Press-fit reverse shoulder arthroplasty in case of advanced humeral bone loss - Is additional distal fixation necessary for primary stability?

BACKGROUND: Revision reverse shoulder arthroplasty (RSA) poses considerable surgical challenges. We hypothesized that a newly developed press-fit stem, which is modeled on the medullary canal of the supracondylar region of the distal humerus by a slight distal bend, achieve both correct fit and sufficient primary stability and that additional distal fixation by interlocking screws is favorable in case of advanced humeral bone loss. METHODS: A modular tapered press-fit stem was implanted in 16 Sawbone humeri in three consecutively created defect situations (200 mm (experimental group type 3°), 160 mm (type 4°) and 120 mm (type 5°) bone length above the epicondylar line. In experimental groups type 4° and 5°, additional distal interlocking screw fixation with one to three screws was tested. Primary stability was investigated by measuring micromotions with a high-precision rotational setup. FINDINGS: Highest relative micromotions were noted at the proximal end in experimental groups type 3° and type 4°, whereas in type 5° highest micromotions could be seen at the distal end. Overall micromotions were significantly lower in type 3° and increased with extended defect size. In experimental group type 5°, micromotions increased with reduced additional distal screw fixation. INTERPRETATION: The examined press-fit stem did not provide sufficient primary rotational stability in all constructs without additional support. Advanced distal humeral bone loss had a strong impact on primary fixation. In experimental group type 5° with 120 mm bone remaining, it might be beneficial to use three distal interlocking screws in the supracondylar region in order to neutralize torque and to avoid early loosening.

The implications of the glenoid angles and rotator cuff status in patients with osteoarthritis undergoing shoulder arthroplasty.

BACKGROUND: The success of shoulder arthroplasty, both reverse and anatomical, depends on correcting the underlying glenoid deformity especially in patients with an osteoarthritis. We hypothesized that the distribution of glenoid version and especially inclination are underestimated in the shoulder arthritis population, and also that superior glenoid inclination can be detected through 3-dimensional (3D) software program of computed tomography (CT) to a greater proportion in patients with rotator cuff insufficiency, but also in patients with osteoarthritis with an intact rotator cuff. Because of the influence of rotator cuff imbalance on secondary glenoid wear the values of the critical shoulder angle (CSA) and the fatty infiltration of the rotator cuff are further analyzed. The aim of our study is to determine; 1) the distribution of glenoid inclination and version; 2) the relationship between glenoid inclination, version, the critical shoulder angle (CSA) to the status of the rotator cuff; 3) the proportion of patients with both an intact rotator cuff and a superior inclination greater than 10°. METHODS: A total of 231 shoulders were evaluated with X-ray images, 3-dimentional (3D) software program of computed tomography (CT), and magnetic resonance imaging. The cohort was divided into 3 groups according to their inclination angles and also grouped as intact-rotator cuff and torn-cuff group. RESULTS: The median (min/max) values for the 231 shoulders were 8° (- 23°/56°) for the inclination angle, - 11°(- 55°/23°) for the version angle, and 31.5°(17.6°/61.6°) for the CSA. The majority of the glenoids were found to show posterior-superior erosion. Glenoid inclination angle and CSA were significantly higher in torn-cuff group when compared with intact-cuff group (P < 0.001, both). The rotator cuff tears were statistically significant in high inclination group than low inclination group and no inclination group (p < 0.001). In the high inclination group, 41 of 105 (39%) shoulders had an intact rotator cuff, in about 18% of all shoulders. CONCLUSION: Our findings show that 3D evaluation of glenoid inclination is mandatory for preoperative planning of shoulder replacement in order to properly assess superior inclination and that reverse shoulder arthroplasty may be considered more frequently than as previously expected, even when the rotator cuff is intact. LEVEL OF EVIDENCE: Level III.

Does arm lengthening affect the functional outcome in onlay reverse shoulder arthroplasty?

BACKGROUND: The concept of onlay design reverse shoulder arthroplasty has been introduced to overcome complications observed with the traditional Grammont-type prosthesis. The aim of this study was to determine the influence of arm lengthening on the short-term clinical outcome in onlay reverse shoulder arthroplasty and investigate the effect of humeral tray offset positioning on arm lengthening and range of motion. METHODS: We retrospectively evaluated 56 patients undergoing reverse shoulder arthroplasty with the Aequalis Ascend Flex prosthesis (Tornier, Bloomington, MN, USA) at a minimum 2 years' follow-up. Arm lengthening was determined using bilateral scaled radiographs of the entire humerus. The Constant score and active range of motion were documented preoperatively and postoperatively. The relationship between arm lengthening, humeral tray offset position, and functional outcome was analyzed. RESULTS: The Constant score improved from 25.5 ± 9.5 points to 71.5 ± 13.8 points at a mean follow-up of 30.1 ± 5.2 months. Mean postoperative anterior elevation was 145.2° ± 21.1°, and external rotation was 30.7° ± 20.3°. Arm lengthening exceeding 2.5 cm was related to a decrease in anterior elevation. We found a relationship between arm lengthening averaging 2.2 ± 1.7 cm and increased Constant score values. Humeral tray positioning demonstrated no influence on the functional outcome. There was a trend toward increased arm lengthening in lateral offset positioning. CONCLUSIONS: Onlay reverse shoulder arthroplasty yields good short-term clinical results. In our population, arm lengthening averaging 1 to 2.5 cm was found to be the best compromise on postoperative range of motion.

The influence of humeral neck shaft angle and glenoid lateralization on range of motion in reverse shoulder arthroplasty.

BACKGROUND: Recent developments in reverse shoulder arthroplasty (RSA) have focused on changes in several design-related parameters, including humeral component design, to allow for easier convertibility. Alterations in humeral inclination and offset on shoulder kinematics may have a relevant influence on postoperative outcome. This study used a virtual computer simulation to evaluate the influence of humeral neck shaft angle and glenoid lateralization on range of motion in onlay design RSA. METHODS: Three-dimensional RSA computer templating was created from computed tomography (CT) scans in 20 patients undergoing primary total shoulder arthroplasty for concentric osteoarthritis (Walch A1). Two concurrent factors were tested for impingement-free range of motion: humeral inclination (135° vs. 145°) and glenoid lateralization (0 mm vs. 5 mm). RESULTS: Decreasing the humeral neck shaft angle demonstrated a significant increase in impingement-free range of motion. Compared to the 145° configuration, extension was increased by 42.3° (-8.5° to 73.5°), adduction by 15° (10° to 23°), and external rotation with the arm at side by 15.1° (8.5° to 26.5°); however, abduction was decreased by 6.5° (-1° to 12.5°). Glenoid lateralization led to comparable results, but an additional increase in abduction of 7.6° (-1° to 16.5°) and forward flexion of 26.6° (6.5° to 62°) was observed. CONCLUSION: Lower humeral neck shaft angle and glenoid lateralization are effective for improvement in range of motion after RSA. The use of the 135° model with 5 mm of glenoid lateralization provided the best results in impingement-free range of motion, except for abduction.

The influence of three-dimensional planning on decision-making in total shoulder arthroplasty.

BACKGROUND: Long-term results and complication rates in shoulder arthroplasty are related to implant positioning. Current literature reports increased precision in glenoid component positioning using 3-dimensional (3D) computed tomography (CT) planning tools. This study evaluated the accuracy of glenoid version and inclination measurements using 2D CT scans compared with a validated 3D software program and its influence on decision making on implant selection. METHODS: Preoperative CT scans were obtained from 50 patients undergoing total shoulder arthroplasty. Glenoid version and inclination measurements were performed in random order by 3 independent qualified orthopedic surgeons on reformatted 2D CT scans. Indication for anatomic or reverse shoulder arthroplasty was based on glenoid deformity and on rotator cuff conditions. Results were compared with those from a validated 3D computer software program, and the final decision was made according to the 3D planning. RESULTS: Mean preoperative glenoid retroversion on reformatted 2D CT scans was 11.9° ± 9.6° and mean superior inclination was 10.7° ± 8.6°. When the 3D software was used, glenoid retroversion averaged 15.1° ± 10.6° and superior inclination averaged 8.9° ± 9.9°. The 2D CT demonstrated good interobserver and intraobserver reliability for glenoid version and inclination. Decision on the choice of implant was adjusted in 7 patients after the 3D planning. CONCLUSIONS: Our findings show that measurements of glenoid version and inclination on reformatted 2D CT scans are less accurate compared with 3D measurements. A preoperative 3D planning software allows for improvement of virtual glenoid positioning and influences the decision making process.

Long-term analysis of revision reverse shoulder arthroplasty using cemented long stems.

BACKGROUND: Revision of failed shoulder arthroplasty is often associated with poor results and a high rate of complications. Significant humeral bone loss after removal of long stems poses a considerable surgical challenge. Therefore, the aim of our study was the evaluation of the clinical and radiologic outcome of cemented long-stem humeral components in revision reverse shoulder arthroplasty with a minimum 5 years' follow-up. METHODS: Between June 2001 and June 2009, revision reverse shoulder arthroplasty using long-stem cemented humeral components was performed in 124 patients. Mean age at time of surgery was 69.6 years (range, 42-87 years). Complete clinical and radiographic data were available in 50 patients at a mean of 7 years (range, 5-11.6 years). Postoperative radiographs were evaluated for radiolucent lines, implant migration, fracture, and glenoid notching. RESULTS: The mean Constant score improved from 11.1 points (range, 0-27 points) to 39.5 points (range, 14-73 points) at the latest follow-up. Progressive humeral radiolucency was present in 24 patients, including 6 patients demonstrating complete loosening or progressive distal migration of the humeral stem. We noted an overall of 12 additional complications in 8 patients, necessitating revision surgery in 16. CONCLUSION: The use of long-stem humeral components is a beneficial treatment in revision reverse shoulder arthroplasty. Nevertheless, the high percentage of patients with humeral loosening is concerning. Modular cementless revision stems that are adapted to the distal humeral medullary canal and additional distal screw and cable fixation might enhance durable distal fixation in case of advanced bone loss.

Is radiographic measurement of acromiohumeral distance on anteroposterior view after reverse shoulder arthroplasty reliable?

BACKGROUND: Reverse shoulder arthroplasty leads to arm lengthening. Different techniques have been described to determine postoperative lengthening. The purpose of this study was to evaluate the reliability of the acromiohumeral distance (AHD) in determining arm lengthening after reverse shoulder arthroplasty. METHODS: At 2 centers, 44 patients who had received an onlay design reverse shoulder arthroplasty were observed for a minimum of 6 months. Examination followed a standardized protocol including preoperative and postoperative radiographs on anteroposterior view in neutral rotation. Two orthopedic surgeons independently performed the measurements in random order. RESULTS: Mean arm lengthening averaged 2.5 cm (range, 0.3-3.9 cm) according to AHD measurement. Significant differences in interobserver and intraobserver variability for postoperative AHD measurements were found (P < .01). The mean intrapatient difference was 0.5 cm (range, 0.02-1.5 cm). CONCLUSION: According to our study, the AHD is not a reliable measurement technique to determine arm lengthening after reverse shoulder arthroplasty.

Evaluation of lengthening in reverse shoulder arthroplasty comparing X-rays and computerised tomography.

PURPOSE: The correct amount of arm lengthening in reverse shoulder arthroplasty is crucial to provide joint stability and good results. Determination has been proposed according to radiographs. However, radiographic measurements are error prone in regards to positioning of the arm with regard to the radiographic beam. The purpose of this study was to evaluate the precision of radiographic measurements compared to CT scans of the upper limb following reverse shoulder arthroplasty. METHODS: Thirty patients undergoing onlay reverse shoulder arthroplasty with comparative radiographs and CT scans of both humeri were included in this study. Arm length, humeral length as well as the arm and humeral lengthening were evaluated on pre- and postoperative radiographs compared to postoperative CT scans following a previously validated protocol. RESULTS: We found an excellent correlation for arm length and humeral length for radiographic and CT measurements (r > 0.90). The postoperative humeral and arm lengthening compared to the contralateral side was 0.1 (-1.2 to 1.2) cm and 2.8 (0.2 to 5.2) cm for the CT scans, and -0.6 (-4.1 to 2.0) cm and 1.9 (-2.3 to 5.0) cm for the radiographs. For arm lengthening, correlation coefficient was good (r = 0.7) even though radiographs indicated arm shortening in five cases whereas arm lengthening was observed on CT scans. CONCLUSIONS: Measurements on radiographs and CT scans are comparable in most of the cases. However, we observed some important variations that question the reliability of radiographic measurements in up to 20 % of cases. Therefore, a CT scan appears to be necessary in the event of postoperative complications (e.g., instability, neurological problems).

Glenoid bone grafting in reverse shoulder arthroplasty for long-standing anterior shoulder dislocation.

BACKGROUND: Long-standing anterior glenohumeral dislocation results in both humeral and glenoid bone loss, as well as concomitant soft tissue pathologies. Reverse shoulder arthroplasty (RSA) is an established procedure to restore both stability and function in cuff-deficient shoulders. However, fixation of the glenoid component is prone to failure in cases of advanced glenoid vault destruction and requires substantial bone graft. The purpose of this study was to evaluate the outcome of glenoid bone grafting in RSA for neglected anterior dislocation with significant glenoid bone loss. MATERIALS AND METHODS: We reviewed 21 of 32 patients after 1-staged RSA and glenoid bone grafting with resected humeral head, with a mean follow-up period of 4.9 years (range, 2-10 years). The mean age at the time of surgery was 71 years (range, 50-85 years). Glenoid bone loss averaged 45% of glenoid width according to preoperative computed tomography or magnetic resonance imaging scans. A long-pegged glenoid baseplate was used in 9 patients. RESULTS: The mean Constant score improved from 5.7 points (range, 0-22 points) preoperatively to 57.2 points (range, 26-79 points) postoperatively (P < .001). Two patients required revision because of baseplate loosening: one patient underwent conversion to a hemiarthroplasty, and the other patient underwent a 2-staged reconstruction with tricortical iliac crest bone graft. CONCLUSION: RSA in neglected anterior dislocation is a successful treatment option even in the case of advanced glenoid bone loss. To maintain stable fixation of the glenoid component, comprehensive preoperative analysis of the remaining bone stock based on 3-dimensional computed tomography scans should be included, with particular attention to ensure optimal anchorage length of the baseplate's central peg in the native glenoid bone stock.

Revision to reverse shoulder arthroplasty with retention of the humeral component.

BACKGROUND: Revision in failed shoulder arthroplasty often requires removal of the humeral component with a significant risk of fracture and bone loss. Newer modular systems allow conversion from anatomic to reverse shoulder arthroplasty with retention of a well-fixed humeral stem. We report on a prospectively evaluated series of conversions from hemiarthroplasty to reverse shoulder arthroplasty. METHODS: In 14 cases of failed hemiarthroplasty due to rotator cuff deficiency and painful pseudoparalysis (in 13 women), revision to reverse shoulder arthroplasty was performed between October 2006 and 2010, with retention of the humeral component using modular systems. Mean age at the time of operation was 70 (56-80) years. Pre- and postoperative evaluation followed a standardized protocol including Constant score, range of motion, and radiographic analysis. Mean follow-up time was 2.5 (2-5.5) years. RESULTS: Mean Constant score improved from 9 (2-16) to 41 (17-74) points. Mean lengthening of the arm was 2.6 (0.9-4.7) cm without any neurological complications. One patient required revision due to infection. INTERPRETATION: Modular systems allow retainment of a well-fixed humeral stem with good outcome. There is a risk of excessive humeral lengthening.