Each patient underwent an anatomic repair of the torn anterior arms of the short and long biceps femoris to their anatomic insertion sites with suture anchors. All patients had normal return of function without pain or further subluxation events.

Hip Arthroscopy for Femoroacetabular Impingement in a Military Population

Background: Femoroacetabular impingement (FAI) can lead to hip pain and early joint degeneration. There have been few reports to date on the outcomes of hip arthroscopy for the treatment of FAI in the military population. Purpose/Hypothesis: The purpose of this study was to compare patient demographics with postoperative outcomes after hip arthroscopy for symptomatic FAI and to identify preoperative risk factors for poor outcomes. The hypothesis was that certain preoperative patient characteristics will be predictive of poorer outcomes and that lower outcomes scores will be associated with a higher likelihood of medical separation from the military. Study Design: Case series; Level of evidence, 4. Methods: Retrospective chart review of active-duty and dependent patients older than 18 years who underwent hip arthroscopy for symptomatic FAI from 2009 to 2014 at a single institution. Results: A total of 469 (309 males and 160 females) surgeries were performed on 456 active-duty personnel and 13 dependent civilians, with a mean 2.5-year follow-up. Overall, 39% (n = 179) were able to return to duty (RTD), 18% (n = 82) were medically cleared to return to normal daily activities but did not remain on active duty, and 43% (n = 195) required referral to the Disability Evaluation System (DES). Increasing rank and male sex were positive predictors and Axis 1 psychiatric diagnosis, revision surgery, concomitant psoas tenotomy, multiple medical comorbidities, and complaints of generalized pelvic pain were negative predictors for returning to duty. US Marine Infantry and Special Forces showed improved RTD rates (50%-86%) compared with administrative, more sedentary, occupations (22%). On average, Single Alpha Numeric Evaluation (SANE) and visual analog scale (VAS) scores improved after surgery, with SANE scores improving 37 ± 28 points and VAS scores improving 2.6 ± 2.5 points. The mean postoperative SANE and VAS scores differed significantly between the RTD group and those not returning to duty; 87 and 1.2 points compared with 69 and 3.6 points, respectively (P < .0001). Conclusion: Hip arthroscopy for the treatment of symptomatic FAI effectively improves pain symptoms and self-reported overall function but shows a much lower than expected return to full, unrestricted active duty in the general active-duty military population. Underlying psychiatric diagnoses, female sex, and more sedentary occupations are associated with lower RTD rates. Furthermore, lower postoperative SANE and VAS scores are associated with lower RTD rates. Only the more active and elite components of the military study population showed RTD rates consistent with previously reported outcomes of return to competitive sports after hip arthroscopy for FAI.

Biomechanical Comparison of Screw Fixation Versus a Cortical Button and Self-tensioning Suture for the Latarjet Procedure

Background: Metal screws are traditionally used to fix the coracoid process to the glenoid. Despite stable fixation, metal screws have been associated with hardware complications. Therefore, some studies have advocated for suture button fixation during the Latarjet procedure to reduce the complications associated with screw fixation. Purpose: To biomechanically evaluate the ultimate failure load of a cortical button and self-tensioning suture versus metal screws for coracoid graft fixation during the Latarjet procedure. Study Design: Controlled laboratory study. Methods: Eight matched pairs of fresh-frozen, male cadaveric shoulders (N = 16) underwent the Latarjet procedure. The shoulders of each pair were randomly assigned to 1 of 2 groups: fixation using two 3.75-mm cannulated, fully threaded metal screws or fixation using a double suture button construct. Specimens were secured in a dynamic testing machine and cyclically preconditioned from 2 to 10 N at 0.1 Hz for 10 cycles. After preconditioning, specimens were pulled to failure at a normalized displacement rate of 400% of the measured gauge length per minute. The ultimate failure load and mechanism of failure were recorded for each specimen. Results: The mean ultimate load to failure for screw fixation (226 ± 114 N; 95% CI, 147-305 N) was not significantly different from that for suture button fixation (266 ± 73 N; 95% CI, 216-317 N) (P = .257). The mean strain at failure for screw fixation (63% ± 21%; 95% CI, 48%-77%) was not significantly different from that for suture button fixation (86% ± 26%; 95% CI, 69%-104%) (P = .060). The most common mechanism of failure for the screw fixation method was at the bone block drill holes, while an intramuscular rupture at the clamp-muscle interface occurred for the suture button construct. Conclusion: The screw and suture button fixation techniques exhibited comparable biomechanical strength for coracoid bone block fixation of the Latarjet procedure. Clinical Relevance: Metal screws have been reported to be a large contributor to intraoperative and postoperative complications. Therefore, given the results of the current study, a suture button construct may be an alternative to metal screw fixation during the Latarjet procedure. However, further clinical studies are warranted.

Blood Flow Restriction Therapy After Knee Surgery: Indications, Safety Considerations, and Postoperative Protocol

Blood flow restriction (BFR) training involves occluding venous outflow while maintaining arterial inflow by the application of an extremity tourniquet after surgery. BFR ultimately reduces oxygen delivery to muscle cells, similar to an anaerobic environment, and allows patients to exercise with low resistance and stimulates muscle hypertrophy and strength using heavy resistance. Thus orthopaedic surgeons and physical therapists are incorporating this type of training into their postoperative rehabilitation protocols, particularly after injuries or surgical procedures about the knee joint. The purpose of this Technical Note is to describe a BFR clinical application technique and to report on the indications, safety considerations, and postoperative knee surgery rehabilitation protocols for BFR.

Surgical Repair of Dynamic Snapping Biceps Femoris Tendon

A snapping biceps tendon is an infrequently seen and commonly misdiagnosed pathology, leaving patients with persistent symptoms that can be debilitating. Patients will present with a visible, audible, and/or painful snap over the lateral aspect of their knee when performing squats, sitting in low seats, or participating in activities with deep knee flexion. A thorough knowledge of the anatomy is essential for surgical treatment of this pathology, which is caused by a detachment of the direct arms of the long and short heads of the biceps femoris off the fibular styloid. This Technical Note provides a diagnostic approach, postoperative management, and details of a surgical technique to treat a snapping biceps tendon with an anatomic repair of the long and short head attachments of the biceps femoris to the posterolateral fibular styloid.