Shoulder resurfacing arthroplasty

Shoulder resurfacing arthroplasty is a form of partial shoulder joint replacement for the management of pathologies concerning the humeral head.

History and etymology

The first shoulder arthroplasty was performed by Péan in 1893. The current 3^rd generation arthroplasties were introduced by Neer from the 1950s to 1970s ¹.

Indications

Indications of shoulder resurfacing arthroplasty comprises disease processes affecting the humeral side of the joint and include ¹:

• avascular necrosis (osteonecrosis) of the humeral head
• large Hill-Sachs lesionsdefects
• large focal osteochondral injuries
• fracture malunion
• congenital defects

Additional factors favouring anatomic total shoulder arthroplasty over other forms of shoulder arthroplasty are:

• intact rotator cuff with good tendon and muscle quality
• adequate humeral and glenoid bone stock

Contraindications

Contraindications of shoulder resurfacing arthroplasty are ¹:

• deficient humeral or glenoid bone stock
• complex proximal humeral fractures
• ≥3 fragments displaced >1 cm (>5 mm greater tuberosity) or angulated >45° 
• high grade or full-thickness rotator cuff tears
• extensive mucoid degeneration of the rotator cuff

Prosthesis design

The component for shoulder resurfacing arthroplasty consists of a metal alloy cap with a peg.

Procedure

The surgical technique includes the following steps:

• reaming
• fitting of a metal alloy cap

Complications

Complications of anatomic total shoulder arthroplasty include the following:

• humeral head prosthetic component loosening
• glenoid osteoarthritis

Radiographic features

Plain radiograph

Anteroposterior and lateral views are the initial tests for procedural planning and mainstay in postoperative control and follow-up examinations.

Preprocedural radiographs can aid in the diagnosis and the assessment of the bone stock. Furthermore, radiographs acquired in the erect position can be evaluated for the following features indicating rotator cuff disease ¹:

• static proximal humeral head migration (acromiohumeral distance <7 mm in erect position)
• anterior humeral head subluxation

Post-operative radiographs should show the resurfacing cap flush-mounted to the humeral head and should not show any lucency around the peg. On the lateral view, it should be centred to the glenoid.

Follow-up radiographs should be evaluated for signs of glenoid osteoarthritis including the following:

• joint space narrowing
• subchondral cyst formation
• posterior glenoid wear

US

Ultrasound can be used in the evaluation of the rotator cuff.

CT

CT is used for preoperative planning, in particular, the characterization of glenoid morphology and glenoid version measurements.

MRI

Like ultrasound can be used in the evaluation of the rotator cuff morphology and to exclude rotator cuff tears.

Radiological report

The radiological report should include a description of the following features:

Surgical planning:

• glenoid morphology
• glenoid version
• quality and integrity of the rotator cuff

Postoperative control and follow up:

• implant malposition
• implant loosening
• glenoid erosion
• hardware failure
• signs of infection

Outcomes

Resurfacing shoulder arthroplasty is the most minimalistic type of arthroplasty offering maximal preservation of the original bony anatomy including head-shaft angle humeral head version and posterior head translation.

Advantages

The main advantages of resurfacing shoulder arthroplasty include the following ^1,4:

• preservation of bone stock in young and active patients
• diminished procedural time
• lower incidence of humeral periprosthetic fractures
• easy revision to convention total shoulder replacement if necessary
• fewer metal artefacts on postoperative imaging

Disadvantages

The disadvantages of resurfacing shoulder arthroplasty are the risk of developing glenoid osteoarthritis requiring conversion to total shoulder arthroplasty ¹.

See also

• shoulder arthroplasty (overview)