LONG-TERM OUTCOME OF CEMENTLESS HUMERAL STEMS FOR SHOULDER ARTHROPLASTY

Abstract

Purpose of the study: The purpose of this retrospective analysis was to assess long-term clinical and radiological outcome of humeral stems inserted without cement for shoulder arthroplasty.

Material and methods: The series included 37 shoulder arthroplasties (11 simple humerus prostheses and 26 total shoulder arthroplasties) performed between 1985 and 1998. Press-fit humeral stems were used for these patients with primary and posttraumatic shoulder degeneration and osteonecrosis. There were 13 Neer II (3M) prostheses and 24 Modular Shoulder prostheses (3M) which were designed for implantation with cement. Mean follow-up was 9.2 years (range 5.8–13.6 years). This series included 22 women and 15 men, mean age 57.7 years (range 33–82). The Constant score and the Neer classification were noted. Lucent lines, endosoteal erosion, and stem migration or tilt were noted on plain x-rays. A stem was considered ‘at risk’ of loosening in the presence of tilt or migration or lucent lines measuring > 2 mm in > 3 zones.

Results: At last follow-up, the mean non-weighted Constant score was 57/100 (16/95) and according to Neer, outcome was satisfactory in 70%. There was no complication and no revision related to the cementless stem was needed. The radiographic analysis failed to identify any stem migration. Lucent lines were observed for 22 components (59%), endosteal erosion for 12 (32%) and tilt for 5 (14%). Seven stems were considered at risk (19%). The prevalence of at risk stems was not correlated with patient-related or disease-related features, nor to the type of prosthesis, the length of follow-up or clinical outcome in terms of pain, Constant score or Neer classification.

Discussion: Neer initially designed a humeral component to be inserted with cement. This technique provided a humeral fixation which was very reliable, with very few loosenings reported. It was nevertheless very difficult to remove the cemented stem. For this reason, certain surgeons continued to use these stems designed for cemented implantation in a press-fit manner for simple humeral prostheses and for total shoulder arthroplasty.

Conclusion: This study demonstrated the favorable results obtained using these press-fit stems for shoulder arthroplasty. The rate of clinical looseninf was low at long-term follow-up.