Neutral Inclination Research Articles

DOES THE FALSE PROFILE VIEW REALLY SHOW ANTERIOR COVER?

To quantify the acetabular coverage of the femoral head, Lequesne's vertical-center-anterior edge (VCA) angle is used on the false profile view. Lateral coverage is determined by Wiberg's lateral-center-edge (LCE) angle on an ap pelvic view. The delimitation of the weightbearing area is defined by the end of the subchondral sclerosis line for both views. To our knowledge the exact anatomic location of the points used for measurement on the acetabular rim are not known.Six hips from three cadaver pelvises (3 male and 3 female) were investigated. The anterior and lateral points of interested were identified radiographically using fluoroscopy and marked with 1mm ceramic bullets. Standard false profile views and ap pelvic views in neutral inclination and rotation were taken to check the correct location of the ceramic bullets. A CT of each pelvis was made to locate the ceramic bullets and to define the exact anatomic location of the measurement points on the o'clock position. 6 o‘clock was defined as the midpoint between anteroinferior and the posteroinferior rim edges. Values were normalized for a right hip.The mean clockface location for the VCA was 1:33 (range, 1:15 to 1:40) and for the LCE 0:38 (range, 0:20 to 0:50).The LCEA is slightly anterior to the 12 o'clock position and remains useful to quantify the lateral coverage. Surprisingly, the point used for measuring the VCA is only about 30° (1h) anterior of the point used for measuring the LCEA. Its value for determining anterior cover has to be questioned. The discrepancy to other studies in the literature is because this study identifies and measures the end of the weight bearing zone, and not the border of the bony acetabulum.

Baseplate augmentation strategies: optimizing range of motion with reverse shoulder arthroplasty based upon variable glenoid deformity

Various operative strategies exist to address glenoid deformity in patients undergoing reverse shoulder arthroplasty (RSA). There is lack of guidance in pairing operative strategies with type and severity of deformity especially with regard to glenoid lateralization, humeral lateralization, and global lateralization. The purpose of this study is to compare different glenoid baseplates on their ability to provide optimal glenoid lateralization and improve range-of-motion based upon pattern and severity of deformity in glenohumeral osteoarthritis. CT scans were chosen from a large database of osteoarthritic shoulders until ten from each of the following three cohorts were identified: 1) no deformity: retroversion <10° and inclination deformity <5°, 2) Uniplanar deformity: retroversion >15° and inclination <10° or, 3) biplanar deformity: retroversion >15° and inclination >15°. Imascap SAS (Wright Medical) was used to quantify deformities and plan RSA placement. Each case was planned with the following baseplates: standard implant, three mm lateralized, wedge augment, and patient-specific implant. Each baseplate was placed in 5° of retroversion and neutral inclination and medialized to 70% seating. Percent seating, amount of reaming, global lateralization, and simulated range of motion (ROM) was recorded for each scenario. The average patient age was 65.4 (49-78) and 14 (47%) were women. Ten of thirty (33%) were classified as Walch A1 or A2, 19/30 (63%) were B1, B2, or B3, and 1/30 (5%) was a C. The normal, uniplanar, and biplanar groups had mean retroversion deformities of 2.1° (-3- 8°), 28.4° (22-36°), and 29.3° (19-39°) respectively. Across the three cohorts, increased global lateralization through glenoid-sided lateralization provided improved ROM most significantly in adduction (R = 0.82; P <.001), flexion (R = 0.78; P <.001), and external rotation (R = 0.76; P <.001). In the nodeformity cohort, less global lateralization was needed for improved range of motion compared to uniplanar and biplanar cohorts. In uniplanar deformities, the wedge augment provided similar amounts of added global lateralization as the patient-specific augment (7.2 mm vs 8.5mm; P = .06) and was equally able to improve range of motion. In the biplanar group, the patient-specific provided greater global lateralization than wedge augment when compared to standard implants (10.1mm vs 7.1mm; P = .002) and improved ROM. When RSA is used in the treatment for glenohumeral arthritis, the degree of deformity should be considered when choosing baseplate implants. Increased global lateralization is needed to optimize ROM in the setting of severe deformities and in select cases an augment wedge or patient-specific implant construct should be considered. Level III, retrospective comparative study.

Can surgeons optimize range of motion and reduce scapulohumeral impingements in reverse shoulder arthroplasty? A computational study.

Early glenohumeral impingement leads to poor range of motion and notching in reverse shoulder arthroplasty. The aim was to find from planning software which implant configuration provides the best motions in reverse shoulder arthroplasty. Reverse shoulder arthroplasty planning (Glenosys) was made in 31 patients (12 men, 19 women, 76 ± 6 yo) and impingements were analyzed. Inlay (155°-inclined) and Onlay (145°-inclined) humeral designs were tested. Four configurations were tested for each shoulder: "INLAY": non-lateralized glenoid-inlay humerus, "BIO-INLAY": lateralized glenoid (BIO-RSA)-inlay humerus, "ONLAY": non-lateralized glenoid-onlay humerus, and "BIO-ONLAY": lateralized (BIO-RSA) glenoid-onlay humerus. BIO-ONLAY and BIO-INLAY groups presented a significantly better result in all tested motion (p < 0.001 for all tests). BIO-ONLAY allowed a significantly better external rotation, extension and adduction than BIO-INLAY with decreased impingements with the pilar. BIO-INLAY presented a significantly better abduction. In abduction, an abutment of the greater tuberosity against the acromion was associated with a lower range of motion (p < 0.0001) and did not depend on the lateralization. Glenoid lateralization delays the glenohumeral impingement in reverse shoulder arthroplasty and gives the best rotations, adduction and extension when associated with neutral inclination and humeral 145° inclination. Greater tuberosity abutment has to be avoided in abduction and the Inlay design provides the best abduction.

Bony increased-offset–reverse shoulder arthroplasty: 5 to 10 years' follow-up

Glenoid lateralization has been shown to be the most imortant factor in maximizing passive range of motion and shoulder stability while preventing scapular impingement and notching. We aimed to evaluate mid- to long-term functional and radiologicoutcomes after bony increased-offset-reverse shoulder arthroplasty (BIO-RSA) using a Grammont-style (medialized) humeral implant. The study included 143 consecutive shoulders (140 patients; mean age, 72 years)treated with a BIO-RSA for rotator cuff deficiency. A cylinder of autologous cancellous bone graft, harvested from the humeral head, was placed between the reamed glenoid surface and baseplate; fixation was achieved using a long central peg (25 mm) and 4 screws. A large baseplate (29 mm) with a small baseplate sphere (36 mm) was used in 77% of cases, and a Grammont-style (medialized) humeral implant with 155° of inclination was used in all cases. All patients underwent clinical and radiographic assessment at a minimum of 5 years after surgery; in addition, 86 cases (60%) underwent computed tomography scan assessment. At a mean follow-up of 75 months (range, 60-126 months), the survivorship of the BIO-RSAusing revision as an endpoint was 96%. No cases of dislocationor humeral loosening were observed. Overall, 118 patients (83%) were either very satisfied (61%) or satisfied (22%). The adjusted Constant score improved from 40% ± 18% to 93% ± 23%, and the Subjective Shoulder Value improved from 31% ± 15% to 77% ± 18% (P < .001). The humeral bone graft incorporated completely in 96% of cases (137 of 143). Severe inferior scapular notching (grade 3 or 4) occurred in 18% (24 of 136). The risk of postoperative notching correlated to a lower body mass index (P < .05), superior glenosphere inclination (P = .02), and high or flush glenosphere positioning (P = .035). BIO-RSA is a safe and effective technique to lateralize the glenoid, providing consistent bone graft healing, excellent functional outcomes, a low revision rate, and a high rate of patient satisfaction. Thin patients (with a low body mass index) and glenosphere malposition (with persistent superior inclination and/or insufficient lowering of the baseplate and sphere) are associated with higher risk of scapular notching.Our data confirm the importance of implanting the baseplate with a neutral inclination (reverse shoulder arthroplasty angle < 5°) and with sufficient glenosphere inferior overhang (>5 mm) in preventing scapular notching. The use of a less medialized humeral implant (135° or 145° inclined) and smaller (25-mm) baseplate (when using a small, 36-mm sphere) should allow reduction in the incidence of scapular notching.