Femoral intramedullary canal referencing is utilized by most of the total knee arthroplasty (TKA) systems. Violation of the canal is performed in order to engage rod instruments in the femoral diaphysis and to refer of the anatomical axis of the femur. Fat embolism, activation of the coagulation cascade, and bleeding may occur from the reamed femoral canal. The purpose of our study was to validate a new set of _minimally-invasive friendly_ instruments which allow to prepare the femur without violating the intramedullary canal. Twenty-five consecutive patients undergoing primary TKA through a mini-subvastus approach were enrolled in the study after informed consent had been obtained. Results of this cohort (group 1) were compared to another contemporary group (group 2) of 25 TKAs operated by the same surgeon using intramedullary instruments. The two groups were matched for gender, deformity, degree of arthritis, and surgical approach. Reliability of the new extramedullary set of instruments was first tested in ten cadaveric limbs. Preoperative long weight-bearing AP and lateral view of the knee were obtained taking care of neutral limb positioning. Template of the mechanical and anatomical axis were performed. Distal femoral resection was planned according to the template, and considering a bone cut perpendicular to the mechanical axis of the femur. Measurement from the template were reproduced on the distal femoral cutting jig. Flexion-extension control of the distal femoral resection was obtained using the anterior meta-diaphyseal cortex reference. Depth of resection, and varus-valgus angulation were selected according to the previous measurements and referring over the most prominent distal femoral condyle. A double check was performed using an extra-medullary rod referring two and a half finger-breaths medially to the antero-superior iliac spine. Postoperative blood loss, pain, swelling, functional recovery, and complications were recorded. Radiographic alignment was measured with long film. Mechanical axis was within 0±2° in 88% of group 1 and 84% of group 2 (p> 0.05). There were no difference between the two groups regarding the operative time. In group 1, postoperative blood loss (740 vs 820 mL) was reduced but this difference did not reach the statistical significance (p=0.07). No difference was found in terms of postoperative pain, knee swelling, and functional recovery. Extramedullary reference with careful preoperative templating can be safely utilized during total knee arthroplasty. Avoiding the violation of the femoral canal may enhance the benefits of a less invasive approach.

Opening wedge high tibial osteotomy (HTO) for varus knee osteoarthritis has shown several advantages over the classic closing wedge technique. The aim of the current prospective study was to evaluate mid-term clinical and radiographic results, as well as complications, of medial opening wedge osteotomy using the hemicallotasis technique. Forty-nine high tibial oste-otomies were performed for unilateral varus primary osteoarthritis from 1999 to 2002. A medial incomplete osteotomy was performed after elevating the superficial collateral ligament. Four pins were inserted, two hydroxyapatite-coated in the metaphyseal bone, and two standard conical pins in the diaphyseal bone. The correction started 4–5 days postoperatively. The patient managed the correction by adjusting half of a turn twice each day. When the desired correction was achieved, the device was locked. Eight-to-nine weeks after surgery, the radiographic healing was evaluated, and if adequate, the device was removed on a outpatient basis. The mean age of the patients was 57 years (range, 32–70 years). The mean follow-up was 5 years (range, 4–7 years). The mean hip-knee-ankle angle (HKA) was 167 (range 164–171) deg preoperatively and 182 (range, 176–186) deg at follow up. We did not observe any early or late collapse of the new bone wedge. Union was achieved in all patients, and the mean time to fixation was 69 (range 60–85) days. Knee Society score improved from 52 points preoperatively to 93 at follow up. Eighty-five percent of the patients showed excellent-to-good clinical outcome. None of the knees had required revision surgery at follow-up. No meta-diaphyseal mismatch was noted on both the sagittal and coronal plain at radiographic analysis. Patellar height (IS ratio) reduced, on average, from 1.1 (±0.4) to 0.9 (±0.4), but no patella was found to be baja. Complications included a number of superficial infection uneventfully healed such as two cellulitis with erysipelas-like rushes, and five minor (grade I-II) pin tract infections. There were two technical problems. One obese patient developed an undisplaced inter-condylar fracture of the proximal tibial osteotomized fragment, which subsequently healed and the patient achieved a good clinical outcome. In another patient the anterior pin on the metaphyseal fragment was positioned too anteriorly, and was thereafter repositioned. There were no neurologic or vascular complications. Using the hemicallotasis technique for HTO the authors obtained a precise correction with a relatively low complication rate. The use of an external fixator allowed quick surgery, early weight-bearing, immediate knee motion, avoiding permanent hardware on bone. Conversion to a total knee arthroplasty seems to be easy when this technique has been employed, but the influence of pin tract infection on possible septic failures remains to be determined.