Functional outcome of total knee replacement: a study protocol for a prospective, double-blinded, parallel-group randomized, clinical controlled trial of novel, personalized and conventional implants.

BACKGROUND: The development of total knee replacement (TKR) implant designs aims to improve outcome regarding pain, function, joint stiffness, instability, patellar problems, and ultimately wear of the implant. Recently, two major orthopaedic implant manufacturers launched a new generation of TKR implants which, according to the manufacturers, provide improved functional outcome. However, the benefits of these new TKR designs claimed by the manufacturers in terms of improved functional outcome still lack scientific documentation. The present randomized controlled trial has been designed to compare three fixed bearing, cemented cruciate-retaining (CR) designs; one of the new personalized TKR design with two conventional TKR designs with the main emphasis being on functional outcome. METHODS: The present study is a prospective, double-blinded, randomized, single-center intervention trial. A total of 240 patients will be recruited to participate in a parallel-group study at Coxa Hospital for Joint Replacement, Tampere, Finland. We will compare the short-term functional outcome of TKR performed with a novel personalized TKR design (Persona CR, Zimmer, Warsaw, IN, USA) against TKRs performed with two conventional designs (PFC CR, DePuy, Warsaw, IN, USA and Nexgen CR, Zimmer, Warsaw, IN, USA). In total, 80 patients will be randomized in each of the three study arms. The primary outcome in this study is the Oxford Knee Score (OKS), which is a validated patient-reported outcome measure (PROM). Secondary outcome measures include the Forgotten Joint Score, the 15D, the UCLA activity score, and the VAS pain scale. The results will be analyzed after 2-year follow-up. DISCUSSION: This paper presents a prospective, randomized, single-center trial study protocol. It provides details of patient randomization, PROMs, follow-up, methods of analysis of the material, and publication plan. An important aspect that will be considered in the study will be the economic effects of the novel designs as they are substantially more expensive, and the benefits of the added costs remain unknown. In addition, it is especially important to carry out evaluative studies in independent centers that are not biased by the interests of the manufacturers. TRIAL REGISTRATION: Retrospectively registered, November, 2017, ClinicalTrials.gov Identifier: NCT03339557 .

Total proximal tendon avulsion of the rectus femoris muscle.

Total proximal avulsions of the quadriceps femoris muscle group are rare injuries. Between the years 2001 and 2004 five patients with a total proximal avulsion of the tendon of the rectus femoris muscle were treated surgically in Mehiläinen Hospital in Turku, Finland. The median age of the patients was 21 years (range, 19-27) and the patients were all men. There were four soccer players and one hurdler. In all cases an avulsion of the proximal tendon of the rectus femoris muscle was confirmed by MRI. All of the patients were operated on and the delay from the injury to surgery ranged from 18 to 102 days. The result of the surgical treatment was rated good in all cases. All of the patients were able to return to their pre-injury level of activity 5-10 months after surgery. The median follow-up time was 20 months (range, 9-38). Surgical treatment of a total proximal avulsion of the tendon of the rectus femoris muscle seems to result in return to the pre-injury activity level in most cases.