BMJ  2005;330:197 (22 January), doi:10.1136/bmj.330.7484.197-b

Letter

Computer assisted knee arthroplasty is here today

EDITOR—Gidwani et al summarise the orthopaedic options for painful arthritis of the knee.¹ As they say, computer assisted surgery is not standard practice for most orthopaedic surgeons in the United Kingdom. Many cite a lack of long term follow up data for this technique to justify their reluctance to embrace this technology.

However, navigated arthroplasty surgery has been widely validated in the orthopaedic literature.^{2 3} Lower limb mechanical alignment is one of the principal factors determining the survival of a total knee arthroplasty. As many as 10-15% of all knee prostheses ultimately require revision, many because of poor quality placement of the prosthetic components.⁴ The failure rate of poorly aligned implants is more than twice that of well aligned implants.⁵

The main reason for poor alignment arises from the difficulty of using anatomical reference points, and human judgment alone cannot ensure reproducible alignment. Mechanical alignment outcomes obtained using computer assisted surgery have consistently been superior to those obtained using traditional alignment methods.^{2 3} Most data on survival of total knee arthroplasties originate from centres specialising in such surgery and therefore do not reflect the normal Gaussian spread of outcome obtained throughout the country.

Computer assisted arthroplasty narrows the spread of alignment and so improves the long term outcome of such surgery. Interestingly, few orthopaedic surgeons formally assess postoperative mechanical alignment by lower limb alignment films or computer tomography. Despite their inability to assess their outcomes, many would state that their technique does not require modification. We think this shows a lack of insight which must be addressed to maximise the survival of arthroplasties.

graemeholt{at}btinternet.com, Hairmyres Hospital, East Kilbride, Glasgow G75 8RG

Hairmyres Hospital, East Kilbride, Glasgow G75 8RG

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Competing interests: None declared.

References

1. Gidwani S, Fairbank A. The orthopaedic approach to managing osteoarthritis of the knee. BMJ 2004;329: 1220-4. (20 November.)[Free Full Text]
2. Oberst M, Bersch C, Wurstlin S, Holz U. CT analysis of leg alignment after conventional vs. navigated knee prosthesis implantation. Initial results of a controlled, prospective and randomised study. Unfallchirurg 2003;106: 941-8.[Medline]
3. Saragaglia D, Picard F, Chaussard C, Montbarbon E, Leitner F, Cinquin P. Computer assisted knee arthroplasty: comparison with a conventional procedure. Rev Chir Orthop Reparatrice Appar Mot 2001;87: 18-28.[Medline]
4. Coyte PC, Hawker G, Croxford R, Wright JG. Revision knee replacement in Ontario, Canada. J Bone Joint Surg Am 1999;81: 773-82.[Abstract/Free Full Text]
5. Ritter MA, Faris PM, Keating EM, Meding JB. Post-operative alignment of total knee replacement. Its effect on survival. Clin Orthop 1994;299: 153-6.

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Relevant Article

The orthopaedic approach to managing osteoarthritis of the knee

Sam Gidwani and Adrian Fairbank
BMJ 2004 329: 1220-1224. [Extract] [Full Text] [PDF]