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J Knee Surg 2019; 32(02): 146-152
DOI: 10.1055/s-0038-1636912
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Posterior Condyle Offset and Maximum Knee Flexion Following a Cruciate Retaining Total Knee Arthroplasty

Wei Wang
1   Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
2   Department of Orthopaedic Surgery, Second Hospital of Xi'an Jiao Tong University, Xi'an, China
,
Bin Yue
1   Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
3   Department of Orthopaedic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
,
JianHua Wang
1   Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
4   Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
,
Hany Bedair
1   Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
5   Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
,
Harry Rubash
1   Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
5   Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
,
Guoan Li
1   Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
› Author Affiliations
Further Information

Publication History

22 September 2017

28 January 2018

Publication Date:
07 March 2018 (online)

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Abstract

Inconsistent data has been reported on the effect of the femoral posterior condyle offset (PCO) on the maximal knee flexion after total knee arthroplasty (TKA). This study investigated the relationship between the postoperative changes of the PCO and the changes of maximal knee flexion after a cruciate retaining (CR) TKA. Nine patients with medial osteoarthritis (OA) in one knee were investigated. Before operation, each index knee was magnetic resonance imaging (MRI) scanned for construction of a three-dimensional (3D) knee model. The patient then performed a maximal weight-bearing (WB) flexion and the index knee flexion was measured using a dual fluoroscopy technique. At an average of 8 months after a CR TKA, all patients performed the same WB knee flexion. The postoperative changes of the PCO, the posterior cruciate ligament (PCL) elongation, and the posterior tibial slope (PTS) were determined. The postoperative changes of maximal knee flexion were determined by comparing with the preoperative maximal flexion angles of the knee. The correlations of the postoperative changes of PCO and PTS with the postoperative changes of the maximal flexion angle and PCL elongation of the knee were analyzed. The preoperative PCO (28.5 ± 4.5 mm) was significantly smaller than the postoperative PCO (31.1 ± 5.1 mm) (p < 0.05). The increasing of PCO after surgery is correlated with the decreasing of maximal knee flexion angle (r = 0.74) and the increasing of PCL elongation (r = 0.64) after the TKA. The PTS was not found to change significantly after the TKA and was not significantly correlated to the maximal knee flexion angle and PCL elongation. The postoperative increases of the PCO were shown to cause overstretching of the PCL and poor flexion angle of the knee after the CR TKA. Restoration of PCO could help optimize the maximal flexion of the knee after the TKA with consideration about PCL tension.

Keywords

total knee arthroplasty - total knee replacement - femoral condyle - femoral condyle height - posterior condyle offset - high flexion - posterior tibial slope