5-Years Outcomes of Total Hip Arthroplasty Using a Femoral Neck Preserving Short Stem

Introduction: This prospective multicenter study aimed to determine clinical outcomes after THA using a primary cementless and collarless femoral neck preserving short stem (Collo-MIS, Lima Corporate).

Methods 270 consecutive patients (273 hips) underwent THA; 140 (52%) were women, 130 men (48%). Mean age and BMI of 62±11 (26-90) years and 28±5 (18-47) kg/m². 91% of the patients had primary coxarthrosis. Clinical evaluation, using Harris-Hip-Score (HHS) and ROM, as well as a radiographic analysis by an independent radiologist were carried out preoperatively and postoperatively at 1, 6, 12, 24 and 60 months. As of June 2016, 197 patients (200 hips), 105 women and 92 men were evaluated for their 60 month follow-up.

Results: The cohort’s mean pre-operative HHS significantly increased from 49± 12 (15-91) to 94± 7 (64-100) after 6 months and to 95± 8 (45-100) after 5 years post surgery. 99% of patients showed ‘good’ or ‘excellent’ HHS results with 97% recorded significant pain relief (‘no or slight pain’). Hip ROM improved significantly after 6 month/and after 5 years (flexion: 94° to 103°/109°; external rotation 17° to 26°/30°; abduction 22° to 32°/37°; adduction 14° to 21°/22°). X-rays indicated solid osseointegration in all cases, stability and optimal positioning without stress shielding. No diaphyseal hypertrophy was described. Sclerosis and asymptomatic non-progressive radiolucent lines were reported in 1% and 27% of cases, whereas no case of thigh pain was recorded. 4 revision surgeries were performed due to subsidence of an undersized stem causing impingement. One short stem was replaced, in 3 other cases a larger head size was implanted. No loosening, mechanical failures or dislocations were reported.

Conclusion: Almost all patients showed early functional recovery as well as very good clinical outcomes after 5 years, with overall firm bone in-growth and a 99% survivorship of this short stem prosthesis.