ABSTRACT
INTRODUCTION: The purpose of this retrospective study was to study the effect of tibial implant design on the occurrence of radiolucent lines (RLLs) and aseptic loosening (AL) by comparing two different total knee arthroplasty (TKA) designs. MATERIALS AND METHODS: Two types of total knee arthroplasty, different for tibial shape, size and keel design were compared, 255 for the first and 774 for the second. The occurrence of RLLs and radiological signs of micro- and macro-mobility and aseptic loosening was analyzed. Demographic data were compared, as well as the type and rate of RLLs, occurrence of aseptic loosening and the presence of potential risk factors. RESULTS: The first implant design is morphometric and has a squarer keel than the second implant TKA. The overall rate of RLLs was similar (21% vs 23%), despite of a significantly lower rates of radiological signs of macro-mobility of the tibial component with the first implant (2% vs 17%). Survivorship of both designs was overall comparable (99.6% vs 98.8 %) the first implant group had more potential risk factors for poor bone quality than the second group (p < 0.05). CONCLUSION: A morphometric design is more anatomic and offers better bone coverage of the epiphyseal tibial surface. RLLs, as a sign of implant micro-mobility, were equally present in both designs. Radiological signs of macro-mobility at the metaphysis were less frequently observed in squared keel design. The morphometric implant did not show improved survivorship compared with a symmetric implant. LEVEL OF EVIDENCE: III.
Subject(s)
Arthroplasty, Replacement, Knee , Knee Prosthesis , Humans , Arthroplasty, Replacement, Knee/adverse effects , Retrospective Studies , Knee Prosthesis/adverse effects , Reoperation , Risk Factors , Prosthesis Design , Prosthesis Failure , Knee Joint/surgeryABSTRACT
BACKGROUND: The aim of this study was to evaluate total knee arthroplasty (TKA) radiographically to detect the occurrence of radiolucent lines (RLL) under the tibial base plate and to determine what type of RLL may have a correlation with aseptic loosening (AL). The study had two hypotheses: (1) RLLs may have different radiological aspects and evolutions in time depending of different factors (2) Signs of micro- and/or macro-mobility of the implant are necessary before diagnosing aseptic loosening of the tibial component. METHODS: Retrospective cohort study of 774 patients operated with a Vanguard TKA (Zimmer Biomet, Warsaw, IN, US) from 2007 to 2015. RLLs were recorded in a database and described according to their radiological aspect, localization, time of apparition, progression and eventual evolution to AL. Other collected parameters were pre- and post-operative HKA angles, amount of post-operative HKA correction, surgical, clinical and demographic data. RESULTS: 178/774 TKAs (23%) showed RLLs under the tibial base plate including 9 (1.2%) tibial implants needing revision for AL. Three different types and two aspects of RLLs were observed. Important deformity corrections or undercorrected implants were recognized as a mechanical risk factor for loosening. Elderly women with osteoporosis and young men with important pre-operative deformities were identified as clinical risk factors for RLLs. CONCLUSIONS: RLLs are frequently present at the epiphyseal bone/implant interface after total knee arthroplasty, but do not mean the implant is loose. They can be considered a sign of reduced epiphyseal surface fixation due to micro mobility of the tibial implant. Aseptic loosening can be observed radiologically when signs of macro-mobility of the implant are present at the metaphyseal level. LEVEL OF EVIDENCE: III.
Subject(s)
Arthroplasty, Replacement, Knee , Knee Prosthesis , Male , Humans , Female , Aged , Arthroplasty, Replacement, Knee/adverse effects , Knee Prosthesis/adverse effects , Retrospective Studies , Reoperation/methods , Risk Factors , Knee Joint/diagnostic imaging , Knee Joint/surgery , Prosthesis Failure , Prosthesis DesignABSTRACT
In this article we report the case of a 46-years-old Portuguese woman admitted in our orthopaedic ward with right knee pain. Radiological findings were consistent with neuroarthropathy. After exclusion of the most common causes of polyneuropathy, Familial amyloid polyneuropathy (FAP) was diagnosed by the discovery of a mutation V30M on chromosome 18 by polymerase chain reaction on a fibroblast culture of her skin biopsy. FAP is one of many aetiologies of polyneuropathy. Although a rare disease, genetic screening in selected populations makes early diagnosis and prompt treatment of asymptomatic family members readily available.
