Optimizing stability and motion in reverse shoulder arthroplasty with a 135° neck-shaft-angle: a computer model study of standard versus retentive humeral inserts.

Background: There has been a trend to shift from a 155° and 145° neck-shaft-angle (NSA) to a more "anatomical" reverse shoulder arthroplasty with less distalization and a 135° NSA. Multiple studies have shown that a 135° NSA is beneficial for motion. There are some concerns about primary implant stability with a 135° NSA. When instability is detected, increasing the tension with thicker inlays or changing the NSA to 145° are possible solutions. A retentive 135° (Ret135) inlay may be an alternative to avoiding increased distalization; however, retentive liners are widely regarded as salvage options reducing range of motion (ROM) and avoided by most surgeons. The hypothesis of this study was that a retentive 135° insert of the tested implant system may not have drawbacks for impingement-free ROM compared to a standard 145° insert (Sta145). Methods: In this computer model study, 22 computed tomographic scans (11 males/11 females) were used to create models with a constant humeral stem (Perform/Stryker) and +3 mm lateralized baseplate +36 mm glenosphere for females and +6 mm lateralized baseplate +39 mm glenosphere for males using Blueprint software (Imascap, Brest, France). A Ret135, standard 135° (Sta135), and Sta145 (+10°) insert were compared for adduction (ADD), extension (EXT), external rotation (ER), and internal rotation (IR) all with the arm at the side as well as for combined IR (CIR = EXT + IR) and combined notching relevant (CNR) ROM (EXT + ER + IR + ADD). Results: Sta135 showed significantly better ROM for ER, IR, ADD, EXT, CNR ROM, and CIR compared to Ret135 (P < .05) and significantly better EXT and ADD compared to Sta145 (P < .0001). Comparison of Ret135 and Sta145 showed equivalent ROM performance, which was slightly better but nonsignificant for ADD (P = .16), EXT (P = .31), CNR ROM (P = .7), and CIR (P = .54) in favor of Ret135. Isolated IR (P = .39) and ER (P = .32) were slightly better but nonsignificant in favor of a Sta145. Conclusion: For this implant system tested in a computer model, a 135° standard liner offers the best ROM. A 135° retentive liner maintains at least equivalent CIR and motion to prevent notching compared to a standard 145° liner. 135° retentive liners are more than salvage options and may help to prevent distalization and overtensioning by increased liner thickness.

Humeral head size predicts baseplate lateralization in reverse shoulder arthroplasty: a comparative computer model study.

Background: In reverse shoulder arthroplasty (RSA), the ideal combination of baseplate lateralization (BL), glenosphere size (GS), and glenosphere overhang (GOH) with a commonly used 145° neck shaft angle (NSA) is unclear. This is the first study evaluating correlations of body height (BH), humeral head size (HS), glenoid height (GH), and association of gender with best glenoid configurations for range of motion (ROM) maintaining anatomic lateralization (aLAT) for optimized muscle length in 145° and less distalized 135° RSA. Methods: In this computer model study, 22 computed tomographies without joint narrowing were analyzed (11 male/female). A standardized semi-inlay 145° platform stem was combined with 20 glenoid configurations (baseplate [B] 25, 25 + 3/+6 lateralized [l], 29, 29 + 3/6l combined with glenosphere 36, 36 + 2 eccentric [e], 36 + 3l, 39, 39 + 3e, 39 + 3l , 42, 42 + 4e). Abduction-adduction, flexion-extension, external rotation-internal rotation, total ROM (TROM), and total notching relevant (TNR) ROM were computed, best TROM models respecting aLAT (-1 mm to +1 mm) and HS/GH recorded. Second, the 145° models (Ascend Flex stem; Stryker, Kalamazoo, MI, USA) were converted and compared to a 135° inlay RSA (New Perform stem; Stryker, Kalamazoo, MI, USA) maintaining GOH (6.5-7 mm) and aLAT. Results: Best 145° models had eccentric glenospheres (mean BL: 3.5 mm, GOH 8.8 mm, GS 38.1 mm, distalization 23 mm). The 135° models had concentric glenospheres, mean BL 3.8 mm, GOH 6.9 mm, GS 39.7 mm, and distalization 14.1 mm. HS showed the strongest positive correlation with BL in 145° and 135° models (0.65/0.79). Despite reduced GOH in smaller females with a 135° NSA, adduction, external rotation, extension, TNR ROM, and TROM were significantly increased (P = .02, P = .005, P = .005, P = .004, P = .003), abduction however reduced (P = .02). The same trends were seen for males. Conclusion: HS is a practical measure in surgery or preoperatively, and the strong positive correlation with BL is a useful planning aid. Despite reduction of GOH, conversion to a less distalized 135° NSAinlay design is powerful to maintain and even significantly increase all components of TNR ROM (extension/external rotation/adduction) in small females with the drawback of reduced abduction which may however be compensated by scapula motion. Lateralization with a less distalized 135° RSA optimizes muscle length, may facilitate subscapularis repair, and maintains highest rigid body motion.

Correction: Bauer et al. Challenges for Optimization of Reverse Shoulder Arthroplasty Part II: Subacromial Space, Scapular Posture, Moment Arms and Muscle Tensioning. J. Clin. Med. 2023, 12, 1616.

In the original publication [...].

Challenges for Optimization of Reverse Shoulder Arthroplasty Part I: External Rotation, Extension and Internal Rotation.

A detailed overview of the basic science and clinical literature reporting on the challenges for the optimization of reverse shoulder arthroplasty (RSA) is presented in two review articles. Part I looks at (I) external rotation and extension, (II) internal rotation and the analysis and discussion of the interplay of different factors influencing these challenges. In part II, we focus on (III) the conservation of sufficient subacromial and coracohumeral space, (IV) scapular posture and (V) moment arms and muscle tensioning. There is a need to define the criteria and algorithms for planning and execution of optimized, balanced RSA to improve the range of motion, function and longevity whilst minimizing complications. For an optimized RSA with the highest function, it is important not to overlook any of these challenges. This summary may be used as an aide memoire for RSA planning.

Challenges for Optimization of Reverse Shoulder Arthroplasty Part II: Subacromial Space, Scapular Posture, Moment Arms and Muscle Tensioning.

In part II of this comprehensive review on the optimization of reverse shoulder arthroplasty (RSA), we focus on three other challenges: 1. "Conservation of sufficient subacromial and coracohumeral space"; 2. "Scapular posture"; and 3. "Moment arms and muscle tensioning". This paper follows a detailed review of the basic science and clinical literature of the challenges in part I: 1. "External rotation and extension" and 2. "Internal rotation". "Conservation of sufficient subacromial and coracohumeral space" and "Scapular posture" may have a significant impact on the passive and active function of RSA. Understanding the implications of "Moment arms and muscle tensioning" is essential to optimize active force generation and RSA performance. An awareness and understanding of the challenges of the optimization of RSA help surgeons prevent complications and improve RSA function and raise further research questions for ongoing study.

Computer navigation of the glenoid component in reverse total shoulder arthroplasty: a clinical trial to evaluate the learning curve.

BACKGROUND: Intraoperative computer navigation has been introduced recently to assist with placement of the glenoid component. The aim of this study was to evaluate the learning curve of a single surgeon performing computer navigation of glenoid implant placement in primary reverse total shoulder arthroplasty (RTSA). METHODS: Following training with the intraoperative computer navigation system, we conducted a prospective case-series study of the first 24 consecutive patients undergoing a primary RTSA with navigation performed by a single surgeon. Surgical times, complications, and accuracy of glenoid positioning compared with the preoperative plan were evaluated. Surgical times were compared with the preceding non-navigated series of 24 consecutive primary RTSA cases. Postoperative 3-dimensional computed tomography scans were performed to evaluate glenoid component version and inclination compared with the preoperative plan. RESULTS: The total surgical time was 77.3 minutes (standard deviation [SD], 11.8 minutes) in the navigated RTSA cohort and 78.5 minutes (SD, 18.1 minutes) in the non-navigated series. A significant downward trend in the total surgical time was observed in the navigated cohort (P = .038), which flattened after 8 cases. No learning curve was observed in deviation of glenoid version or inclination from the preoperative plan. The mean deviation of achieved version from planned version was 3° (SD, 2°), and the mean deviation of achieved inclination from planned inclination was 5° (SD, 3°). CONCLUSION: Findings from this study suggest that intraoperative computer navigation will not require substantially increased operating times compared with standard surgical techniques. With prior surgeon training, approximately 8 operative cases are required to achieve proficiency in intraoperative computer navigation of the glenoid component.

Activity following reverse total shoulder arthroplasty: What should surgeons be advising?

BACKGROUND: Reverse total shoulder arthroplasty (RTSA) is now the most frequently performed form of shoulder arthroplasty. There is currently no consensus on recommended levels of activity and sport following RTSA. The aim of this review is to outline the current evidence and provide a guide for surgeons on what to advise their patients regarding activity level following RTSA. METHODS: A systematic review of the literature was performed using the Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search was performed using the electronic databases PubMed and Medline. Included studies were of level 1 to 4 evidence in the English language evaluating complications and return to sport after RTSA. RESULTS: Eleven studies were selected and included a total of 621 patients (67% female) with a mean age of 73 years (range 22-92). All of the included patients participated in sports prior to RTSA. The rate of return to sport ranged from 60 to 86% and varied with the level of sport activity. Mean time to return to sport after surgery varied greatly between studies. CONCLUSIONS: Return to sport is tolerated following RTSA; however, studies are short to medium term only and although the reported complication rate is low, the studies did not include radiographic evaluation. Longer term studies with subgroup analysis evaluating common recreational activities after RTSA are required, particularly in the younger population, in order to establish clear post-operative guidelines.

Autologous tenocyte implantation, a novel treatment for partial-thickness rotator cuff tear and tendinopathy in an elite athlete.

Tendinopathy and small partial-thickness tears of the rotator cuff tendon are common presentations in sports medicine. No promising treatment has yet been established. Corticosteroid injections may improve symptoms in the short term but do not primarily treat the tendon pathology. Ultrasound-guided autologous tenocyte implantation (ATI) is a novel bioengineered treatment approach for treating tendinopathy. We report the first clinical case of ATI in a 20-year-old elite gymnast with a rotator cuff tendon injury. The patient presented with 12 months of increasing pain during gymnastics being unable to perform most skills. At 1 year after ATI the patient reported substantial improvement of clinical symptoms. Pretreatment and follow-up MRIs were reported and scored independently by two experienced musculoskeletal radiologists. Tendinopathy was improved and the partial-thickness tear healed on 3 T MRI. The patient was able to return to national-level competition.

Fractional lengthening of forearm extensors for resistant lateral epicondylitis.

BACKGROUND: This study presents the surgical technique of fractional lengthening of extensor carpi radialis brevis, extensor digitorum communis and the superficial head of supinator, for chronic lateral epicondylitis. The anatomical basis for this surgical approach is reviewed. The results of surgical treatment in a consecutive series of patients with severe chronic lateral epicondylitis are reviewed. METHODS: Twenty-one elbows in 17 subjects underwent surgery. All elbows had severe resistant symptoms, unresponsive to a minimum 6 months (mean 14 months) of a non-operative treatment protocol. All elbows showed either tendonopathy or a partial tear in the common extensor tendon origin at preoperative imaging. RESULTS: All subjects were examined at a minimum of 1 year after surgery. The mean visual analogue pain (VAS) score reduced from 7.6 (maximum 10) preoperatively to 1.3 postoperatively (P<0.01). The mean preoperative ability to carry out normal work duties reduced from 4.3 (maximum 5) preoperatively to 1.5 postoperatively (P<0.01). Grip strength improved or remained equivalent following surgery. The mean VAS for patient satisfaction with surgery was 8.8 (maximum score 10). Using the Roles and Maudsley classification, 14 patients (82%) were rated good or excellent. Three subjects were rated fair or poor, were undergoing treatment for other pathology in the ipsilateral extremity and had ongoing compensation claims. CONCLUSION: Fractional lengthening of forearm extensors is effective treatment for severe and chronic lateral epicondylitis. Outcomes following fractional lengthening surgery are less predictable when other pathology in the upper extremity requires concomitant treatment.

Exercise improves early functional recovery after total hip arthroplasty.

The purpose of this prospective, randomized study was to apply an 8-week customized exercise program to patients (Group E) scheduled for total hip arthroplasty, followed by a postsurgery exercise program, and show the effect on functional recovery compared with control subjects (Group C) who received no additional exercise apart from routine in-hospital physical therapy. Strength, range of motion, and physical function tests were completed by 57 patients at Week 8 and Week 1 before surgery and at Weeks 3, 12, and 24 postoperatively. No differences between the exercise and control groups were observed at baseline. By 1 week before surgery, patients in Group E had shown significant improvements for Western Ontario and McMaster Universities Osteoarthritis Index (total score, stiffness, and physical function components), and combined hip strength. Patients in Group E had improved hip flexion range of motion in the diseased hip compared with patients in Group C. Significant differences in outcome measures between Group E and Group C were observed throughout the postoperative phase from Weeks 3 to 24. The current study showed that customized perioperative exercise programs are well tolerated by patients with end-stage hip arthritis, and are effective in improving early recovery of physical function after total hip arthroplasty.

Perioperative exercise programs improve early return of ambulatory function after total hip arthroplasty: a randomized, controlled trial.

OBJECTIVE: Patients with endstage hip arthritis have poor ambulatory function. The aim of this study was to determine if perioperative exercise programs are well tolerated by these elderly patients and if a customized program can achieve an earlier recovery of normal ambulatory function after total hip arthroplasty. DESIGN: Twenty-eight subjects scheduled for total hip arthroplasty were randomized to either the exercise group and received a perioperative customized exercise program or the control group and received the routine perioperative care. Ambulatory function was assessed by measurement of gait parameters during a 25-m walk test, and walking endurance was assessed by a 6-min walk test. RESULTS: Exercise group subjects attended 97.3% of scheduled exercise sessions with no training injuries. Exercise group subjects demonstrated greater stride length and gait velocity at 3 wk postsurgery. At 12 and 24 wk postsurgery, gait velocity was greater, and the 6-min walking distance was significantly greater than the control group. CONCLUSION: The study indicates that perioperative customized exercise program are well tolerated in the elderly patient with endstage hip arthritis and are effective in improving the rate of recovery in ambulatory function in the first 6 mo after total hip arthroplasty.