Radiostereographic analysis of a shoulder surface replacement: does hydroxyapatite have a place?

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Radiology

Background:

• Humeral head resurfacing is a common UK treatment for shoulder osteoarthritis (OA).
• The Global CAP prosthesis is used, with variations in surface coatings.
• Assessing prosthesis fixation and patient outcomes is crucial for treatment efficacy.

Purpose of the Study:

• To compare the efficacy of two prosthesis coatings (Porocoat and DuoFix hydroxyapatite [HA]) in shoulder OA treatment.
• To evaluate prosthesis migration, pain reduction, and functional outcomes over two years.
• To determine if HA coating improves prosthesis fixation compared to Porocoat.

Main Methods:

• A prospective randomized study of 20 patients with shoulder OA.
• Two groups received Global CAP prostheses with Porocoat or DuoFix HA coatings.
• Patients were followed for two years, assessing pain, Constant-Murley, ASES scores, and prosthesis migration via radiostereometric analysis.

Main Results:

• Significant reductions in pain (p = 0.003) and improvements in Constant (p = 0.001) and ASES (p = 0.006) scores were observed.
• Mean prosthesis migration at three months was similar for both groups (Porocoat: 0.78 mm, DuoFix HA: 0.72 mm).
• Migration rates plateaued by three months post-operatively; HA coating did not significantly improve fixation.

Conclusions:

• The addition of HA coating to the sintered surface does not enhance the fixation of the Global CAP prosthesis.
• Both Porocoat and DuoFix HA coatings provide similar clinical outcomes and migration patterns.
• Further investigation may be needed for cases involving bone grafting, as one such case required revision.