Hip-Knee-Ankle Radiographs Are More Appropriate for Assessment of Post-Operative Mechanical Alignment of Total Knee Arthroplasties than Standard AP Knee Radiographs.

Weight-bearing hip-knee-ankle (HKA) radiographs are the gold standard for measuring lower limb alignment after total knee arthroplasty (TKA), however the majority of UK units use standardised anteroposterior (AP) knee radiographs. This study aimed to determine whether standardised AP knee radiographs adequately assess lower limb alignment after TKA. HKA radiographs from 50 post-operative TKAs were cropped to the size of a standardised AP knee radiograph allowing comparison of mechanical and anatomical alignment measurements between the two views. Repeatability of alignment measurements was significantly better for HKA radiographs, however, there was poor agreement of the mechanical alignment measured between the two views. Standardised AP knee radiographs are insufficient to assess the mechanical alignment of post-operative TKA and we recommend routinely using HKA radiographs.

Femoral nerve block for total knee replacement - a word of caution.

Femoral nerve block (FNB) is a well documented option for post-operative analgesia following major knee surgery. However, motor blockade may be prolonged preventing early mobilisation thereby increasing the length of stay. In addition, as a consequence of persistent quadriceps weakness, patients have an increased risk of falling. We present a series of five patients who underwent total knee replacement with spinal anaesthesia and FNB who fell, sustaining complete wound disruption - including a patient with peri-prosthetic fracture requiring further surgery and prolonged hospital stay. The literature, which is largely in anaesthetic journals, reflects the high quality of analgesia of FNB but makes little or no mention of the delays or dangers in early mobilization. We believe that the potential risks to orthopaedic patients are underestimated.