Challenges and Long-Term Outcomes of Cementless Total Hip Arthroplasty in Patients Under 30: A 24-Year Follow-Up Study with a Minimum 8-Year Follow-Up, Focused on Developmental Dysplasia of the Hip

Background: Total hip arthroplasty (THA) is a well-established and effective treatment for advanced osteoarthritis (OA) of the hip joint. While commonly performed in older patients, THA is increasingly used in younger individuals, especially in cases of secondary coxarthrosis. Technological advances have led to the development of specialized implants, which allow surgeons to address severe post-inflammatory or dysplastic deformities. Younger patients undergoing THA, often in their 20s or 30s, present higher functional expectations. Despite limited long-term studies, research indicates a higher rate of revision surgeries in this age group compared to older populations, making these procedures a unique challenge. Methods: This retrospective study analyzed 5263 primary total hip arthroplasties (THAs) performed at our center between May 1985 and December 2016. After excluding cemented and hybrid implants, as well as patients lost to follow-up or with other etiologies, 101 uncemented THA procedures in 92 patients aged 30 years or younger were included. The majority (64.4%) were due to dysplastic coxarthrosis (DDH), while avascular necrosis (26.7%) and juvenile rheumatoid arthritis (8.9%) accounted for the rest. The average patient age was 25.6 years, with a mean follow-up period of over 24 years. Surgical technique involved the anterolateral approach, with implants placed in the true acetabular region. Implants included Munich/Plasmacup, Mittelmeier, and P-M designs. Implant survival was estimated using the Kaplan–Meier estimator to determine the probability of implant longevity over the follow-up period. Outcomes were assessed using Merle d’Aubigné and Postel scores, modified by Charnley, alongside radiographic evaluations based on the Crowe, De Lee, and Gruen classifications. Results: Preoperatively radiological assessment of all hips was classified as grade IV according to the Kellgren–Lawrence scale. Over an average follow-up of 24 years, final outcomes using the modified Merle d’Aubigné and Postel (MAP) classification were excellent in 24%, good in 37%, satisfactory in 8%, and poor in 32% of cases. Results compared between DDH group and control group indicate significantly more poor results for the DDH group compared to the control group (p-value < 0.05). All poor outcomes were associated with prosthesis loosening, primarily involving P-M and Mittelmeier acetabular components. Complications included intraoperative fractures in five cases, peripheral nerve dysfunction in six cases, and heterotopic ossification in eight cases. Postoperative pain scores on the VAS scale improved from 6.8 to 1.7. The Kaplan–Meier estimator indicated 10-year survival rates of 85.2% for the entire prosthesis, with 69.8% survival at 15 years and 54.5% at 20 years. For each period the bio-functionality according to Kaplan–Meier estimator was in favor of the control group. Conclusions: Cementless THA in patients aged 30 or younger has demonstrated itself to be an efficacious treatment for hip osteoarthritis, yielding favorable bio-functional outcomes in both short- and long-term follow-up. Nevertheless, THA performed in the context of developmental dysplasia of the hip (DDH) carries a significantly elevated risk of postoperative complications, most notably aseptic loosening, which critically undermines implant survival rates. Given the young demographic and the anticipated prolonged functional lifespan of the prosthesis, there is an increased propensity for loosening over time, necessitating vigilant and sustained postoperative surveillance.