Before embarking on a surgical revision of a shoulder arthroplasty, it is important to determine the nature of the patient’s problems. The following is a list of the common causes of shoulder arthroplasty failure:
(1) Infection
(2) Reaction to polyethylene or polymethylmethacrylate
(3) Fracture
(4) Stiffness
(a) Poor rehabilitation
(b) Unwanted bone
(c) Tuberosity malunion
(d) Overstuffing of the joint
(5) Instability
(a) Anterior
(i) Subscapularis deficiency
(ii) Glenoid component anteversion
(iii) Tuberosity nonunion
(iv) Supraspinatus/infraspinatus defect
(v) Humeral component anteversion or anterior head offset
(vi) Insufficient anterior glenoid bone
(b) Posterior
(i) Glenoid component retroversion
(ii) Posterior cuff defect
(iii) Excessive humeral component retroversion or posterior head offset
(iv) Insufficient posterior glenoid bone
(c) Superior
(i) Loss of rotator cuff
(ii) Loss of coracoacromial arch
(6) Weakness
(a) Reduced muscle strength
(b) Subscapularis deficiency
(c) Supraspinatus/infraspinatus deficiency
(d) Tuberosity nonunion or malunion
(e) Deltoid detachment
(f) Nerve injury
(7) Humeral component
(a) Malpositioned
(b) Loose
(8) Glenoid
(a) Bone eroded (hemiarthroplasty)
(b) Component malpositioned
(c) Component loose
The history and previous records are reviewed to learn the status of the patient and shoulder prior to the index arthroplasty. What were the details of the reconstruction including the manufacturer, model and size of the prostheses? How was the rehabilitation conducted? Is there evidence of infection or allergic reaction? Has there been an intercurrent injury? What is the patient’s status with respect to nutrition, pain medications, smoking, alcohol, and other concurrent health conditions?
The workup includes a detailed examination of the motion, stability, strength and smoothness of the shoulder.
EMG’s and nerve conduction studies, CT scans, and expert sonography may be useful in evaluating the nerve function, bone, and rotator cuff, respectively.
Laboratory studies include a CBC, sedimentation rate, and serum albumin.
Radiographs include an anteroposterior view in the plane of the scapula, an axillary view, and a full humeral view, all of high quality. Here is an AP view and an axillary view showing a glenoid component that has completely loosened from the bone and is floating free within the joint (two white dots near the letter "G").
In cases of instability, examination under fluoroscopy may be useful. The radiographic evaluation must confirm the type and size of components, their position, and the nature of their fixation to bone. The preoperative plan must include a definitive plan for removal of the glenoid and humeral components should this prove necessary, as well as a plan for reconstruction of the humerus and the glenoid after prosthesis removal. If removal of a cemented humeral component may be necessary, it is essential to have a full set of cement removal tools, a high speed saw capable of cutting a prosthetic stem, fluoroscopy, and long stem prostheses of all possible sizes. The possible need for bone and tendon graft is also anticipated.
In cases of instability, examination under fluoroscopy may be useful. The radiographic evaluation must confirm the type and size of components, their position, and the nature of their fixation to bone. The preoperative plan must include a definitive plan for removal of the glenoid and humeral components should this prove necessary, as well as a plan for reconstruction of the humerus and the glenoid after prosthesis removal. If removal of a cemented humeral component may be necessary, it is essential to have a full set of cement removal tools, a high speed saw capable of cutting a prosthetic stem, fluoroscopy, and long stem prostheses of all possible sizes. The possible need for bone and tendon graft is also anticipated.
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