Nanohydroxyapatite-based bone graft substitute in tunnel enlargement after ACL surgery: RMN study.

BACKGROUND AND AIM: A successful anterior cruciate ligament reconstruction (ACL) requires solid healing of the tendon graft in the bone tunnel. New biological strategies have already been proposed with the aim of improving ACL graft healing and therefore allowing a faster rehabilitative program. The aim of this prospective study was to clinically and radiologically evaluate the efficacy of nanohydroxyapatite bone-base grafts in facilitating bone-tendon incorporation after ACL reconstruction with hamstrings (HS). As far as we know, this is the first study that has tried to asses the efficacy of such a type of bone substitute on human beings. MATERIALS AND METHODS: 40 male patients with chronic ACL rupture who underwent surgical reconstruction with 4-strand semitendinosus and gracilis tendon autograft via a single-bundle technique. Patients were randomly assigned to enter group A (20 patients, nanohydroxyapatite group) or group B (20 patients, control group). Preoperative and postoperative clinical evaluation was always performed, in a blinded way, assessing the Lachman and Pivot-shift tests and range of motion (ROM) of the affected knee. The Lysholm knee score, Tegner activity level, subjective and objective International Knee Documentation Committee (IKDC) forms, and 30 lb KT-1000 arthrometer evaluations. Patients underwent a magnetic resonance imaging (MRI) exam at 30, 90 and 180 days after surgery by the same musculoskeletal radiologist in a blinded way. RESULTS: As for the clinical evaluation, Lysholm, Tegner, IKDC scales, and KT-1000 arthrometer results did not show any significant difference between the two groups. Radiological data show a tendency toward better results in regard to the graft strength signal, the graftbone interface, and bone edema remodeling process, these parameters show significant differences between the two groups only at the short or mid-term follow-ups, while they are never significant at the mid-to long-term follow-up. CONCLUSIONS: In conclusion the use of nanohydroxyapatite bone substitute does not provide significant clinical improvements in terms of better knee stability or patient satisfaction.

Accuracy of manual instrumentation of tibial cutting guide in total knee arthroplasty.

PURPOSE: The aim of this study was to evaluate the accuracy of conventional instrumentation for tibial resection in total knee arthroplasty (TKA) as assessed by a computer-based navigation system during each phase of the surgical procedure. The hypothesis is that conventional instrumentation fails to achieve optimal accuracy in final implant positioning, thus leading to surgical errors. METHODS: Forty primary TKAs were performed. The resection guide was placed using an extramedullary guide. Accurate guide positioning was assessed by the navigation system prior to the osteotomy. The alignment measurement was repeated after resection and after component implantation in order to quantify the deviation caused by the manual positioning of the prosthetic components. A deviation ≥2° was considered unsatisfactory. RESULTS: In the frontal plane, unsatisfactory results observed were as follows: 15 % with reference to manual positioning of the resection guide and 10 % with reference to definition of the resection plane with a tendency towards varus malalignment. In the sagittal plane, unsatisfactory results were as follows: 45 % with reference to manual positioning of the resection guide and 40 % with reference to definition of the resection plane with a trend of decreased tibial slope angle. The deviation between bone resection and subsequent implant placement was ≥2° in none of the cases. CONCLUSIONS: The study confirms the hypothesis that conventional instrumentation fails to achieve optimal accuracy in the positioning of the tibial component. During each phase of the surgical procedure, a tendency towards varus malalignment and a decreased tibial slope angle were observed. LEVELS OF EVIDENCE: II.