Anterior deltoid deficiency in reverse total shoulder replacement

Spontaneous Deltoid Tear in Cuff Tear Arthropathy and Its Effect on the Outcome of Reverse Total Shoulder Arthroplasty: A Comparison Using Propensity Score Matching

Background

Deltoid function critically influences the results of reverse total shoulder arthroplasty (RTSA), and spontaneous deltoid attrition tears are frequently detected in cuff tear arthropathy (CTA) patients; however, the clinical impacts of these tears on RTSA outcomes are undetermined. Our aim was to determine the effect of spontaneous deltoid attrition tears on postoperative outcomes after RTSA without an additional deltoid procedure.

Methods

Seventy-two patients who underwent RTSA for CTA with preoperative magnetic resonance imaging (MRI) and a minimum clinical follow-up of 1 year (mean, 32 months) were retrospectively reviewed in the study. Patients with a history of previous shoulder surgery or injury were excluded. The presence and location of deltoid attrition tears were determined in preoperative MRI. Propensity score matching (1:1) was performed to construct tear and no-tear groups. Finally, 21 patients, matched with respect to age, sex, hand dominance, symptom duration, medical comorbidity (obesity, diabetes mellitus, and coronary artery disease), Hamada grade, and implant type, were assigned to each group. Clinical outcomes (functional scores, isometric power, and range of motion) in the two groups were compared.

Results

Deltoid attrition tears were detected in 21 of the 72 enrolled cases (29.1%). Anterolateral deltoid was the most frequent location and no tear was detected in the posterior deltoid. The tear rate increased with disease severity (Hamada G2, 4.8%; G3, 23.8%; > G4, 71.4%). No pre- or postoperative clinical variables differed significantly between the tear and no tear groups.

Conclusions

Deltoid attrition tears were detected in 29% of CTA patients who underwent RTSA. The most common site was the anterolateral region and tear prevalence tended to increase with CTA progression. However, RTSA was found to provide satisfactory outcomes regardless of the presence of a deltoid attrition tear.

Ex vivo experimental strategies for assessing unconstrained shoulder biomechanics: A scoping review

BACKGROUND

Biomechanical studies of the shoulder often choose an ex vivo approach, especially when investigating the active and passive contribution of individual muscles. Although various simulators of the glenohumeral joint and its muscles have been developed, to date a testing standard has not been established. The objective of this scoping review was to present an overview of methodological and experimental studies describing ex vivo simulators that assess unconstrained, muscular driven shoulder biomechanics.

METHODS

All studies with ex vivo or mechanical simulation experiments using an unconstrained glenohumeral joint simulator and active components mimicking the muscles were included in this scoping review. Static experiments and humeral motion imposed through an external guide, e.g., a robotic device, were excluded.

RESULTS

Nine different glenohumeral simulators were identified in 51 studies after the screening process. We identified four control strategies characterized by: (a) using a primary loader to determine the secondary loaders with constant force ratios; (b) using variable muscle force ratios according to electromyography; (c) calibrating the muscle path profile and control each motor according to this profile; or (d) using muscle optimization.

CONCLUSION

The simulators with the control strategy (b) (n = 1) or (d) (n = 2) appear most promising due to its capability to mimic physiological muscle loads.

Open reduction and internal fixation of Ideberg type IA glenoid fractures: Tricks, pearls, and potential pitfalls based on a retrospective cohort of 33 patients focusing on the rehabilitation protocol

INTRODUCTION

The standard treatment of anterior glenaoid fractures carrying > 20% of the glenoid fossa is open reduction and internal fixation (ORIF). In the herein study, we report our outcomes in a retrospective cohort of anterior and anteroinferior glenoid rim fractures using an accelerated postoperative rehabilitation protocol. A secondary aim is to describe the surgical steps for ORIF of anterior and anteroinferior glenoid rim fractures using the anterior axillary approach, describing the tricks, pearls, and pitfalls of this surgical technique.

METHODS

A retrospective cohort of skeletally mature patients treated for an anterior glenoid rim fracture carrying > 20% of the glenoid fossa during a 10-year period were operated on using a vertical axillary incision, osteosynthesis with 2.0-mm cortical screws, and labral repair with small diameter metallic anchors and non-absorbable sutures. Rehabilitation began on the first postoperative day, including passive external rotation exercises and active-assisted flexion, adduction, and abduction exercises as tolerated. The exercises are performed with the patient sitting or lying down. Phase 1 is continued for 6-10 weeks until the patient regains painless, normal, or near-normal ROM. Usually by 10 weeks, the fracture and labrum are healed, so phase 2 rehabilitation begins with strengthening and ROM exercises. Radiologic and clinical outcomes, including active range of motion (ROM), glenohumeral stability, and visual analogue scale (VAS) were measured.

RESULTS

About 33 patients (35 fractures) had complete medical records and pre- and post-operative imaging exams available for further analysis regarding the surgical protocol, with a mean of 4.8 years. The mean DASH questionnaire was 3.75 ± 9.0 and the mean CM score was 62.5 ± 0.1. Active flexion and internal rotation were recovered in all patients, while external rotation presented an average loss of 8° (p = 0.12) and abduction of 5° (p = 0.33). The mean VAS was 1.1 ± 0.8. No patient reported major or disabling symptoms, or great difficulty or inability to perform daily or recreational activities. No patient presented residual instability of the glenohumeral joint.

CONCLUSION

In this retrospective cohort, ORIF using a vertical axillary incision, osteosynthesis with 2.0-mm screws, and labral repair with small diameter metallic anchors and non-absorbable sutures was a safe approach, with a minimal risk of complications and residual instability. The accelerated postoperative rehabilitation protocol, allowing immediate passive external rotation of the operated shoulder, resulted in a non-significant loss of ROM compared to the contralateral side. Therefore, we recommend this management strategy for anterior glenoid rim fractures in patients with unstable shoulder joint after traumatic glenohumeral dislocation.

LEVEL OF EVIDENCE IV

Therapeutic Study (Surgical technique and Retrospective cohort).

Biomechanics of anatomic and reverse shoulder arthroplasty

The biomechanics of the shoulder relies on careful balancing between stability and mobility. A thorough understanding of normal and degenerative shoulder anatomy is necessary, as the goal of anatomic total shoulder arthroplasty is to reproduce premorbid shoulder kinematics.With reported joint reaction forces up to 2.4 times bodyweight, failure to restore anatomy and therefore provide a stable fulcrum will result in early implant failure secondary to glenoid loosening.The high variability of proximal humeral anatomy can be addressed with modular stems or stemless humeral components. The development of three-dimensional planning has led to a better understanding of the complex nature of glenoid bone deformity in eccentric osteoarthritis.The treatment of cuff tear arthropathy patients was revolutionized by the arrival of Grammont's reverse shoulder arthroplasty. The initial design medialized the centre of rotation and distalized the humerus, allowing up to a 42% increase in the deltoid moment arm.More modern reverse designs have maintained the element of restored stability but sought a more anatomic postoperative position to minimize complications and maximize rotational range of motion. Cite this article: EFORT Open Rev 2021;6:918-931. DOI: 10.1302/2058-5241.6.210014.

Reverse shoulder-allograft prosthesis composite, with or without tendon transfer, for the treatment of severe proximal humeral bone loss

BACKGROUND

The treatment of severe proximal humeral bone loss (PHBL) secondary to tumor resection or failed arthroplasty is challenging. We evaluated the outcomes and complications of reconstruction with reverse shoulder-allograft prosthesis composite (RS-APC), performed with or without tendon transfer.

METHODS

An RS-APC procedure was performed in 25 consecutive patients with severe PHBL (>4 cm): 12 after failed reverse shoulder arthroplasty, 5 after failed hemiarthroplasty for fracture, 6 after failed mega-tumor prosthesis placement, and 2 after tumor resection. The median length of humeral bone loss or resection was 8 cm (range, 5-23 cm). Humeral bone graft fixation was obtained with a long monobloc reverse stem and a "mirror step-cut osteotomy," without plate fixation. Nine infected shoulders underwent a 2-stage operation with a temporary cement spacer. In addition, 9 patients (36%) underwent an associated L'Episcopo procedure. The median follow-up duration was 4 years (range, 2-11 years).

RESULTS

Overall, 76% of patients (19 of 25) were satisfied. In 8 patients (32%), a reoperation was needed. At last follow-up, we observed incorporation at the allograft-host junction in 96% of the cases (24/25); partial graft resorption occurred in 3 cases and severe in 1. The median adjusted Constant score was 53% (range 18-105); Subjective Shoulder Value, 50% (range 10%-95%). Additional tendon transfers significantly improved active external rotation (20° vs. 0°, P < .001) and forward elevation (140° vs. 90°, P = .045).

CONCLUSIONS

(1) Shoulder reconstruction with RS-APC provides acceptable shoulder function and high rates of graft survival and healing. (2) Additional L'Episcopo tendon transfer (when technically possible) improves active shoulder motion. (3) The use of a long monobloc (cemented or uncemented) humeral reverse stem with mirror step-cut osteotomy provides a high rate of graft-host healing, as well as a limited rate of graft resorption, and precludes the need for additional plate fixation. (4) Although rewarding, this reconstructive surgery is complex with a high risk of complications and reoperations. The main advantages of using an allograft with a reverse shoulder arthroplasty (compared with other reconstruction options) are that this type of reconstruction (1) allows restoration of the bone stock, thus improving prosthesis fixation and stability, and (2) gives the possibility to perform a tendon transfer by fixing the tendons on the bone graft to improve shoulder motion.

Subscapularis-On Approach in Reverse Shoulder Arthroplasty

Using a subscapularis- and deltoid-preserving anterior approach is an option for patients undergoing reverse shoulder arthroplasty. Outcomes are better at short term than compared with the standard deltopectoral approach. Maintaining the integrity of the subscapularis tendon and preserving the deltoid muscle minimizes the need for postoperative immobilization and rehabilitation, allowing the patient to achieve active shoulder range of motion more rapidly, without increasing the incidence of shoulder dislocation. Overall length of hospital stay and duration of postoperative physical therapy are minimized, leading to significant economic gain. Future studies with longer follow-up are required to document the potential long-term benefits of this surgical technique.

Level of Evidence of the study: Review, Level IV

Subscapularis- and deltoid-sparing vs traditional deltopectoral approach in reverse shoulder arthroplasty: a prospective case-control study

Background

With the growth of reverse shoulder arthroplasty (RSA), it is becoming increasingly necessary to establish the most cost-effective methods for the procedure. The surgical approach is one factor that may influence the cost and outcome of RSA. The purpose of this study was to compare the clinical results of a subscapularis- and deltoid-sparing (SSCS) approach to a traditional deltopectoral (TDP) approach for RSA. The hypothesis was that the SSCS approach would be associated with decreased length of stay (LOS), equal complication rate, and better short-term outcomes compared to the TDP approach.

Methods

A prospective evaluation was performed on patients undergoing RSA over a 2-year period. A deltopectoral incision was used followed by either an SSCS approach or a traditional tenotomy of the subscapularis (TDP). LOS, adverse events, physical therapy utilization, and patient satisfaction were collected in the 12 months following RSA.

Results

LOS was shorter with the SSCS approach compared to the TDP approach (from 8.2 ± 6.4 days to 15.2 ± 11.9 days; P = 0.04). At 3 months postoperative, the single assessment numeric evaluation score (80 ± 11% vs 70 ± 6%; P = 0.04) and active elevation (130 ± 22° vs 109 ± 24°; P = 0.01) were higher in the SSCS group. The SSCS approach resulted in a net cost savings of $5900 per patient. Postoperative physical therapy, pain levels, and patient satisfaction were comparable in both groups. No immediate intraoperative complications were noted.

Conclusion

Using a SSCS approach is an option for patients requiring RSA. Overall LOS is minimized compared to a TDP approach with subscapularis tenotomy. The SSCS approach may provide substantial healthcare cost savings, without increasing complication rate or decreasing patient satisfaction.

Massive irreparable rotator cuff tear and associated deltoid tear. Does the reverse shoulder arthroplasty and deltoid repair be a possible option of treatment?

BACKGROUND AND PURPOSE

Rupture of the anterior and middle deltoid muscle associated with rotator cuff tear arthropathy (RCA) could result in a definitive loss of shoulder function. The purpose of this study was to evaluate clinical outcomes after a concomitant reverse shoulder arthroplasty (RSA) and deltoid repair under these circumstances.

MATERIALS AND METHODS

Between 2006 and 2012, 18 consecutive patients with a mean age of 69.7 years, affected by massive irreparable rotator cuff tear and associated dehiscence or rupture of anterior and middle deltoid muscle underwent this operation through a modified anterosuperior approach. Four patients referred a previous shoulder surgery and deltoid tear was iatrogenic. The other 14 cases had an attritional deltoid tears. The average follow-up was 64 months (range 25-121 months).

RESULTS

The mean active anterior elevation passed from a preoperative mean of 53 ± 9.1 (range 45-70) to 132.7 ± 11.6° (85-155°), active external rotation passed from a preoperative mean value of 22.4 ± 3.6° (range 18-26) to an average of 33.7 ± 4.7° (range 30-40°). Mean Constant score increased from 42 ± 6.1 (range 31-51) pre-operatively to 72.3 ± 8.2 (range 57-82) post-operatively. At final review, deltoid contour subjectively was satisfactory to all patients with no palpable defects.

CONCLUSION

RSA associated with a repair of deltoid tear could be a viable surgical option in cases of tear involving the anterior and middle deltoid associated with a RCA. Patient with a preoperative chronic axillary nerve neuropathy associated with a deltoid muscle tear should be cautioned about the possibility of lower functional outcomes.

Reverse total shoulder arthroplasty with combined deltoid reconstruction in patients with anterior and/or middle deltoid tears

BACKGROUND AND HYPOTHESIS

Deltoid disruption has traditionally been an absolute contraindication to performing a reverse total shoulder arthroplasty (RTSA), and options available to patients have been limited. We present a series of patients with deltoid tears that underwent concomitant RTSA with deltoid reconstruction. We hypothesize that this combined procedure provides an acceptable, functional alternative for this complex patient population.

MATERIALS AND METHODS

We retrospectively identified all patients who were treated by a single surgeon with a concomitant RTSA and deltoid reconstruction from 2004 to 2012 with minimum 24-month follow-up. Six shoulders in 5 patients met these criteria. The mean age was 69 years (range, 61-79 years), and the mean follow-up period was 76.8 months (range, 24-133 months). We compared preoperative and postoperative range of motion and Penn Shoulder Scores, including subscores, using paired t tests.

RESULTS

Mean forward elevation and external rotation increased from 48° and 12°, respectively, to 120° and 22°, respectively. Penn scores increased from 45.2 to 77.8 postoperatively (P = .03). The Penn satisfaction subscore, in particular, improved from 1.1 (of 10) to 9.0 (P = .005). There was a low rate of recurrent deltoid failure (1 of 6 shoulders), and there were no infections or revisions.

DISCUSSION

Deltoid reconstruction at the same time as RTSA is a viable treatment option as a salvage procedure for patients with deltoid deficiency who otherwise need RTSA for treatment of massive rotator cuff deficiency. In this small series, simultaneous RTSA and deltoid reconstruction resulted in a functional shoulder with a high level of satisfaction and good motion.

LEVEL OF EVIDENCE

Level IV; Case Series; Treatment Study.

Allograft-prosthetic composite reverse total shoulder arthroplasty for reconstruction of proximal humerus tumor resections

BACKGROUND

Proximal humerus reconstructions after resection of tumors are challenging. Early success of the reverse shoulder arthroplasty for reconstructions has recently been reported. The reverse allograft-prosthetic composite offers the advantage of improved glenohumeral stability compared with hemiarthroplasty for proximal humeral reconstructions as it uses the deltoid for stability.

METHODS

This article describes the technique for treating proximal humeral tumors, including preoperative planning, biopsy principles, resection pearls, soft tissue tensioning, and specifics about reconstruction using the reverse allograft-prosthetic composite. Two cases are presented along with the functional outcomes with use of this technique. Biomechanical considerations during reconstruction are reviewed, including techniques to improve the deltoid compression force.

RESULTS

Reported instability rates are less with reverse shoulder arthroplasty reconstruction as opposed to hemiarthroplasty or total shoulder arthroplasty reconstructions of tumor resections. Reported functional outcomes are promising for the reverse allograft-prosthetic composite reconstructions, although complications are reported.

CONCLUSION

Reverse allograft-prosthetic composites are a promising option for proximal humeral reconstructions, although nonunion of the allograft-host bone junction continues to be a challenge for this technique.

The effects of progressive lateralization of the joint center of rotation of reverse total shoulder implants

BACKGROUND

There has been a renewed interest in lateralizing the center of rotation (CoR) in implants used in reverse shoulder arthroplasty. The aim of this study was to determine the sensitivity of lateralization of the CoR on the glenohumeral joint contact forces, muscle moment arms, torque across the bone-implant interface, and the stability of the implant.

METHODS

A 3-dimensional virtual model was used to investigate how lateralization affects deltoid muscle moment arm and glenohumeral joint contact forces. This model was virtually implanted with 5 progressively lateralized reverse shoulder prostheses. The joint contact loads and deltoid moment arms were calculated for each lateralization over the course of 3 simulated standard humerothoracic motions.

RESULTS

Lateralization of the CoR leads to an increase in the overall joint contact forces across the glenosphere. Most of this increased loading occurred through compression, although increases in anterior/posterior and superior/inferior shear were also observed. Moment arms of the deltoid consistently decreased with lateralization. Bending moments at the implant interface increased with lateralization. Progressive lateralization resulted in improved stability ratios.

CONCLUSIONS

Lateralization results in increased joint loading. Most of that loading occurs through compression, although there were also increases in shear forces. Anterior/posterior shear is currently not accounted for in implant fixation studies, leaving its effect on implant fixation unknown. Future studies should incorporate shear forces into their models to more accurately assess fixation methods.

Reverse total shoulder arthroplasty: a biomechanical evaluation of humeral and glenosphere hardware configuration

BACKGROUND

Various reverse total shoulder arthroplasty (rTSA) implant options are available for the humeral and glenosphere components. This study used a cadaveric biomechanical shoulder simulator to evaluate how hardware configurations in 2 common rTSA systems affect (1) abduction/adduction range of motion (ROM), (2) rotational ROM, and (3) forces to elevate the arm.

METHODS

Seven pairs of shoulders were tested on a biomechanical shoulder simulator before and after rTSA implantation. The Aequalis Reverse Shoulder (Tornier, Edina, MN, USA) and the Reverse Shoulder Prosthesis (RSP; DJO Surgical, Austin, TX, USA) were implanted in opposing shoulders. Aequalis implant options included humeral polymer insert thickness and eccentricity and glenosphere tilt. RSP implant options included glenosphere diameter and lateralization, humeral shell offset, and polymer insert depth.

RESULTS

Both the RSP and Aequalis shifted the center of rotation inferior and medially compared with native shoulders (P < .001). Increased Aequalis insert thickness reduced adduction (P < .003) and internal/external (P < .028) passive ROM. The 10° inferiorly tilted glenosphere increased deltoid abduction forces (P < .032). In the RSP, smaller glenosphere diameter (P < .012), a semiconstrained humeral insert (P < .023), and a neutral humeral shell offset (P < .002) all decreased adduction deficit, whereas lateral glenosphere offset increased passive abduction ROM (P < .028). Increased humeral shell offset decreased passive internal/external rotation ROM (P < .050).

DISCUSSION

Hardware configurations in rTSA have different effects on passive ROM and deltoid forces required for abduction. Identifying these changes may guide surgical decision making during rTSA placement.

Biomechanics of reverse total shoulder arthroplasty

Reverse total shoulder arthroplasty is an effective procedure for treatment of glenohumeral joint disease among patients with severe rotator cuff deficiency. Improvements in prosthetic design are the result of an evolved understanding of both shoulder and joint replacement biomechanics. Although modern generations of the reverse shoulder prosthesis vary in specific design details, they continue to adhere to Grammont's core principles demonstrated by his original Delta III prosthesis. This review article discusses the biomechanics of reverse total shoulder arthroplasty with a focus on elements of implant design and surgical technique that may affect stability, postoperative complications, and functional outcomes.

Bulk effect of the deltoid muscle on the glenohumeral joint

Background

There remains controversy on the role of the deltoid on glenohumeral translations during basic and pitching motions. We thus studied the passive effect of the deltoid on the deltoid glenohumeral joint center (GHJC).

Methods

Six shoulders were tested using an automated mechanical system. A baseline motion pattern of the intact specimen was contrasted with glenohumeral translation after removal of the deltoid. Each condition was evaluated in abduction (ABD) and an abbreviated throwing motion (ATM) using retro-reflective, bone-embedded markers. The absolute trajectory and the area under the curve (AUC) for each motion were calculated and glenohumeral kinematics with respect to the GH translation were compared.

Results

The removal of the deltoid resulted in significant changes of the GH translation. During 30-60° of ABD, it resulted in a superior and more anterior GH translation, while in the 60-90° segment in a more inferior and medial GH translation. During 90-120°, the GH translation was medialized. In the pitching motion from maximum external rotation to 90° of external rotation (ER), the removal of the deltoid resulted in a more superior, anterior and lateral GH translation. Thus limits anterior translation in the abduction-external rotation position. In the remaining segments (90-80° and 80-45° of ER), it resulted in a lateralization of the GH translation.

Conclusions

Modelling the throwing shoulder, the deltoid has a significant influence on glenohumeral motion. Athletes with deltoid dysfunction and limited range of motion are at risk for injury due to the resulting change in their throwing mechanics.