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Knee: Y. Yamada, Y. Toritsuka, H. Yoshikawa, K. Sugamoto, S. Horibe, and K. Shino Morphological analysis of the femoral trochlea in patients with recurrent dislocation of the patella using three-dimensional computer models J Bone Joint Surg Br 2007; 89-B: 746-751 [Abstract] [Full text] [PDF]

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Yukiyoshi Toritsuka, Amagasaki, Hyogo, Japan   (31 August 2007)

Morphological analysis of the femoral trochlea in patients with recurrent dislocation of the patella

Caroline B Hing   (2 August 2007)

Authors' reply 31 August 2007
Yukiyoshi Toritsuka, Orthopaedic surgeon Othopaedic Sports Medicine, Kansai Rosai Hospital, Amagasaki, Hyogo, Japan Send letter to journal: Re: Authors' reply toritsuka{at}kanrou.net Yukiyoshi Toritsuka, et al.	Sir, We thank Dr Hing for her comments and observations pointing out the importance of the trochlear groove position based on their study using computed tomography. We intended to express the characteristics of the femoral trochlea in patients with patellar dislocation and precisely evaluated the extent of articular cartilage and the shape of the trochlea using MR images, however, we did not notice a difference in the position of the trochlear groove. After reading their letter we reviewed the 3-D models with articular cartilage focused on the trochlear position. It is very difficult to identify the position of the groove because of its convexity. Cartilage-bone mismatch might be the cause of the discrepancy. Therefore, we can not comment on the importance of the groove position on the operative planning for patellar dislocation. However, we will try to evaluate whether it is possible or not in our system. We deeply appreciate Dr Hing and her co-authors for their thoughtful insights. Y. Toritsuka, MD, PhD, Department of Orthopaedic Sports Medicine, Kansai Rosai Hospital, Amagasaki, Hyogo, Japan.
Morphological analysis of the femoral trochlea in patients with recurrent dislocation of the patella 2 August 2007
Caroline B Hing, Locum Consultant Orthopaedic Surgeon Guy's & St Thomas' Hospitals Send letter to journal: Re: Morphological analysis of the femoral trochlea in patients with recurrent dislocation of the patella CaroH2712{at}aol.com Caroline B Hing	Sir, I read this paper with interest. The authors used three-dimensional computer models acquired from magnetic resonance imaging (MRI) scans of 12 knees (12 patients) with patellofemoral instability (PFI) and compared them with ten control knees (ten subjects). They concluded that the cartilaginous trochlear groove was wider and more convex in patients with PFI. We compared computed tomography (CT) scans of 108 knees from 54 patients with PFI with 197 knees from 102 subjects with normal knees.1 We used a modified Procrustes analysis, basic cubic splines and a principal components analysis to compare shape and position of the trochlear groove between patients with PFI and normal controls. We found the trochlear groove shape differed (p<0.001) between patients who had a patellar dislocation and those who did not. The osseous trochlear groove was shallow and shifted medially in the PFI group. Conversely, in the normal group the medial condyle was more prominent and the trochlear groove deeper and it shifted laterally. We also found that a laterally-based trochlear groove relative to the femur was more important in preventing patellar dislocation than a deeper groove. Whilst we agree that there is a cartilage-bone mismatch in the trochlear groove,2 we found that position of the trochlear groove was more important than shape for preventing patellar dislocation. We consider that the authors should have reported on the relative importance of trochlear groove position compared with shape with resultant consequences for operative planning. C.B. HING FRCS(Tr&Orth), BSc, MSc, MD, Locum Consultant Orthopaedic Surgeon, Guy’s & St Thomas’ Hospitals, London, UK. 1. Hing CB, Shepstone L, Marshall T, Donell ST. A laterally positioned concave trochlear groove prevents patellar dislocation. Clin Orthop Relat Res 2006;447:187-94. 2. Staubli HU, Bosshard C, Porcellini P, Rauschning W. Magnetic resonance imaging for articular cartilage: cartilage-bone mismatch. Clin Sports Med 2000;21:417-33.