Pre-operative templating in THA. Part II: a CT-based strategy to correct architectural hip deformities
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HIP ARTHROPLASTY
Pre‑operative templating in THA. Part II: a CT‑based strategy to correct architectural hip deformities Hideo Kobayashi1 · Alexandre Cech2 · Masanori Kase3 · Geert Pagenstart4,5,6 · Yannick Carrillon2 · Padhraig F. O’Loughlin2,7 · Hugo Bothorel8 · Tarik Aït‑Si‑Selmi2,9 · Michel P. Bonnin2,9 Received: 14 May 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Introduction Pre-operative templating for total hip arthroplasty (THA) remains inaccurate due to improper magnification and alignment. We aimed to describe an improved templating strategy using computed tomography (CT) to predict component sizes and offsets with greater accuracy. Materials and methods We analysed 184 CT images acquired for pre-operative templating of primary THA. We aimed to restore native (pre-arthritic) femoral offset and limb length, by raising the head center to the level of the templated cup center cranio-caudally, but maintaining the pathologic (pre-operative) head center medio-laterally (except in medialized hips). Acetabular offset (AO) and femoral offset (FO) were measured on pre-operative CT scans, during acetate templating, and on post-operative true antero-posterior radiographs. Results The post-operative offsets were within ± 5 mm from templated estimates in 174 hips (91%) for AO, in 116 hips (61%) for FO, in 111 hips (58%) for GO, and in 134 hips (70%) for neck cut level. The post-operative hip architecture reproduced the templated hip architecture within ±5 mm in 77 hips (40%). The agreement between planned and post-operative parameters was moderate for stem size (0.57), cup size (0.62), AO (0.50), but fair for FO (0.45). The AO decreased in most arthritic types, notably in lateralized hips (6.6 mm), but remained unchanged in medialized hips. The FO increased in most arthritic types (1.8–3.1 mm) but remained unchanged in medialized and lateralized hips. Conclusions We described a strategy for pre-operative templating in THA. Despite the accuracy of CT, the authors found significant variations between planned and post-operative reconstructions, which suggest that pre-operative templating should only be used as an approximate guide. Keywords Arthritis · Arthroplasty · Hip · Hip architecture · Pelvis and acetabulum · Pre-operative planning · Templating
Introduction Pre-operative templating is an integral part of total hip arthroplasty (THA), as it helps optimize implant sizing and positioning to correct architectural hip deformities. It * Hugo Bothorel [email protected] 1
Department of Orthopaedic Surgery, Juntendo University, Bunkyo‑ku, Tokyo, Japan
2
Ramsay Santé, Hôpital Privé Jean Mermoz, Centre Orthopédique Santy, Lyon, France
3
Department of Orthopaedic Surgery, Nissan Tamagawa Hospital, Setagayaku, Tokyo, Japan
4
facilitates restoration of native (pre-arthritic) hip architecture, including limb length, femoral offset and hip center of rotation [1–5], and hence optimizes functional outcomes, whilst minimizing dislocation, limb length inequality, periprosthetic
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