Periacetabular metastases: Proposed extension of the Harrington classification

To describe the functional outcomes, complications, and reconstruction types in patients with periacetabular metastases and to propose an extension of the Harrington classification.

Twenty-eight patients (13 males, 15 females) with a mean age of 63.8 ± 15.5 years presented with periacetabular metastases from January 2010 to December 2021. The periacetabular metastases were graded according to Harrington's classification, with four additional categories introduced: A) joint involvement, B) Enneking zone 1 involvement, C) pathological acetabular fracture, and X) none of the above. All patients underwent surgery at a single national referral center.

Based on the Harrington classification, the acetabular destruction results were as follows: Class 1, two cases (7 %); Class 2, eight cases (29 %); Class 3, 17 cases (61 %); and Class 4, one case (3 %). The results for the additional categories were: A, five cases (18 %); B, five cases (18 %); C, seven cases (25 %); and X, 11 cases (39 %). The most frequent type of reconstruction was total hip prosthesis with a reinforcement ring. Four patients (14 %) required reintervention. After a mean follow-up of 43 ± 45 months (range 2-144), seven patients (25 %) could walk unaided, 16 (57 %) required assistance, and five (18 %) could not walk. Three patients (11 %) died before the third postoperative month.

Most patients in this study achieved functional outcomes that allowed ambulation. The type of reconstruction was determined by the classification of the bone defect. We propose extending Harrington's classification to include the four additional categories introduced in this study.