Two surgical strategies are possible in total knee arthroplasty (TKA): a measured resection technique, in which bone landmarks are used to guide resections equal to the distal and posterior thickness of the femoral component, or a gap-balancing approach, in which equal collateral ligament tension in flexion and extension is sought before and as a guide to final bone cuts. In this study performed with computer assisted system, we compared the 2 different methods in 126 patients followed prospectively in order to analyze the effect of both the techniques on joint-line (JL) maintenance, axial limb restoration and components position. The gap technique showed a statistical increase in the post-operative value when compared with the measured resection technique, (P = 0.008). When comparing the two groups regarding to the pre-operative deformity, we have found a statistical difference (P = 0.001) in case of moderate pre-operative deformity (less than 10 degrees), and the measured resection technique showed a slight superiority in preserving a joint line more faithful to the pre-operative. We found an ideal alignment for the mechanical axis (180 degrees ± 3 degrees) (95% of cases). In six cases (5%), the mean post-operative value exceeded (varus or valgus) the ideal value by more than 3 degrees. In the frontal plane, a good alignment was observed for both femoral and tibial components without a significant difference between the two techniques. In the sagittal plane was found more alignment variability due to the different implants used and their ideal starting slope, from 7 degrees to 3 degrees. Finally, the surgeon can use the approach with which he has more confidence; however, as the measured resection technique causes less reduction in the post-operative joint-line position, in case of shortening of patellar tendon or patella infera, this technique is preferable.

Purpose The use of traditional cutting guides during knee arthroplasty in some cases could be extremely difficult, if not impossible, because of angular deformities, IM sclerosis, long-stemmed hip implants, or hardware within the femoral canal that cannot be removed. In these difficult cases navigation-assisted knee arthroplasty should be considered as an effective and appealing option. Methods We present 14 cases in which ideal mechanical and prosthetic alignment was achieved with different image-free, computer-assisted navigation systems, because of an extra-articular deformity (group A, nine patients) or because of a retained implant or hardware (group B, five patients).Results After a mean follow-up of 28 months (range 12-53 months), the average knee score increased overall from a mean of 33 points (range 12-63) to 78 points (range 63-90). The average functional score improved from a mean of 32 points (range 10-65) to 72 points (range 40-90). The postoperative mechanical axis ranged between 3°of varus and 3°of valgus. There was an implant revision in one patient who had a traumatic rupture of medial collateral ligament, which occurred 27 months after the index procedure.Conclusions Based on our results we think that the navigationassisted technique provides an alternative approach to the traditional instrumentation for treating these difficult patients in an effective and less invasive manner.

This retrospective study was done to evaluate the results of total knee arthroplasty performed on 32 patients with stiff knee, having a preoperative arc of movement between 0° and 50° (average 30°). This group of patients were matched with a group of 32 flexible knees, randomly selected from the same cohort of patients who underwent knee arthroplasty in our ward. At a mean follow-up of 4.5 years (min 2, max 11 years), seven patients of the stiff group reported complications (21.8% overall): four prosthetic infection that successively underwent removal of the implant, one skin necrosis 4 months after the intervention, one early contracture and one late stiffness of the knee. In the control group, in two cases, there was substitution of the implant due to periprosthetic infection. At the end of the study period, the clinical evaluation was not possible in four patients of the stiff and in two patients of the control group who underwent revision of the prosthetic components. An excellent or good clinical result was obtained in 92% of stiff group and in 96% of the control group patients. Although the final results achieved in these patients are worse than those of patients with flexible knee due to disadvantageous preoperative conditions and high complication rate, our results demonstrate the efficacy of the arthroplasty procedure as treatment of stiff knee.