Jacqueline Munch

Reconstruction of a Bony Bankart Lesion Best Fit Based on Radius of Curvature

Background: The inferior coracoid process has traditionally been considered to be the gold standard for glenoid augmentation after anteroinferior bone loss. Other autograft sites, and more recently, osteochondral allograft sites, have been described as potential donor sources. Purpose: Potential autograft and osteochondral allograft sites were compared to identify the graft source that would provide the best fit for glenoid augmentation. Study Design: Controlled laboratory study. Methods: Mose circles, a geometric tool found on a standard goniometer, were used to make radius of curvature measurements of 10 anatomic locations in 17 cadaveric specimens. The bony surface of the glenoid, measured from superior to inferior (G-SI) and from anterior to posterior (G-AP), was used as the standard for comparison. Autograft sites were the inferior coracoid, lateral coracoid, and inner table of the iliac crest. Potential osteochondral allograft sites were the radial head, scaphoid fossa of the distal radius (S-DR), lunate fossa of the distal radius (L-DR), medial tibial plateau, and lateral distal tibia. An acceptable match for autograft sites was based on a paired analysis and defined as a radius of curvature within 5 mm of the G-SI or the G-AP of the same cadaveric specimen. Allograft sites were evaluated using an unpaired analysis in which an ideal fit was defined as a radius of curvature of 25 to 30 mm, based on the interquartile range of the G-SI and G-AP. Results: The median (interquartile range) radii of curvature for the G-SI and G-AP were 30 mm (range, 25-30 mm) and 25 mm (range, 25-25 mm), respectively. The inferior coracoid was within 5 mm of the G-SI 59% of the time and the G-AP 94% of the time; no measurements from the lateral coracoid or iliac crest were within the range of the glenoid radius of curvature. Analysis of the allograft sites demonstrated an acceptable fit for 94% of the distal tibia, 68% of the medial tibial plateau, 12% of the S-DR, and 0% of the L-DR and the radial head specimens. Conclusion: An autograft of the inferior coracoid or an osteochondral allograft of the lateral distal tibia provided the best match to re-establish the native radius of curvature of the glenoid. Clinical Relevance: To best re-create the native glenohumeral anatomy, surgeons should consider the use of an autograft of the inferior coracoid or an osteochondral allograft of the lateral distal tibia for the reconstruction of osseous glenoid defects.

Anisometry of Medial Patellofemoral Ligament Reconstruction in the Setting of Patella Alta and Increased Tibial Tubercle-Trochlear Groove (TT-TG) Distance

Objectives: Medial patellofemoral ligament (MPFL) reconstruction is a common procedure to treat recurrent patellofemoral instability. However, the effects of an elevated tibial tubercle-trochlear groove (TT-TG) distance and patella alta, as measured by the Caton-Deschamps (C/D) ratio, on MPFL isometry remain unclear. We hypothesized that increased lateralization and proximalization of the tibial tubercle (TT) will have increasingly adverse effects on the isometry of the MPFL. Methods: Ten fresh-frozen cadaveric knees were placed on a custom testing fixture, with a fixed femur and tibia mobile through 120 degrees of flexion. The quadriceps tendon was loaded with 10.8 N in an anatomic direction using a weighted pulley system. A 0.2 N patellar lateral displacement load was used to simulate an intact lateral retinaculum to avoid over-medializing the patella. A tunnel was drilled under fluoroscopic guidance from Schottle’s point on the medial distal femur through the lateral cortex. A suture anchor was placed at the upper 66% of the medial border of the patella and the sutures were shuttled through to the lateral side and attached to a pulley with a 1 N weight. Retroreflective markers were attached to the femur, tibia, patella, and suture. MPFL length change, as measured by suture marker motion, was assessed using a 3D motion capture system through a range of motion between 0 deg and 110 deg with the native TT anatomy. Recordings were repeated after a flat TT osteotomy and transfer to a TT-TG of 20 mm and 25 mm and a C/D ratio of 1.2 and 1.4, including all combinations. Generalized estimating equation (GEE) modeling technique was used to analyze and control for the clustered nature of the data. SAS version 9.3 (SAS Inc., Cary, NC) was used for all data analyses. Results: Analysis was performed on 9 specimens secondary to significant deviations in the baseline normative data. Intact knees showed MPFL isometry through 20-70 degrees range of motion. Tibial tubercle lateralization significantly altered MPFL isometry with a threshold TT-TG of 25 mm (p=0.045) (Figure 1). Patella alta significantly altered MPFL isometry with a threshold C/D of 1.4 (p=0.025) (Figure 2). The effect of TT lateralization combined with patella alta compounded the anisometry, lowering the threshold for patella alta to a C/D of 1.2 when combined with a TT-TG of 25 mm (P<0.001) (Figure 3). Conclusion: Increased TT lateralization and proximalization significantly alter MPFL isometry. Tibial tubercle transfer should be considered when performing an MPFL reconstruction for recurrent patellofemoral instability in the setting of significant patella alta, elevated TT-TG and especially when both are present as an isolated MPFL reconstruction may be prone to failure given the anisometry demonstrated.

Patellar Articular Overlap on MRI Is a Simple Alternative to Conventional Measurements of Patellar Height

Background: Patella alta describes an abnormally high-riding patella in relationship to the femur and has been shown to correlate with patellofemoral pain, instability, chondromalacia, and arthrosis. Conventional measurements of patella alta involve multiple measurements and are often not defined on cross-sectional imaging as related to radiographs. Hypothesis: Patellar articular overlap on sagittal magnetic resonance imaging (MRI) will correlate well with conventional measurements of patella alta as measured by a standardized technique defined by our group. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: MRIs of 239 knees were reviewed by 3 attending surgeons with practices focusing on patellofemoral disease, as well as 2 sports medicine fellows and 1 musculoskeletal radiologist. Measurements included articular overlap, percentage of articular coverage, Caton-Deschamps index, Blackburne-Peel index, and modified Insall-Salvati index. Results: Interrater reliability was high for Caton-Deschamps, Blackburne-Peel, and modified Insall-Salvati indices (intraclass correlation coefficient [ICC], 0.877, 0.828, and 0.787, respectively). Articular overlap and percentage articular coverage correlated well with each other (ICC, 0.961; P < .001) and with the Caton-Deschamps (overlap r = –0.271, P < .001; coverage r = –0.131, P = .037) and Blackburne-Peel (overlap r = 0.343, P < .001; coverage r = –0.238, P < .001) indices. Articular overlap and percentage coverage failed to correlate with the modified Insall-Salvati index (overlap r = –0.117, P = .091; coverage r = 0.007, P = .918). Conclusion: Patellar articular overlap and percentage of patellar articular coverage show promise as a simpler alternative to conventional, ratio-based measurements of patellar height. Future studies are needed to evaluate the range of normal and the relationship to our traditionally used measurements.

A scoring system to predict postoperative medical complications in high-risk patients undergoing elective thoracic and lumbar arthrodesis.

BACKGROUND CONTEXT Various surgical factors affect the incidence of postoperative medical complications following elective spinal arthrodesis. Because of the inter-relatedness of these factors, it is difficult for clinicians to accurately risk-stratify individual patients. PURPOSE Our goal was to develop a scoring system that predicts the rate of major medical complications in patients with significant preoperative medical comorbidities, as a function of the four perioperative parameters that are most closely associated with the invasiveness of the surgical intervention. STUDY DESIGN/SETTING This study used level 2, Prognostic Retrospective Study. PATIENT SAMPLE The patient sample consisted of 281 patients with American Society of Anesthesiologists (ASA) scores of 3-4 who underwent elective thoracic, lumbar, or thoracolumbar fusion surgeries from 2007 to 2011. OUTCOME MEASURES Physiologic risk factors, number of levels fused, complications, operative time, intraoperative fluids, and estimate blood loss were the outcome measures of this study. METHODS Risk factors were recorded, and patients who suffered major medical complications within the 30-day postoperative period were identified. We used chi-square tests to identify factors that affect the medical complication rate. These factors were ranked and scored by quartiles. The quartile scores were combined to form a single composite score. We determined the major medical complication rate for each composite score, and divided the cohort into quartiles again based on score. A Pearson linear regression analysis was used to compare the incidence of complications to the score. RESULTS The number of fused levels, operative time, volume of intraoperative fluids, and estimated blood loss influenced the complication rate of patients with ASA scores of 3-4. The quartile ranking of each of the four predictive factors was added, and the sum became the composite score. This score predicted the complication rate in a linear fashion ranging from 7.6% for the lowest risk group to 34.7% for the highest group (r=0.998, p<.001). CONCLUSIONS Taken together, the four factors, though not independent of one another, proved to be strongly predictive of the major medical complication rate. This score can be used to guide medical management of thoracic and lumbar spinal arthrodesis patients with preexisting medical comorbidities.

Clinical Outcomes after Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability

Objectives: Medial patellofemoral ligament (MPFL) reconstruction has become an increasingly popular means to regain stability in the setting of recurrent lateral patellar dislocation, with nearly twice the number of medical centers performing reconstruction of the MPFL and outcomes reported on nearly double the number of patients in recent years. While recent studies have demonstrated improved patient reported outcome measures and a high rate of return to sports, limited literature has explored its effectiveness as an isolated intervention in the context of trochlear dysplasia. The purpose of this study was to determine the efficacy of isolated MPFL reconstruction in treating patellar instability in the setting of trochlear dysplasia. Methods: This was a retrospective review of consecutive patients who underwent unilateral or bilateral medial patellofemoral ligament reconstruction for patellofemoral instability. No osteotomies were included. All patients with minimum 2 year follow up were included. Pre- and postoperative assessment included ligamentous laxity, patellar crepitus, tilt, translation, and apprehension, and radiographic features including tibial tubercle-trochlear groove (TT-TG) ratio, Dejour classification, and Caton Deschamps ratio. Final follow up consisted of patient reported outcome measures including the Kujala score, International Knee Documentation Committee (IKDC) score, Lysholm score, and visual analog scale (VAS). Results: 105 MPFL reconstructions were included. Average age at surgery was 23.8 years (SD 9.7, range 12.1 - 57.0) with an average BMI of 23.4 (SD 4.7, range 16.3-43.6) and an average of 4.4 (SD 6.8) dislocation events prior to surgery. Average follow up was 44 months (range 24-111). 76% of patients were female. Average preoperative TT-TG ratio was 13.5 (SD 3.9, range 3.2-22) and Caton Deschamps ratio was 1.2 (SD 0.2, range 0.9-1.6); 74.5% of patients had Dejour C or D trochlear grooves. Kujala score improved from 54.5 (SD 3.8) preoperatively to 87.2 (SD 2.1) at 2 year follow up (p < 0.0001), Lysholm improved from 57.7 (SD 3.6) to 86.4 (SD 2.0) (p < 0.0001), IKDC improved from 52.1 (SD 3.8) to 79.5 (SD 2.6) (p < 0.0001), and VAS pain score improved from 2.9 (SD 0.3) to 1.7 (SD 0.3) (p<0.017). 78.9% of patients were able to return to sports at 1 year, with 69% returning to the same or higher level of play. At minimum 2-year follow up, only 5 patients reported either a postoperative dislocation or subluxation event. Conclusion: This study is the largest single series to report on the effectiveness of isolated MPFL reconstructions in a cohort of patients with a high incidence of trochlear dysplasia. In patients with normal TT-TG ratios, isolated medial patellofemoral ligament reconstruction provides safe and effective treatment for patellofemoral instability, despite the presence of Dejour class C or D trochlear grooves. Most patients are able to return to sports by 1 year postoperatively at the same or higher level of play.