Promising short-term outcomes of free-hand burring technique to implant second-generation metaphyseal cone in Asian knees - a case series.

BACKGROUND: The second-generation metaphyseal cone was useful in managing bone defects in revision knee arthroplasty. However, due to the anatomical constraints in Asian osteometry, the authors utilized a novel free-hand burring technique instead of cannulated reaming for bone preparation. We reported the short-term outcomes of our surgical techniques specific to Asian osteometry. METHODS: We conducted a case series by consecutively recruiting 13 female and 12 male patients (involving 25 knees), with a mean age of 71 years (range, 54-88 years). The patients underwent revision total knee arthroplasty during the period from April 2017 to June 2022. Twenty-three tibial cones and 4 femoral cones using free-hand burring technique were implanted. The mean follow-up duration was 51 months (range 18-80 months). Due to the relatively small bone size and meta-diaphyseal center mismatch in the Asian knees, the free-hand burring technique instead of the cannulated reaming technique was adopted in preparing for cone implantation. The clinical outcomes were knee ranges of motion, the Knee Society Knee scores (KSS), end-of-stem pain, infection, and the need for revision surgery. The radiological outcomes included osteointegration, fracture, and loosening. RESULTS: Mean knee range of motion improved from 83 degrees (range 0°-120°) preoperatively to 106 degrees (range 60°-125°) postoperatively (P < 0.001). Mean KSS improved significantly from 29 (range 0-70) to 69 (range 5-100) (P < 0.001). All cones were osteointegrated. One case had transient end-of-stem pain, two developed intraoperative minor femoral fractures and one suffered from recurrent infection that did not require cone revision. Cone revision-free survivorship was 100%. There was no aseptic loosening. CONCLUSIONS: The second-generation cone implanted with free-hand burring bone preparation yielded promising short-term outcomes in Asian knees.

Is There an Inherent Risk to Damage the Popliteus Tendon by Femoral Component With Inbuilt External Rotation? A Pilot Study in Indian Knees.

INTRODUCTION: Femoral components with inbuilt rotation require thicker flexion resection of the lateral femoral condyle and could have a potential risk of damaging the popliteus tendon, especially in the smaller Asian knees. MATERIALS AND METHODS: We prospectively evaluated 10 patients with bilateral varus osteoarthritis knee to size the cuts and their location in relation to the popliteus tendon. Two different types of implant were used on either side; one side requires resection in 3° external rotation (group A) and the other side requires a femoral component with inbuilt external rotation (group B). We observed the incidence of injury to the popliteus tendon and distance between flexion cut to its attachment over the lateral femoral condyle between both groups. RESULTS: We had popliteus tendon injury in 3 knees all from group B. Risk of damaging the popliteus tendon was found higher in group B, as the distance between flexion cut to popliteus tendon attachment was significantly low. CONCLUSION: Femoral component with inbuilt external rotation has more risk of injuring the popliteus tendon because flexion cut takes out more bone from the lateral femoral condyle.