Volume 05 / Issue 01 / March 2017 boa.ac.uk Page 50 JTO Subspecialty Section Management of bone loss in shoulder instability Chu-Hao Chiang Co-Authors: Abhinav Gulihar & Nicholas Little Management Management of glenohumeral joint (GHJ) instability can be challenging in the presence of structural bone defects of the glenoid or humerus. The presence of glenoid or humeral bone loss has been shown to be an important factor in the failure of arthroscopic stabilisation of the GHJ 1. Therefore, it is important to recognise the presence of any bone defects prior to surgery in patients with instability. The average anterior/posterior dimensions of the glenoid is 24 to 26 millimetres. Therefore, even a minor bone defect of 6 to 8 millimetres represent about 25% glenoid bone loss 2. Lo et al. described the inverted pear shaped glenoid which is usually associated with a significant structural defect of greater than 30% 3. allow visualisation of the defect s size and location (Figure 1). Bone loss can also be measured intraoperatively (Figure 2) 3. Yamamoto et al. demonstrated through cadaveric biomechanical studies that glenoid bone loss of 25% led to significant instability 5,6. This figure has been confirmed by Burkhart et al. who noted a 67% failure rate of Bankart repairs in patients with greater than 25% glenoid bone loss, compared with 4% in those without bone loss 1. However, cadaveric studies have shown glenoid bone loss of 15% leads to instability 7. Consequently, Balg et al. suggested that young patients, with higher demands, would benefit from reconstruction of glenoid bone loss of 15% or more 4. We believe that bone loss of more than 20% should be reconstructed using autologous >> Chu-Hao Chiang Plain radiographs should include an antero-posterior view with the shoulder in internal rotation to demonstrate a Hill-Sachs lesion and a glenoid profile view to assess for anterior glenoid bone loss. The presence of a Hill-Sachs on an external rotation view usually indicates a large lesion 4. Computed Tomography (CT) scans with 3D construction Figure 1: Pre-operative CT scan demonstrating glenoid bone loss Figure 2: Intraoperative image from superior viewing portal demonstrating anterior glenoid bone loss
Volume 05 / Issue 01 / March 2017 boa.ac.uk Page 52 JTO Subspecialty Section A META-ANALYSIS COMPARING OPEN AND ARTHROSCOPIC LATARJET PROCEDURE FOUND THAT ALTHOUGH THEY BOTH PROVIDED A COMPARABLE CLINICAL OUTCOME WITH A LESS THAN 3.5% RECURRENCE RATE, THE ARTHROSCOPIC PROCEDURE WAS SIGNIFICANTLY MORE EXPENSIVE AS A RESULT OF THE LONGER OPERATION TIME AND THE USE OF ADDITIONAL EQUIPMENT. graft either tricortical (commonly from the iliac crest) or an ipsilateral coracoid transfer Bristow or Laterjet procedure (Figures 3 and 4). Although good results have been obtained with tricortical iliac crest, proponents of the Latarjet procedure argue that the dynamic sling provided by the conjoint tendon, combined with inferiorisation of the subscapularis muscle provides additional stability 8,9. Young et al. published the largest Figure 3: AP Film after a Latarjet repair Figure 4: Axillary film after a Latarjet repair case series of 2,000 patients undergoing Latarjet procedures and noted a failure rate of 1%, with 83% of patients returning to their preinjury sports 10. The Latarjet procedure can also be undertaken arthroscopically. A meta-analysis comparing open and arthroscopic Latarjet procedure found that although they both provided a comparable clinical outcome with a less than 3.5% recurrence rate, the arthroscopic procedure was significantly more expensive as a result of the longer operation time and the use of additional equipment 11. Although infrequent, glenoid bone loss can occur posteriorly. There are varied results in the literature. Barbier et al. published a case series of eight patients who underwent tricortical bone grafting for posterior glenoid bone loss. At three year follow up 80% of patients reported a satisfactory outcome, although none had resumed their normal sporting activities at the preinjury level 12. In a different series of fifteen patients, Struck et al. had satisfactory results and 67% had resumed sport at the preinjury level 13. Humeral Bone Loss Posterior humeral defects are reconstructed according to their size and depth. Hill-Sachs lesions under 20% are treated conservatively 14. Lesions of more than 20% can be managed either by filling the defect or resurfacing the humeral head. Hill-Sachs lesions between 20% and 30% are more likely to involve the articulation, thus they would benefit from remplissage. Remplissage involves the tenodesis of the infraspinatus tendon into the defect. Buza et al. published a systematic review of six studies on the use of arthroscopic remplissage and found an overall 5.4% recurrence rate in 167 patients 15. The management of Hill-Sachs lesions between 30% and 40% is controversial. Patients with defects of this size can be potentially managed with remplissage, an osteochondral allograft transplantation (OAT) procedure or a partial resurfacing prosthesis such as HemiCap 14. Garcia et al. published a case series comparing 19 patients who underwent OAT procedures and 20 who underwent remplissage. They reported a 50% decrease in the recurrence rate with the remplissage technique 16. Miniaci reported a case series of 18 patients who underwent OAT procedure and reported no recurrences 17. Although, a systematic review of 12 studies including 35 patients reported that though there was a significant improvement in their shoulder motion and only 3% of patients suffered from recurrent instability, there was a 32% incidence of residual pain and a complication rate of 22% 18. In lesions involving greater than 40% of the joint surface, patients require either partial resurfacing or a shoulder arthroplasty. Sweet et al. published a retrospective case series of nineteen patients treated with a HemiCAP and reported no major complications 19. Bipolar Defects Bone loss on both the glenoid and the humeral head (bipolar defects) following dislocation has a prevalence rate of 33% in primary instability and 62% in recurrent instability 20. A CT study of 100 patients reported an even higher incidence of bone loss with Hills-Sachs lesions in 94% and glenoid bone loss in 86% of patients 21. Burkhart et al. identified that if a Hill-Sachs lesion engaged with the glenoid at 90 o of external rotation and abduction, the shoulder was at high risk of recurrence dislocation despite a Bankart repair 1. Yamamoto et al. further identified an area they defined as the glenoid track 5. This is a band of the articular surface on the postero-superior humeral head. Bone loss outside this area is associated with a loss of stability 5,22. If there is glenoid bone loss, then the glenoid track reduces in width. A Hill-Sachs lesion that lies within the area of the glenoid track is said to be on-track, whereas one that lies outside is off-track 23. An off-track lesion is associated with an increased
Volume 05 / Issue 01 / March 2017 Page 53 boa.ac.uk risk of failure following soft tissue Bankart repair alone 1. Tracking has redefined the management of bipolar bony defects. Shaha et al. published a case series, which confirmed that the glenoid track concept was a better predictor of the failure of arthroscopic stabilisation than the measurement of glenoid bone loss 24. It therefore follows that on-track lesions can be successfully treated with arthroscopic stabilisation alone. The aim of treating off-track lesions is to turn them into ontrack lesions. This can be done by treating the humeral bone loss or increasing the glenoid track. The use of the Latarjet procedure to enlarge the glenoid track and converting an off-track Hill-Sachs lesion to an on-track has been reported, but no longterm follow up results have been * published 21,25. Using tracking we believe that an algorithm can be used for managing these patients (Figure 5). Conclusion Bone loss post GHJ dislocation is a challenging problem. Pre-operative and intra-operative planning is of paramount importance to avoid high recurrent dislocation rates. The concept of the glenoid track and on/off-track lesions is redefining the management of bipolar bone loss. The literature is limited to level 4 and 5 evidence and better studies are required to definitively evaluate the different modalities of treatment for bone loss in shoulder instability. Originally from New York, Dr Chiang obtained his MSc in Human Anatomy from the University of Edinburgh after his medical training. He completed his Foundation Training in the Severn Deanery and is currently a Senior House Officer in Trauma and Orthopaedics at Epsom and St Heliers NHS Hospitals and is pursuing a career in Trauma and Orthopaedics. Correspondence Email: Cchiang@doctors.org.uk References References can be found online at www.boa.ac.uk/publications/jto or by scanning the QR Code. Figure 5: Bipolar Bone Loss Management Algorithm *Young patients with high demand (High ISIS score), may require fixation with glenoid bone loss of 15%.
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