Computer-Assisted femoral head reduction osteotomies: An approach for anatomic reconstruction of severely deformed Legg-Calvé-Perthes hips. A pilot study of six patients

Abstract

Background Legg–Calvé–Perthes (LCP) is a common orthopedic childhood disease that causes a deformity of the femoral head and to an adaptive deformity of the acetabulum. The altered joint biomechanics can result in early joint degeneration that requires total hip arthroplasty. In 2002, Ganz et al. introduced the femoral head reduction osteotomy (FHRO) as a direct joint-preserving treatment. The procedure remains one of the most challenging in hip surgery. Computer-based 3D preoperative planning and patient-specific navigation instruments have been successfully used to reduce technical complexity in other anatomies. The purpose of this study was to report the first results in the treatment of 6 patients to investigate whether our approach is feasible and safe.Methods In this retrospective pilot study, 6 LCP patients were treated with FHRO in multiple centers between May 2017 and June 2019. Based on patient-specific 3D-models of the hips, the surgeries were simulated in a step-wise fashion. Patient-specific instruments tailored for FHRO were designed, 3D-printed and used in the surgeries for navigating the osteotomies. The results were assessed radiographically [diameter index, sphericity index, Stulberg classification, extrusion index, LCE-, Tönnis-, CCD-angle and Shenton line] and the time and costs were recorded. Radiologic values were tested for normal distribution using the Shapiro–Wilk test and for significance using Wilcoxon signed-rank test.Results The sphericity index improved postoperatively by 20% (p = 0.028). The postoperative diameter of the femoral head differed by only 1.8% (p = 0.043) from the contralateral side and Stulberg grading improved from poor coxarthrosis outcome to good outcome (p = 0.026). All patients underwent acetabular reorientation by periacetabular osteotomy. The average time (in minutes) for preliminary analysis, computer simulation and patient-specific instrument design was 63 (±48), 156 (±64) and 105 (±68.5), respectively.Conclusion The clinical feasibility of our approach to FHRO has been demonstrated. The results showed significant improvement compared to the preoperative situation. All operations were performed by experienced surgeons; nevertheless, three complications occurred, showing that FHRO remains one of the most complex hip surgeries even with computer assistance. However, none of the complications were directly related to the simulation or the navigation technique.

Intraarticular hip preservation procedures in healed Perthes disease: a systemic review and meta-analysis

“…To the best of the authors’ knowledge, no comparative studies directly compared the clinical outcomes of RFNL versus FHRO. However, their results were in line with recent reports showing a significant improvement in hip function, ROM, and postoperative pain following RFNL and FHRO 17,27. The authors recommend interpreting those results cautiously because the follow-up duration within the studies was limited.…”

“…However, their results were in line with recent reports showing a significant improvement in hip function, ROM, and postoperative pain following RFNL and FHRO. 17,27 The authors recommend interpreting those results cautiously because the follow-up duration within the studies was limited. A sufficiently long follow-up is crucial to ensure the continuity of the excellent early results and determine whether these procedures will alter the natural history of the disease.…”

A New Approach to Orthopedic Surgery Planning Using Deep Reinforcement Learning and Simulation

“…Computer-assisted 3D surgery planning for FHRO is still in its infancy and thus it consists of an extensive manual surgery planning process performed in collaboration between the surgeons and the technical staff. Currently in our clinics, planning is performed on CT-reconstructed 3D bone models using an in-house planning software [9]. The software allows the user to define 3D planes, which can be placed and moved freely in 3D space to define the osteotomies.…”

“…After simulating the osteotomies, the mobile fragment can be reoriented to its desired position through mouse interaction. During planning, five main clinical criteria are considered [9]. First, the reconstructed femoral head must adhere to a spherical geometry.…”

“…1 C). The creation of a surgery plan is a difficult three-dimensional (3D) geometrical problem, which can take up to several hours per patient [9], since 16 partially interdependent parameters have to be defined to fully describe the location of the two cutting planes and the mobile fragment. This illustrates the necessity of an automatic planning approach that reduces manual workload and treatment costs.…”