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PURPOSE: The pediatric Simple Knee Value (pedi-SKV) is an outcome score in which paediatric patients are asked 'How would you rate your knee today as a percentage of normal (0% to 100% scale with 100% being normal)?'. The primary aim of this study was to validate the pedi-SKV by measuring its correlation with validated knee function scores used most often in paediatric orthopaedics. METHODS: This prospective study was conducted at a teaching hospital to evaluate the pedi-SKV's validity. A total of 44 paediatric patients (ten to 15 years old), were enrolled prior to anterior cruciate ligament reconstruction as well as 17 healthy controls. A survey form consisting of the Lysholm, International Knee Documentation Committee Pediatric Form (Pedi-IKDC) and pedi-SKV was given to subjects twice (enrolment and six months postoperatively). The criterion validity of the pedi-SKV was determined by correlating it to existing knee functional scores. Responsiveness to change was evaluated by comparing the pedi-SKV scores before and after surgery (enrolment visit and six-month postoperative visit). Discriminative ability was evaluated by comparing the pedi-SKV distribution in patients versus controls. RESULTS: There was a strong and significant correlation between the pedi-SKV and the Lysholm and Pedi-IKDC (p < 0.0001). The pedi-SKV had a good responsiveness to change (p < 0.0001 for the pedi-SKV before versus six months postoperatively). Like the other knee-specific functional sores (p < 0.0001), the pedi-SKV was able to distinguish between patients and controls (p < 0.0001). CONCLUSION: The pedi-SKV is a valid outcome measure that is strongly correlated with the Lysholm and Pedi-IKDC. This is a novel simple score that can be used by physicians in their daily practice. LEVEL OF EVIDENCE: II.
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INTRODUCTION: The number of hinged total knee arthroplasty (HTKA) procedures is constantly increasing. There are two hinge types: central (CHTKA) and posterior (PHTKA). The primary purpose of the study was to compare implant survival in patients with CHTKA versus PHTKA. The secondary purpose was to analyse the radiological and clinical results of the implants. HYPOTHESIS: There is no difference between the two groups. MATERIALS AND METHODS: This study involved 53 patients who received a HTKA for either primary, trauma or revision surgery, of these 32 were in the CHTKA group and 21 in the PHTKA group, with a mean age of 69 years (38-89). The exclusion criteria were: etiology of sepsis, incomplete records and refusal to use data. The revision rate, with the replacement of prosthetic components, was the primary endpoint. The secondary outcomes were: mobility, complications, VAS, IKS, Devane, Charnley and Oxford knee scores, and radiological progression. RESULTS: The mean follow-up was 51 months (1-139). At 60 months, overall survival rate of the HTKA was 81%, with a confidence interval (CI) of 95% (71-93.2), and there was no difference between CHTKA and PHTKA, 77.7% (95% CI, 63.3-95.4) versus 85.7% (95% CI, 72-100), p=0.625, respectively. Flexion was 101°±15 (80-140) for CHTKA versus 98°±12 (30-130) for PHTKA, p=0.006. VAS was 0.5±16 (0-6) for CHTKA versus 1.6±14 (0-4) for PHTKA, p=0.000008. The IKS was 103±39 (15-180) for CHTKA versus 81±51 (9-200) for PHTKA, p=0.03. There were no differences in either radiological progression, complications or other functional scores. DISCUSSION: No significant difference was observed between the survival of CHTKA and PHTKA. CHTKA had better flexion, reduced VAS and increased IKS. Surgeons should be aware of these findings and apply careful consideration to their choice of hinge. LEVEL OF EVIDENCE: IV; retrospective single-centre study.