Anthropometric measurements of the knee: time to make it fit

Abstract

question in knee surgery is of course, should an implant be designed to accommodate 90 % of the population or should it cover the entire population. Early knee designs were developed "down the middle" using the mean sizes for males and females and as a result could not fit everyone perfectly.The mismatch of femoral components, especially in the mediolateral dimension of female patients, was one of the main reasons for the need to design specific implants in order to reduce component overhang in female patients [2,4,6]. Gender differences were also observed in the anatomy of the trochlear groove [9]. A strong correlation between the morphology of the proximal femur and the trochlea was reported by Wright et al. [10] in their paper.A meta-analysis on the outcome of TKA using gender implants was performed recently and showed that genderspecific TKA indeed reduces component overhang, but without any positive effect on clinical outcome [11].However, the functional evaluation of patients after TKA revealed an overall significant number of patients (regardless of gender) who presented with mediolateral overhang of either the femoral or tibial component. Bonnin et al.[1] reported on overhang for 66 % on the femoral side and 61 % on the tibial side. There was also a significant negative correlation between the overall overhang and clinical outcome. An overhang of the femoral component of more than 3 mm appears to be associated with an almost twofold increased risk of knee pain [7].One may presume that the mismatch between component design and bone morphology could have a significant impact on patient satisfaction. However, it remains unclear how much of a mismatch between the implant and the morphology of the knee might be tolerable as many other contributing factors might also have a significant impact on the clinical outcome as well.

The minimally invasive far medial subvastus approach for total knee arthroplasty in valgus knees

“…The most important finding of this study was that total knee arthroplasty for a fixed valgus knee could easily be performed via a minimally invasive far medial subvastus approach leading to fast functional recovery as observed by the Knee Society function score. This approach allows leaving the medial collateral attached to not further destabilize the valgus knee during its medial approach [3] therefore only asking for piecrust needling release on the concave and contracted side [36]. PS TKA could be used in all the patients without any laxity at one‐year follow‐up.…”

“…Patients were operated with the far medial subvastus approach and received a cemented fixed‐bearing PS total knee arthroplasty (Vanguard, Biomet, Warsaw, US). The deep MCL is in this approach released within the bursa and never further then the medial corner [36]. General anaesthesia with local infiltration analgesia was used in all cases.…”

Improving outcomes in total knee arthroplasty—do navigation or customized implants have a role?

“…Extra-clinical benefits, moreover, may not have yet been well defined for these technologies. The preoperative imaging of PSI, for example, can provide a wealth of anthropometric data for research purposes, in particular the rotational alignment of the distal femur [ 59 ]. Navigation similarly opens the door to an array of research, teaching, and surgical documentation opportunities.…”

Contemporary knee arthroplasty: one fits all or time for diversity?

“…A patient-specific rotation matches the original anatomy combined with a unique aspect ratio, guaranteeing perfect coverage. Already in 2014, an editorial entitled anthropometric measurements of the knee: time to make it fit [ 85 ] called for more implant variability. Last but not least, the slope of the tibia is different between the medial and lateral side with an intra-individual mean of > 2° and differences as high as > 9° [ 86 ].…”