Open bony augmentation of glenoid bone loss—iliac crest and allograft—surgical technique

CHAPTER 19 Open bony augmentation of glenoid bone loss—iliac crest and allograft—surgical technique



Jon JP. Warner, MD, Anup A. Shah, MD



Key points



image Restoration of glenoid depth and width is paramount for shoulder stability.

image Suspect significant glenoid bone loss in patients with recurrent anterior instability and especially when the force causing dislocation is less than the original injury.

image Perform a detailed physical examination with particular attention to subscapularis function and differentiate unilateral from multidirectional instability.

image Iliac crest and allograft bony augmentation can avoid potential complications encountered with coracoid process transfers.

image Meticulous harvesting and preparing of graft and the proper placement of the graft are essential for successful anatomic reconstruction.


Introduction


The consequence of anterior glenoid bone loss in shoulder instability is well known. Some degree of bone loss exists in most recurrent anterior shoulder instability; however, it has been reported to exist in up to 22% of patients after an initial dislocation.1–3 Burkhart and DeBeer4 found that significant anterior glenoid bone loss results in failure of arthroscopic stabilization procedures, and they advocate open reconstruction of the defect using a coracoid process bone graft. Several authors have described methods to quantify bone loss3,5; however, the technique presented by Gerber and Nyffeler6 is our preference for deciding whether or not to augment the glenoid during preoperative planning. These authors determined that 70% less force was required to dislocate the humeral head from the glenoid when the length of the glenoid bony defect was more than the maximum radius of the glenoid (Fig. 19-1).


image

FIGURE 19-1 Relationship between size of bony defect and dislocation resistance of humeral head. If the glenoid rim length measures more than the maximal glenoid radius, the dislocation resistance decreases to no more than 70% of the value of the intact joint.


(Redrawn from Gerber C et al: Classification of glenohumeral joint instability. Clin Orthop Relat Res 400:65–76, 2002.)


Options for the treatment of shoulder instability with significant glenoid bone loss include the Bristow, Latarjet, and various bone block procedures. Potential complications of the Bristow and Latarjet procedures include loss of motion, development of arthritis, screw loosening and breakage, musculocutaneous and axillary nerve palsy, subscapularis dysfunction, and resorption or nonunion of the coracoid process. Although the risk of these complications can be minimized with excellent surgical technique, the use of iliac crest autograft or allograft can be a good alternative with less risk. The authors prefer to use iliac crest autograft in patients with extensive glenoid bone loss (>40%) and the Latarjet procedure when smaller defects are identified. When >40% of the glenoid is involved, we believe congruency becomes an issue with Latarjet reconstruction.


Although the long-term effects of these alternatives have yet to be determined, Warner et al demonstrated that placing the autogenous tricortical iliac crest bone graft intra-articularly appears to have a high rate of union and stability.7 In addition, the study revealed satisfactory subjective outcomes, and all patients returned to sports participation. Recently, Provencher8 described another technique of reconstructing the anterior glenoid deficiency with the use of distal tibia allograft bone. The authors reported excellent outcomes in all three patients treated with the method and described this operation as not only avoiding the potential complications of coracoid transfer but also claiming it to anatomically restore the articular surface of the glenoid.



Indications/contraindications for iliac crest autograft



• Indications
• Significant anterior glenoid bone loss

• Engaging Hill-Sachs lesion

• Revision cases: failed Bankart lesion (bony and soft tissue) and failed Bristow/Latarjet

• Contraindications:
• Glenoid fractures involving more than one-third of the articular surface—fracture should be fixed

• Severe arthritis

• Relative contraindications (should be repaired/reconstructed in staged or at same setting):
• Shoulder instability resulting from subscapularis tear

• Subscapularis insufficiency

• Seizures

• Moderate arthritis


Preoperative history, examination, and radiographic findings



Preoperative history


A detailed history is compulsory for patients with recurrent instability. Determining the patient’s preinjury activity level, cause of initial dislocation, arm position at the time of dislocation, the frequency of subsequent dislocations, and the force necessary for recurrence are critical in formulating the best treatment plan. Certain factors in the patient’s history may be suggestive of glenoid bone loss. Often, instability in lower ranges of abduction or with less force is indicative of a bony defect. Additionally, a high-energy mechanism with an axial load applied to the glenohumeral joint should arouse suspicion of bone involvement. Also, the patient should be questioned about mechanical symptoms including catching and locking, which may indicate engaging bony defects or displaced labral tears. The patients’ previous nonsurgical and surgical treatments (including prior imaging, as well as clinical and operative notes) should be reviewed as well.



Examination findings


A careful examination of both shoulders should be performed. Upon inspection, the physician should note prior surgical scars, muscular atrophy, and deformity and evaluate for scapular dyskinesia. Passive and active range of motion must be documented along with rotator cuff strength and positive stress tests. Particular attention to subscapularis function is essential, especially in patients who have undergone prior open surgical procedures. Positive belly-press and/or lift-off tests, pain with passive external rotation and/or even increased passive external rotation compared to the contralateral shoulder is indicative of subscapularis insufficiency. Additionally, a detailed neurologic examination should be performed and documented, specifically noting the function of the axillary and musculocutaneous nerves. The suprascapular nerve also has been associated with instability, and if there is suspicion for injury, electromyogram (EMG) and nerve conduction velocity (NCV) should be performed.


An instability examination should be performed to evaluate the direction and quantify the magnitude of laxity. Differentiating unilateral instability from multidirectional instability can be difficult. It is thought that large sulcus sign with symptoms of instability is indicative of multidirectional instability.



Radiographic findings


Plain radiographs and computer tomography (CT) are the recommended radiographic studies to document the direction of instability and evaluate osseous lesions. Anteroposterior views of the shoulder in internal and external rotation, an axillary lateral view, the Stryker notch view, and the Bernageau view will help diagnose most Hill-Sachs and glenoid fracture lesions. If an osseous lesion is suspected, a CT arthrogram and three-dimensional imaging of the glenoid are helpful in quantifying bone loss (Fig. 19-2). The CT arthrogram better defines the extent of bone loss when compared with an MR arthrogram of the shoulder. The dye in the CT arthrogram will outline the cartilaginous erosion and the three-dimensional reconstruction will allow assessment of bone loss according to Gerber et al.6 When evaluating the CT or MRI, the oblique sagittal reconstruction views provide the images necessary to calculate glenoid bone loss.


image

FIGURE 19-2 A, Three-dimensional CT reconstruction demonstrating significant glenoid bone loss. B, Eroded anterior glenoid lip, deficient anterior glenoid lip. Loss of the glenoid labrum, the anterior glenoid cartilage, and anterior glenoid bone can each contribute to diminished resistance to translation from the centered position. C, Loss of the anterior bony lip. Deficiency of the bony lip of the glenoid compromises the potential for reattaching the residual capsule and labrum at their physiologic length.


(B and C from Matsen FA III et al: Shoulder surgery: principles and procedures, Philadelphia, 2004, WB Saunders, p 153.)



Description of technique for iliac crest autograft



• Surgical anatomy:
• Identify coracoid, acromion, acromioclavicular joint, and clavicle.

• Patient position:
• Place the patient in a beach chair position with the head at about 30 degrees of elevation.

• The shoulder girdle should be kept free to allow complete motion.

• Place bump underneath ipsilateral hip.

• Drape and prep the arm, chest, and anterior iliac crest region.

• Surgical exposure
• Confirm appropriate instruments in room

• Anterior glenoid
• Make an anterior deltopectoral incision with arm in slight abduction and forward flexion to relax deltoid and deep tissues.

• The incision is lateral to the coracoid process and more vertical than an arthroplasty incision.

• Retract the cephalic vein laterally and dissect down to the clavipectoral fascia.

• Identify the interval between the conjoined tendon and the subscapularis and place a narrow retractor beneath the conjoined tendon and a narrow Homan retractor above coracoacromial ligament.

Related posts:

Pathology and findings in patients with multidirectional instability Rehabilitation: return-to-play and in-season guidelines Radiographic studies and findings Open treatment of multidirectional instability—surgical technique Humeral head defects—biomechanics, measurements, and treatments Nonoperative rehabilitation for traumatic and atraumatic glenohumeral instability

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Jan 21, 2017 | Posted by in ORTHOPEDIC | Comments Off on Open bony augmentation of glenoid bone loss—iliac crest and allograft—surgical technique

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