Acceptable Long-Term Outcomes of Arthroscopic Bone Grafting for Recurrent Posterior Shoulder Instability: Minimum Follow-Up of 5 Years

Arthroscopic Posterior Bone Block Stabilization Using a Tricortical Autograft of the Ipsilateral Scapular Spine

Posterior bone grafting represents an emerging therapeutic approach for addressing recurrent instability in the posterior shoulder, particularly when coupled with substantial glenoid bone loss. Although not as prevalent as anterior instability, recent years have witnessed the development of numerous open and arthroscopic bony reconstruction methods. A technical gold standard for posterior bone grafting remains undefined, leading to ongoing advancements in bone grafting techniques. In response to past challenges associated with screw fixation, metal-free arthroscopic fixation procedures have been introduced to the realm of bone grafting. These metal-free methods often entail intricate transglenoid drilling, which poses potential surgical complexities and risks to both posterior and anterior soft tissues, as well as neurovascular structures. Therefore, we introduce an arthroscopic approach to posterior bone grafting using PEEK (polyether ether ketone) anchors with interconnected sutures and a scapular spine autograft. This method overcomes previous hurdles by facilitating the restoration of the posterior glenoid bone stock with precise positioning and secure fixation of the tricortical scapular spine bone autograft.

Posterior Shoulder Instability and Glenoid Bone Loss: A Review and a Free Bone Graft Technique

Posterior glenoid bone loss (pGBL) is frequently associated with posterior shoulder instability. Posterior glenohumeral instability accounts for a small percentage of shoulder pathologies, and critical bone loss in posterior instability has not been well defined in the literature. Younger patient populations who participate in activities that repetitively stress the posterior stabilizing structures of the shoulder are more prone to developing posterior shoulder instability. A variety of surgical options have been described, ranging from isolated capsulolabral repair to glenoid osteotomy. Soft-tissue repair alone may be an inadequate treatment in cases of pGBL and places patients at a high risk of recurrence. Our preferred technique for posterior glenoid reconstruction in cases of pGBL involves the transfer of a free iliac crest bone graft onto the native glenoid. The graft is contoured to fit the osseous defect and secured to provide an extension of the glenoid track. In this study, we review pGBL in the setting of posterior instability and describe our technique in detail. Further long-term studies are needed to refine the indications for glenoid bone graft procedures and quantify what constitutes a critical pGBL.

Posterior stability of the shoulder depends on acromial anatomy: a biomechanical study of 3D surface models

PURPOSE

Primary glenohumeral osteoarthritis is commonly associated with static posterior subluxation of the humeral head. Scapulae with static/dynamic posterior instability feature a superiorly and horizontally oriented acromion. We investigated whether the acromion acts as a restraint to posterior humeral translation.

METHODS

Five three-dimensional (3D) printed scapula models were biomechanically tested. A statistical shape mean model (SSMM) of the normal scapula of 40 asymptomatic shoulders was fabricated. Next, a SSMM of scapular anatomy associated with posterior subluxation was generated using data of 20 scapulae ("B1"). This model was then used to generate three models of surgical correction: glenoid version, acromial orientation, and acromial and glenoid orientation. With the joint axially loaded (100N) and the humerus stabilized, an anterior translation force was applied to the scapula in 35°, 60° and 75° of glenohumeral flexion. Translation (mm) was measured.

RESULTS

In the normal scapula, the humerus translates significantly less to contact with the acromion compared to all other configurations (p < .000 for all comparisons; i.e. 35°: "normal" 8,1 mm (± 0,0) versus "B1" 11,9 mm (± 0,0) versus "B1 Acromion Correction" 12,2 mm (± 0,2) versus "B1 Glenoid Correction" 13,3 mm (± 0,1)). Restoration of normal translation was only achieved with correction of glenoid and acromial anatomy (i.e. 75°: "normal" 11 mm (± 0,8) versus "B1 Acromion Correction" 17,5 mm (± 0,1) versus "B1 Glenoid Correction" 19,7 mm (± 1,3) versus "B1 Glenoid + Acromion Correction" 11,5 mm (± 1,1)).

CONCLUSIONS

Persistence or recurrence of static/dynamic posterior instability after correction of glenoid version alone may be related to incomplete restoration of the intrinsic stability that is conferred by a normal acromial anatomy.

LEVEL OF EVIDENCE V

biomechanical study.

Correction of Static Posterior Shoulder Subluxation by Restoring Normal Scapular Anatomy Using Acromion and Glenoid Osteotomies: A Case Report

CASE

A 40-year-old man presented with progressive shoulder pain, associated with static posterior subluxation and mild eccentric glenohumeral osteoarthritis. Compared with a mean statistical shape model of a normal shoulder, the patient's acromion was abnormally high and horizontal, and the glenoid abnormally inclined inferiorly and minimally retroverted. Restoration of normal scapular anatomy using 3-dimensional planned acromial and glenoid osteotomies led to recentering of the joint and full shoulder function up to 24 months postoperatively.

CONCLUSION

The correction of associated acromial and glenoid malformation can revert early static posterior subluxation of the shoulder. Whether successful recentering prevents progression of osteoarthritis remains to be established.

Mid-term to long-term results of open posterior bone block grafting in recurrent posterior shoulder instability: a clinical and CT-based analysis

Background

There is little consensus on the best treatment after failed conservative management of recurrent posterior shoulder instability. The purpose of this study was to analyze our clinical and radiological mid-term to long-term results of an open, posterior bone block procedure for the treatment of recurrent posterior shoulder instability.

Methods

From 1999 to 2015, 14 patients were included in the study and available for clinical and radiographic follow-up (FU). FU included a standardized physical examination, assessment of the Constant-Murley-Score, subjective shoulder value, American Shoulder and Elbow Surgeons score, and Western Ontario Shoulder Instability Index. Conventional radiographs and a computed tomography (CT)-scan were performed preoperatively and at latest FU. Glenohumeral arthropathy was classified as per Samilson and Prieto. The CT scans were used to evaluate the structure of the graft (resorption, union), graft positioning, glenoid version, centering of the humeral head, and glenoid erosion and morphology.

Results

The median age at the time of surgery was 26 years (range 16-41 years) and the median FU period was 9 years (range 4-20 years). The rate of reported dynamic postoperative subluxation and instability was 46% (n = 6) and the rate of dynamic posterior instability during clinical testing at FU was 31% (n = 4). The tested instability rate in the traumatic group was 14% (n = 1) compared to the atraumatic group with 50% (n = 3) during clinical FU. The mean Constant-Murley-Score increased from preoperatively (77 ± 11 points) to postoperatively (83 ± 14 points, P = .158). The last FU showed an American Shoulder and Elbow Surgeons score of 85 ± 12; the Western Ontario Shoulder Instability Index score was 715 ± 475 points. The mean subjective shoulder value increased from 58% ± 19 preoperatively to 73% ± 17 at final FU (P = .005). Degenerative changes increased by at least one grade in 67% of the patients. Mean preoperative glenoid retroversion (CT) was 7.5° ± 6°. The position of the graft was optimal in 86% (n = 12). In 62% of the cases, a major resorption of the graft (Zhu grade II) was observed.

Conclusion

The rate of tested recurrent instability at last FU was as high as 31% (n = 4, atraumatic [n = 3] vs. traumatic [n = 1]) after a median FU of 9 years. Given the moderate improvement of clinical outcome scores, shoulder stability and the increase of degenerative joint changes by at least one grade (Samilson/Prieto) in 67% of patients, a posterior bone block procedure is not a uniformly satisfying treatment option for recurrent posterior shoulder subluxation, especially in cases of atraumatic posterior instability.

Arthroscopic Bone Block Procedure for Posterior Shoulder Instability: Updated Surgical Technique

Posterior shoulder instability is generally caused by traumatic posterior dislocations or repetitive microtrauma during sports or other activities and has an annual incidence rate of 4.64 per 100,000 person-years. Several surgical techniques to treat posterior shoulder instability have been described, including soft-tissue repair and both open and arthroscopic bone block procedures. However, even though patient-reported outcomes are commonly high, surgical procedures are associated with high complication and revision rates of up to 14% and 67%, respectively. In particular, accurate placement of the bone graft, screw orientation, and the treatment of concomitant lesions are considered challenging. Therefore, improvement of surgical techniques is desirable. This Technical Note describes an updated approach to the arthroscopic posterior bone block augmentation described by Lafosse et al. (2012), with tips and tricks on the harvest and positioning of the graft.

Comprehensive management of posterior shoulder instability: diagnosis, indications, and technique for arthroscopic bone block augmentation

Recurrent posterior glenohumeral instability is an entity that demands a high clinical suspicion and a detailed study for a correct approach and treatment. Its classification must consider its biomechanics, whether it is due to functional muscular imbalance or to structural changes, volition, and intentionality.

Due to its varied clinical presentations and different structural alterations, ranging from capsule-labral lesions and bone defects to glenoid dysplasia and retroversion, the different treatment alternatives available have historically had a high incidence of failure.

A detailed radiographic assessment, with both CT and MRI, with a precise assessment of glenoid and humeral bone defects and of glenoid morphology, is mandatory.

Physiotherapy focused on periscapular muscle reeducation and external rotator strengthening is always the first line of treatment. When conservative treatment fails, surgical treatment must be guided by the structural lesions present, ranging from soft tissue repair to posterior bone block techniques to restore or increase the articular surface.

Bone block procedures are indicated in cases of recurrent posterior instability after the failure of conservative treatment or soft tissue techniques, as well as symptomatic demonstrable nonintentional instability, presence of a posterior glenoid defect >10%, increased glenoid retroversion between 10 and 25°, and posterior rim dysplasia. Bone block fixation techniques that avoid screws and metal allow for satisfactory initial clinical results in a safe and reproducible way.

An algorithm for the approach and treatment of recurrent posterior glenohumeral instability is presented, as well as the author’s preferred surgical technique for arthroscopic posterior bone block.

Bone Block Augmentation of the Posterior Glenoid for Recurrent Posterior Shoulder Instability Is Associated With High Rates of Clinical Failure: A Systematic Review

PURPOSE

To determine whether posterior glenoid bone block augmentation performed for the treatment of recurrent posterior shoulder instability succeeds in restoring stability and is associated with rates of complications or clinical failures comparable to other glenoid bone augmentation procedures.

METHODS

A comprehensive search of PubMed, MEDLINE, and EMBASE databases was performed. Level of evidence studies I to IV pertaining to posterior bone block augmentation reporting on outcomes or complications were included. The search was carried out in accordance with the Preferred Reported Items for Systematic Reviews and Meta-analyses guidelines.

RESULTS

Screening of titles, abstracts, and manuscripts with application of inclusion and exclusion criteria yielded 17 full-text articles reporting on 269 shoulders undergoing bone block augmentation. Surgical technique varied between studies with regard to graft type (iliac crest, 13 studies; scapular spine, 2; acromion, 1; distal tibia allograft, 1), graft positioning (medial to 1.5 cm lateral to glenoid surface, equatorial to subequatorial), and open versus arthroscopic technique (open, 10 studies; arthroscopic, 4; both, 3). Four of the 8 studies with pre- and postoperative patient-reported outcomes (PROs) showed significant improvements in these outcomes at final follow-up. The postoperative outcomes ranged from 60 to 90 for Rowe scores (n = 7 studies) and 79 to 90 for Walch-Duplay scores (n = 7 studies). Complications were commonly encountered, with high rates of recurrent instability (0% to 73%) and revision procedures (0% to 67%) across different studies.

CONCLUSION

Posterior bone block augmentation for recurrent posterior shoulder instability does not reliably yield substantial improvements in PROs, and complications are frequently observed. The substantial heterogeneity across studies and the small number of patients precludes any substantive judgements as to the superiority of one surgical technique over another.

LEVEL OF EVIDENCE

IV, systematic review of level III and IV studies.

Proper Evaluation of Bone Loss Determines Shoulder Instability Indications and Outcomes

One of the most-read articles published in the history of Arthroscopy: The Journal of Arthroscopic and Related Surgery is "Evolving Concept of Bipolar Bone Loss and the Hill-Sachs Lesion: From 'Engaging/Non-Engaging' Lesion to 'On-Track/Off-Track' Lesion" by Di Giacomo, Itoi, and Burkhart. This 2014 article is a modern classic and has inspired a plethora of recent research as well as infographics published in Arthroscopy. We now understand, to the great benefit of patients, that proper evaluation of bone loss determines shoulder instability surgical indications and outcomes.