This 1999 current concepts review by Tönnis and Heinecke examined 356 hips in 181 patients using CT and plain radiographs. It asked whether abnormal femoral and acetabular anteversion — quantified together as the McKibbin instability index — predicts hip pain, rotational deficits, and osteoarthritis. The study also evaluated outcomes of rotational osteotomy to restore normal anteversion in hips with dysplasia-related osteoarthritis.
When a young adult presents with hip pain, limited internal rotation, and a toeing-out gait, the default diagnosis of 'idiopathic' hip pain misses a correctable geometric cause. This paper established that combined femoral and acetabular anteversion below 20° (McKibbin index <20) is a distinct mechanical entity with a 73% pain prevalence and elevated OA risk — not a normal variant.
In practice: any hip with internal rotation under 20° and external rotation over 40° should be evaluated with CT for torsional deformity. If McKibbin index is <20, rotational osteotomy targeting 15–20° of anteversion should be considered before arthritis becomes irreversible. Rotational correction alone achieves marked pain relief in 90% of cases, far exceeding varus osteotomy alone.
Tönnis's description of anterior labral tears and anterior cartilage wear in hips with absent femoral anteversion. Cited from Ganz's personal communication. Directly preceded Ganz's 2003 landmark paper formally defining femoroacetabular impingement. This paper is where the mechanistic framework for FAI was first articulated in print.
This 1999 current concepts review by Tönnis and Heinecke examined 356 hips in 181 patients using CT and plain radiographs. It asked whether abnormal femoral and acetabular anteversion — quantified together as the McKibbin instability index — predicts hip pain, rotational deficits, and osteoarthritis. The study also evaluated outcomes of rotational osteotomy to restore normal anteversion in hips with dysplasia-related osteoarthritis.
When a young adult presents with hip pain, limited internal rotation, and a toeing-out gait, the default diagnosis of 'idiopathic' hip pain misses a correctable geometric cause. This paper established that combined femoral and acetabular anteversion below 20° (McKibbin index <20) is a distinct mechanical entity with a 73% pain prevalence and elevated OA risk — not a normal variant.
In practice: any hip with internal rotation under 20° and external rotation over 40° should be evaluated with CT for torsional deformity. If McKibbin index is <20, rotational osteotomy targeting 15–20° of anteversion should be considered before arthritis becomes irreversible. Rotational correction alone achieves marked pain relief in 90% of cases, far exceeding varus osteotomy alone.
Tönnis's description of anterior labral tears and anterior cartilage wear in hips with absent femoral anteversion. Cited from Ganz's personal communication. Directly preceded Ganz's 2003 landmark paper formally defining femoroacetabular impingement. This paper is where the mechanistic framework for FAI was first articulated in print.