Stephen D. Fening

Quantifying Glenoid Bone Loss in Anterior Shoulder Instability Reliability and Accuracy of 2-Dimensional and 3-Dimensional Computed Tomography Measurement Techniques

Background: Glenoid support is critical for stability of the glenohumeral joint. An accepted noninvasive method of quantifying glenoid bone loss does not exist. Purpose: To perform independent evaluations of the reliability and accuracy of standard 2-dimensional (2-D) and 3-dimensional (3-D) computed tomography (CT) measurements of glenoid bone deficiency. Study Design: Descriptive laboratory study. Methods: Two sawbone models were used; one served as a model for 2 anterior glenoid defects and the other for 2 anteroinferior defects. For each scapular model, predefect and defect data were collected for a total of 6 data sets. Each sample underwent 3-D laser scanning followed by CT scanning. Six physicians measured linear indicators of bone loss (defect length and width-to-length ratio) on both 2-D and 3-D CT and quantified bone loss using the glenoid index method on 2-D CT and using the glenoid index, ratio, and Pico methods on 3-D CT. The intraclass correlation coefficient (ICC) was used to assess agreement, and percentage error was used to compare radiographic and true measurements. Results: With use of 2-D CT, the glenoid index and defect length measurements had the least percentage error (−4.13% and 7.68%, respectively); agreement was very good (ICC, .81) for defect length only. With use of 3-D CT, defect length (0.29%) and the Pico1 method (4.93%) had the least percentage error. Agreement was very good for all linear indicators of bone loss (range, .85-.90) and for the ratio linear and Pico surface area methods used to quantify bone loss (range, .84-.98). Overall, 3-D CT results demonstrated better agreement and accuracy compared to 2-D CT. Conclusion: None of the methods assessed in this study using 2-D CT was found to be valid, and therefore, 2-D CT is not recommended for these methods. However, the length of glenoid defects can be reliably and accurately measured on 3-D CT. The Pico and ratio techniques are most reliable; however, the Pico1 method accurately quantifies glenoid bone loss in both the anterior and anteroinferior locations. Future work is required to implement valid imaging techniques of glenoid bone loss into clinical practice. Clinical Relevance: This is one of the only studies to date that has investigated both the reliability and accuracy of multiple indicators and quantification methods that evaluate glenoid bone loss in anterior glenohumeral instability. These data are critical to ensure valid methods are used for preoperative assessment and to determine when a glenoid bone augmentation procedure is indicated.

Risk Factors for Manipulation After Total Knee Arthroplasty: A Pooled Electronic Health Record Database Study

A commercially available software platform, Explorys (Explorys, Inc., Cleveland, OH), was used to mine a pooled electronic healthcare database consisting of the medical records of more than 27 million patients. A total of 229,420 patients had undergone a total knee arthroplasty; 3470 (1.51%) patients were identified to have undergone manipulation under anesthesia. Individual risk factors of being female, African American race, age less than 60, BMI >30 and nicotine dependence were determined to have relative risk of 1.25, 2.20, 3.46, 1.33 and 1.32 respectively. Depressive disorder, diabetes mellitus, opioid abuse/dependence and rheumatoid arthritis were not significant risk factors. African Americans under the age of 60 at time of TKA had the greatest incidence of MUA (5.17%) and relative risk of 3.73 (CI: 3.36, 4.13).

Theoretical model of the effect of combined glenohumeral bone defects on anterior shoulder instability: A finite element approach†

The presence of either a Hill–Sachs or a bony Bankart defect has been indicated as a possible cause of subluxation and anterior shoulder dislocation. Previous studies investigated only the effects of isolated humeral or glenoid defects on glenohumeral instability. We investigated the effects on shoulder stability of both glenoid and humeral defects in the glenohumeral joint. A computer‐based finite element approach was used to model the joint. A generic model was developed for cartilage and bone of the glenoid and humerus, using previously published data, and experiments were analyzed using static analysis with displacement control in the anterior‐inferior direction. Simulations were run with a 50‐N compressive load in the presence of both isolated and combined defects to analyze reaction forces and distance to dislocation. The distance to dislocation for normal joint was 13.6 mm at 90° abduction, which reduced to 9.7, 0, and 0 mm for largest isolated humerus defect, glenoid defect, and certain combined defects, respectively. For combined defects, stability ratio was decreased to 0% from 43%. Our results suggest that in the setting of combined bone defects, stability may be reduced more than what is known for isolated defects alone.

Predictive anthropometric measurements for humeral head curvature.

BACKGROUND Estimation of size, shape, and curvature of the humeral head is important for shoulder replacement procedures and allograft transplantation, especially as we try to recreate normal anatomy. The purpose of this study was to investigate the value of various anthropometric measurements for predicting humeral head curvature. MATERIALS AND METHODS Cadaveric humeri were scanned with a 3-dimensional laser scanner. Length of the humerus, epicondylar breadth, and humeral head curvature were determined using data from the scans. A linear regression was performed for the length of the humerus, epicondylar breadth, gender, age, height, and weight. A stepwise linear regression with forward and backward substitution (α = 0.15) was performed for the most predictive variables from the initial linear regression. An equation for the prediction of humeral head radius of curvature was generated using this data. RESULTS The most predictive factors (R(2) > 0.5) were epicondylar breadth, height, sex, and humeral length. These 4 factors were included in a forward and backward stepwise regression. The resulting equation had an R(2) value of 0.812. CONCLUSION Of the predicted measurements evaluated, patient height, maximum humeral length, epicondylar breadth, and gender were most correlated with humeral head curvature. Including these 4 factors in a linear regression model increased the R(2) value to 0.812. If only a single measurement can be used to size the humeral head curvature, patient height will give the same accuracy as epicondylar breadth and can more easily be obtained. A patients height can help accurately predict the patients humeral head anatomy.

The effects of Latarjet reconstruction on glenohumeral instability in the presence of combined bony defects: A cadaveric model

Objectives: Recurrent glenohumeral instability is often a result of underlying bony defects in the glenoid and/or humeral head. Anterior glenoid augmentation with a bone block (i.e. Latarjet) has been recommended for glenoid bone loss in the face of recurrent instability. However, no study has investigated the effect of Latarjet augmentation in the setting of both glenoid and humeral head defects (Hill-Sachs Defects (HSD)). The purpose of this study was to evaluate the stability achieved through a Latarjet procedure in the presence of combined bony defects. Our hypothesis was that Latarjet augmentation would increase shoulder stability for glenoid defects with small HSD, but have limited success in cases with large concomitant HSD. Methods: Eighteen fresh-frozen cadaveric specimens were tested at combinations of glenohumeral abduction (ABD) angles of 20°, 40°, and 60° and external rotation (ER) angles of 0°, 40°, and 80°. Each experiment applied a 50N medial load on the humerus to replicate the static load of soft tissues, and then simulated anterior dislocation by translating the glenoid in an anterior direction. Translational distance and medial-lateral displacement of the humeral head, along with horizontal reaction forces, were recorded for every trial. Specimens were tested in an intact condition (no defect), different combinations of defects, and with Latarjet augmentation. The Latarjet was performed for 20% and 30% glenoid defects by transferring the specimen’s coracoid process anterior to the glenoid flush with the articulating surface. Results: Results are summarized in Fig. 1. The vertical axis represents the normalized distance to dislocation with respect to the values of the intact joint. The horizontal axis represents the varying sizes and combinations of bony defects. Latarjet augmentation improved stability for every combination of bony defects. At 20° ABD, 0°ER, and 20% glenoid defect size, the percentage of intact translation did not change with increasing HSD size, and the Latarjet augmentation increased percent intact translation to greater than 100 percent for all cases (Fig. 1A). However, at 60° ABD, 80° ER, and 20% glenoid defect size, increasing HSD size caused decreased stability, and Latarjet augmentation did not increase the percent intact translation to normal levels for HSD sizes greater than 30% (Fig. 1B). Conclusion: This is first study to investigate and quantify the effect of Latarjet reconstruction on anterior shoulder instability in the presence of combined humeral head and glenoid defects. Clinically, these results demonstrate that some degree of stability can be regained for combined bony Bankart and Hill-Sachs defects with a Latarjet procedure. However, for humeral defects larger than 30%, the HSD led to persistent instability in the abducted externally rotated position, even after the Latarjet procedure. Thus, directly addressing the humeral defect to restore the articular surface should be considered in these cases.

Transparency to Reduce Surgical Implant Waste

Background Rising health care costs and emphasis on value have placed the onus of reducing healthcare costs on the surgeon. Methods Financial data from 3,973 hip, knee, and shoulder arthroplasties performed at a physician owned orthopedic hospital was retrospectively reviewed over a two-year period. A wasted implant financial report was posted starting the second year of the study. Each surgeons performance could be identified by his peers. Results After posting of the financial report, 1.11% of all hip and knee arthroplasty cases had a waste event compared to 1.50% during the control year. Shoulder arthroplasty waste events occurred twice as often than that observed in hip and knee arthroplasty during the study period. A decrease in waste events was observed but was not statistically significant (p = 0.30). Conclusions Posting a non-blinded wasted implant data sheet was associated with a reduction in the number of wasted orthopedic surgical implants in this series, although the reduction was not statistically significant.

Anterior Instability of the Shoulder: Effect of Arm Position and Relative Contributions of Bony Bankart and Hill-Sachs Defects

Shoulder stability can be significantly reduced in the presence of bony defects. Bony Bankart and Hill-Sachs lesions are known causes for recurrent shoulder dislocation. It has been shown in literature that often these defects are present together during cases of recurrent dislocation.1 However, past studies have only analyzed the effects of isolated bony Bankart or Hill-Sachs lesions.2, 3 Recent studies have stated that a Hill-Sachs lesion that “engages” the anterior glenoid has a critical impact on shoulder stability.4 It is important to understand the relationship between these two bony defects, as this would lead to better management of the shoulders’ instability.Copyright

Joint Space Loss after Arthroscopic Partial Meniscectomy: Data from the Osteoarthritis Initiative

Objectives: Knee osteoarthritis (OA) is a prevalent disease that causes substantial disability and use of medical resources, and knee arthroscopy is frequently performed in patients with OA or at risk of developing OA. While meniscectomy has been associated with progression of OA in multiple studies, none have assessed progression of joint space width (JSW) loss compared to matched controls. The Osteoarthritis Initiative (OAI) provides a unique cohort to enable this evaluation. We hypothesize that JSW significantly decreases in meniscectomy patients versus matched controls within a one-year period, and that joint space loss continues to be more rapid in subsequent years. Methods: A prospective cohort study with matching was conducted using records from the OAI public use data sets. The cohort (n=4796) is contains the incidence subcohort (normal radiographs with risk of developing OA) and the progression subcohort (radiographic evidence of OA). Subjects have fixed-flexion radiographs taken at yearly intervals and validated measurements of JSW are performed. Additional details about the OAI and study design are publicly accessible at http://oai.epi-ucsf.org/datarelease/About.asp. 141 meniscectomy knees were identified and 141 controls were randomly selected while matching for subcohort, gender, study site, age, knee side, and year. Paired t-test was used to evaluate change in JSW over the first year in the 141 matched pairs. Repeated measures MANOVA with adjustment for age, gender, race, and BMI was used to assess longitudinal changes in JSW in a subset of 33 matched pairs with 4 years of JSW measurements available. Results: Meniscectomy and control groups were balanced with respect to age, gender, race, BMI, and baseline JSW. The JSW decrease overa 1-year period was 0.948 mm in meniscectomy knees and 0.137 mm in controls p<0.0001). Table 1 shows similar results when stratifying by subcohort. In the crude and adjusted analyses of knees with 4 years of follow-up, the rate of JSW loss after the first year was not significantly different between meniscectomy knees and controls as shown in Figure 1. Conclusion: Arthroscopic partial meniscectomy is associated with increased loss of JSW during the first year after surgery in knees with OA and knees at risk of developing OA; however, the rate of JSW loss is not accelerated over the next 3 years. Immediate JSW narrowing may occur due to loss of the interposed meniscus, due to morphologic changes such as flattening and extrusion, or due to rapid degeneration of articular cartilage in response to increased tibiofemoral contact stress. Significance among both subcohorts suggests that meniscectomy causes progression of osteoarthritis independent of disease stage. Future investigation of change in cartilage and meniscal volumes on MR imaging may further explain the cause of this joint space loss.

The Effect of Arm Position on Hill-Sachs Engagement: A Finite Element Study

Bony lesions of the glenohumeral joint are important risk factors that often lead to recurrent anterior shoulder dislocation. A Hill-Sachs lesion is defined as bone loss from the posterior-superior aspect of the humeral head due to a compression fracture. It has been shown that the Hill-Sachs lesion is present in about 80% of initial dislocation cases and almost 100% of recurrent dislocations cases. The importance of the engaging Hill-Sachs lesion has been described by Burkhart and De Beer. The lesion is considered “engaging” when its long axis is parallel to the anterior glenoid, with the shoulder in a functional position of humero-thoracic abduction and external rotation.Copyright