Summary

Proximal Femoral malrotation correction frequently successfully resolves hip impingement even in the presence of intra-articular CAM/pincer pathomorphology.

Abstract

Introduction.
It is recognised that hip impingement can be caused by intra-articular pathology (CAM/pincer) and/or a combined femoral/acetabular version abnormality. The latter is treated based on the severity of predominant component. Proximal Femoral (PF) malrotation treatment includes Proximal Femoral Derotation Osteotomy (PFDO). We aimed to determine PFDO clinical effectiveness in patients with hip symptoms.

Materials.
A review of patients undergoing PFDO between 2018-2020. Sub-trochanteric PFDO was routinely stabilised with IM nail (Metatan,S&N). We reviewed our management of femoral torsion and associated MRI-defined intra-articular pathomorphology: CAM/pincer ? labral tear and non-CAM/pincer-related labral tears. Combined femoral/acetabular version was assessed using McKibbin Index (MI) (normal ranges: MI–20-50o, acetabular version–10-25o, PF–10-25o). If presenting symptoms resolved, patients were discharged at 18months.

Results.
22 patients underwent PFDO for hip pain. Average age–24years (17-38), average follow-up–20months (3-36).

Observed prevalence of version abnormalities in our cohort were:
• MI
o 8–Excessive retroversion (range -5–5o,median–3o),
o 14–Excessive anteversion (51–67o,median–55o);
• Acetabulum
o 11–Relative retroversion (-2–9o,median–4o),
o 11–Normal (11–23o,median–19o);
• PF
o 8–Relative retroversion (-8–5o,median–0o),
o 14–Excessive anteversion (26–54o,median–34o).

Overall, 12 patients settled post-PFDO and were discharged at 18months follow-up.

Of 10 patients with associated MRI-defined CAM/pincer pathomorphology
• 4 had hip arthroscopy prior to PFDO (discharged)
• 1 required hip arthroscopy post-PFDO
• 5 – no hip arthroscopy required (2–discharged, 3– <18months follow-up).

Conclusion.
Patients with hip impingement present with high prevalence of rotational malalignment. Hip arthroscopy for intra-articular pathology prior to malrotation correction is likely to fail. Primary correction of malrotation is crucial and leads to symptom resolution in significant proportion of patients.