No effect of obesity on limb and component alignment after computer-assisted total knee arthroplasty☆
Introduction
Risk of revision after total knee arthroplasty (TKA) is significantly higher when obesity is combined with malalignment of tibial component or the limb [1]. Reports have suggested that implant survival is significantly lower in obese patients (60–92%) in the long-term when compared to non-obese individuals (89–98.5%) [2], [3], [4], [5], [6] with loosening of tibial components and polyethylene wear being the major causes of revision [4], [5]. Hence it is all the more important to ensure symmetric loading of implant and bone in the obese by accurate implant positioning and restoration of mechanical axis.
Conventional techniques have shown lower consistency in achieving accurate limb and component alignment when compared to navigation techniques during TKA [7], [8], [9], [10], [11], [12], [13], [14]. Furthermore, recent studies have reported greater risk for limb malalignment with conventional TKAs when performed in the obese [15], [16]. Computer navigation using the optical tracking system locates the centre of the femoral head, centre of the knee joint and the centre of the ankle to calculate the mechanical axis of the limb. However, during navigated TKA, obese patients may be prone to errors due to difficulty in exposing, palpating and registering important bony landmarks such as the malleoli and the femoral epicondyles. Although several studies have validated the accuracy and consistency of computer-assisted navigation and have reported significant improvement in component orientation and limb alignment in TKA with computer navigation [7], [8], [9], [10], [11], [12], [13], [14], literature is lacking for limb and component alignment in computer-assisted TKA in the obese.
Accuracy of computer navigation during TKA in the obese has not been studied and whether computer navigation achieves the same degree of accurate limb and component alignment in the obese individuals vis-a-vis non-obese patients is not known. Hence, the purpose of the present study was to determine if computer navigation provides consistent accuracy for limb and component alignment during TKA irrespective of body mass index (BMI) by comparing limb and component alignment and the outlier rates in obese versus non-obese individuals undergoing computer-assisted TKA. Our hypothesis was that limb and component alignment will not be significantly different when obese and non-obese individuals were compared after computer-assisted TKA.
Section snippets
Patients and methods
We retrospectively reviewed the clinical and radiographic records of 1500 computer-assisted TKAs (in 1250 patients) performed between 2005 and 2009. Non-obese individuals were defined as those having a BMI of < 30 kg/m2 (calculated by dividing the subject's weight in kilogrammes by their height in metres squared), obese individuals were defined as those having a BMI of ≥ 30 kg/m2 and morbidly obese individuals were defined as those having BMI > 40 kg/m2. The inclusion criteria were primary
Results
Demographic and radiographic parameters in the non-obese, obese and morbidly obese groups are summarised in Table 1. Postoperatively, the limb alignment (mean HKA angle) was not significantly different when the non-obese group was compared with the obese group (p = 0.33) and when the non-obese group was compared with the morbidly obese group (p = 0.20). Although the postoperative coronal alignment of the femoral component was not significantly different when the non-obese group was compared to the
Discussion
Despite showing superior and consistent results in the restoration of limb and component alignment, the technical challenges during computer-assisted TKA in obese individuals remain. Obese patients may be prone to errors due to difficulty in registering the femoral head centre because of substantial weight of the leg and difficulty in registering the ankle centre due to difficulty in palpating the malleoli. Furthermore, excessive fat makes effective exposure difficult in the obese and excessive
Conflict of interest statement
The authors wish to state that no funds or benefits were received by any of the authors in support of this study/article from any source.
References (21)
- et al.
Total knee arthroplasty in obese patients: a comparison with a matched control group
J Arthroplasty
(2004) - et al.
Obesity and knee arthroplasty
Knee
(2007) - et al.
Comparison of limb and component alignment using computer-assisted navigation versus image intensifier-guided conventional total knee arthroplasty: a prospective, randomized, single-surgeon study of 467 knees
J Arthroplasty
(2007) - et al.
Computer assisted navigation in total knee arthroplasty: improved coronal alignment
J Arthroplasty
(2005) - et al.
Meta-analysis of alignment outcomes in computer-assisted total knee arthroplasty surgery
J Arthroplasty
(2007) - et al.
Does accurate anatomical alignment result in better function and quality of life? A prospective randomized controlled trial comparing conventional and computer-assisted total knee arthroplasty
J Arthroplasty
(2009) - et al.
Effect of body mass index on limb alignment after total knee arthroplasty
J Arthroplasty
(2013) - et al.
The influence of preoperative deformity on valgus correction angle: an analysis of 503 total knee arthroplasties
J Arthroplasty
(2013) - et al.
Tibial component failure mechanisms in total knee arthroplasty
Clin Orthop Relat Res
(2004) - et al.
Patient demographics as a predictor of the ten-year survival rate in primary total knee replacement
J Bone Joint Surg Br
(2003)
Cited by (18)
Robotic-Assisted Total Knee Arthroplasty in Obese Patients
2024, Arthroplasty TodayNavigated total knee arthroplasty: Retrospective study of 600 continuous cases
2021, Revue de Chirurgie Orthopedique et TraumatologiqueNavigated total knee arthroplasty: Retrospective study of 600 continuous cases
2021, Orthopaedics and Traumatology: Surgery and ResearchCitation Excerpt :In our study, sex, age and preoperative alignment had no impact on the results. Shetty et al. [21] found no difference in the implantation accuracy in obese versus normal-BMI patients with navigation. Conversely, Gaillard et al. [22] found that the positioning of the tibial component was less accurate in obese patients.
No influence of obesity on mid-term clinical, functional, and radiological results after computer-navigated total knee arthroplasty using a gap balancing technique
2021, Journal of Clinical Orthopaedics and TraumaCitation Excerpt :This can affect the size and position of the femur component which can influence the outcome. Therefore, with the rising number of obese patients, and paucity of literature on the influence of obesity on radiological2,27,28 and functional2,27 outcome after navigated TKA, the present study was done to a) determine if computer navigation provides consistent accuracy for limb and component alignment in obese sub-group of patients like in non-obese patients and b) to know if navigation achieves similar clinical and functional results in obese and non-obese patients when GB technique is used, at the end of 5 years after TKA. We prospectively studied the clinical, functional, and radiographic results of 187 consecutive computer-assisted TKAs performed between 2012 January and 2015 January, in 136 patients.
Clinical and radiographic outcomes of computer-navigated total knee arthroplasty are not adversely affected by body mass index
2020, Journal of OrthopaedicsCitation Excerpt :This further complicates the surgical management of such patients. However through the use of computer navigation, Shetty et al. reported that there was no significant difference in post-operative lower limb alignment between the obese and non-obese.8 Likewise, Yogeesh et al. reported that there was no significant difference in operating time with computer navigated knee arthroplasty between the obese and non-obese.9
- ☆
No benefits or funds were received in support of this study by any of the authors. This article is original and has not been published before or currently submitted to any other journal.