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The Bone & Joint Journal
Vol. 99-B, Issue 8 | Pages 1047 - 1052
1 Aug 2017
Ikawa T Takemura S Kim M Takaoka K Minoda Y Kadoya Y

Aims

The aim of this study was to evaluate the effects of using a portable, accelerometer-based surgical navigation system (KneeAlign2) in total knee arthroplasty (TKA) on the alignment of the femoral component, and blood loss.

Patients and Methods

A total of 241 consecutive patients with primary osteoarthritis of the knee were enrolled in this prospective, randomised controlled study. There were 207 women and 34 men. The mean age of the patients was 74.0 years (57 to 89). The KneeAlign2 system was used for distal femoral resection in 121 patients (KA2 group) and a conventional intramedullary femoral guide was used in 120 patients (IM group).


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 10 | Pages 1327 - 1330
1 Oct 2006
Tokuhara Y Kadoya Y Kanekasu K Kondo M Kobayashi A Takaoka K

The shape of the flexion gap in 20 normal knees was evaluated by axial radiography of the distal femur, and the results compared with those obtained in a previous study by MRI. The observed asymmetry was reduced by 29% using radiography, with a mean value of 3.6° (1.5° to 6.3°) compared with that obtained by MRI of 5.1° (2.6° to 9.5°), a mean discrepancy of 1.49°. The results obtained by radiography and MRI showed a strong correlation (r = 0.78).

Axial radiography is acceptable for the evaluation of the flexion gap and is less expensive and more comfortable to perform than MRI. Additionally, no metallic artefact occurs when the radiological method is used for assessment after arthroplasty.


The Journal of Bone & Joint Surgery British Volume
Vol. 86-B, Issue 8 | Pages 1133 - 1136
1 Nov 2004
Tokuhara Y Kadoya Y Nakagawa S Kobayashi A Takaoka K

Varus and valgus joint laxity of the normal living knee in flexion was assessed using MRI. Twenty knees were flexed to 90° and were imaged in neutral and under a varus-valgus stress in an open MRI system. The configuration of the tibiofemoral joint gap was studied in slices which crossed the epicondyles of the femur.

When a varus stress was applied, the lateral joint gap opened by 6.7 ± 1.9 mm (mean ± sd; 2.1 to 9.2) whereas the medial joint gap opened by only by a mean of 2.1 ± 1.1 mm (0.2 to 4.2). These discrepancies indicate that the tibiofemoral flexion gap in the normal knee is not rectangular and that the lateral joint gap is significantly lax. These results may be useful for adequate soft-tissue balancing and bone resection in total knee arthroplasty and reconstruction surgery on ligaments.


The Journal of Bone & Joint Surgery British Volume
Vol. 82-B, Issue 8 | Pages 1199 - 1200
1 Nov 2000
Nakagawa S Kadoya Y Todo S Kobayashi A Sakamoto H Freeman MAR Yamano Y

We studied active flexion from 90° to 133° and passive flexion to 162° using MRI in 20 unloaded knees in Japanese subjects. Flexion over this arc is accompanied by backward movement of the medial femoral condyle of 4.0 mm and by backward movement laterally of 15 mm, i.e., by internal rotation of the tibia. At 162° the lateral femoral condyle lies posterior to the tibia.


The Journal of Bone & Joint Surgery British Volume
Vol. 79-B, Issue 5 | Pages 844 - 848
1 Sep 1997
Kobayashi A Freeman MAR Bonfield W Kadoya Y Yamac T Al-Saffar N Scott G Revell PA

Our aim was to analyse the influence of the size, shape and number of particles on the pathogenesis of osteolysis. We obtained peri-implant tissues from 18 patients having revision surgery for aseptically loosened Freeman total knee replacements (10), Charnley total hip replacements (3) and Imperial College/London Hospital double-cup surface hip replacements (5). The size and shape of the polyethylene particles were characterised using SEM and their concentration was calculated. The results were analysed with reference to the presence of radiological osteolysis.

The concentration of polyethylene particles in 6 areas with osteolysis was significantly higher than that in 12 areas without osteolysis. There were no significant differences between the size and shape of the particles in these two groups.

We conclude that the most critical factor in the pathogenesis of osteolysis is the concentration of polyethylene particles accumulated in the tissue.