Study On Morphological Features Of Proximal Tibial Resected Surface In Total Knee Arthroplasty Of Chinese Adults

Along with constant generalization and application of total knee arthroplasty (TKA), substantial progress had been achieved in the design of knee prosthesis and the surgery skill abroad. More and more surgeons and patients began to take TKA as alternative in the clinical practice in China. However, most imported knee prosthesis used for Chinese population were designed according to the anatomical characteristics of western population. No total knee prosthesis system had been developed in China recently.The tibial baseplates sometimes could not provide enough coverage for the reseted surface perfectly after the resection of proximal tibia in TKA. Besides the technical factors, difference of anatomical characteristics of proximal tibial between western and Chinese population might be the primary reason which leaded to the mismatching of resected surface of proximal tibia and tibial baseplates in TKA. Reports on the anatomical features of Asia knees comparing with western knees were found in the literatures. The problems would appear when the imported total knee prosthesis are applied to Chinese population.Therefore, the objective of this study was to obtain the morphological data of resected surface of proximal tibia in Chinese adults and explore the difference of morphological characteristics between the knees of Chinese adults and imported tibial prosthesis commonly used in internal markets, which would provide practical reference for the database of Chinese knees and design of tibial baseplate according to the anatomical characteristics of proximal tibia of Chinese adults. ObjectiveTo provide reference for database of Chinese knees and designing the tibial baseplates of total knee prosthesis for Chinese population, the datum of size and shape on proximal tibia were obtained by anthropometric measurements of proximal tibia on the level of resected surface in TKA.Methods1. 90 adults including 45 males and 45 females who had disorders of monolateral keens were recruited from our Orthopaedic Clinics according to different height groups from January 2006 to September 2006. All the male and female patients were averagely devided into three groups (groupⅠ: 151～160cm,groupⅡ:161～170cm,groupⅢ:171～180cm) according to their heights.The mean age was 30.7 yrs. (range from 18 to 50yrs.).2. The normal knee of each patient was fixed on the brace ensuring its extension and neutral position and scaned by CT (Computer Tomography). The three-dimensional solid models of normal knees were reconstructed by standard mode on CT work station.3. The CT transver films on the level 10mm below the lateral tibial plateau with different degree of posterior inclination (0,3,6,9,12deg) on sagittal plane were obtained.4. Anthropometric measurements of several parameters (Anteroposterior and Mediolateral dimension of resected surface, AP/ML ratio of resected surface, AP and ML dimension of medial and lateral resected surface) were performed by using computer-aided design soft (AutoCAD 2006).5. The correlations of the parameters were analyzed by statistics softs(SPSS13.0 and SAS8.0). Meanwhile, we compared the datas of tibial resected surface with several commonly imported tibial baseplates of total knee prosthesis.Results 1. The shape of proximal tibial resected surface were asymmetric ,and the AP dimension and ML dimension of medial resected surface were longer than the dimensions of lateral resected surface (P<0.05).2. The features of height and sex of individuals had impacts on AP, ML dimension and AP/ML ratio (P<0.05). With increase of height, the AP and ML dimension increased and AP/ML ratio decreased (P<0.05).3. With the posterior inclination degree inceasing the AP/ML ratio decreased too (P<0.05).4. The AP dimension of resected surface were correlated positively with ML dimension of resected surface(r=0.942, P<0.05) , and AP/ML ratio of resected surface showed negative correlation with ML dimension of resected surface(r=-0.607, P<0.05). That meaned AP/ML ratio of proximal tibial resected surface of population with small stature was larger than those with large sature.5. There were significant differences about AP and ML dimesions of proximal tibial resected surface between males and females in the same group of height (P<0.05), hower, no significance about AP/ML ratios (P>0.05).6. The AP/ML ratio of proximal tibial resected surface of Chinese population was larger than those of several commonly imported tibial baseplates of total knee prosthesis.ConclusionThe morphogy of resected surface of proximal tibia had obvious feature. Presently the imported tibial baseplates of total knee prosthesis commonly used could not cover proximal tibial resected surface of Chinese population perfectly.The AP/ML ratio should be appropriately raised while designing the tibial baseplates of total knee prosthesis for Chinese population.