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Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_4 | Pages 9 - 9
1 Mar 2021
To K Khan W
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The current standard of practice following knee arthroplasty is to demonstrate the appropriate alignment of knee replacements using knee radiographs. Recent studies have suggested that standard knee radiographs provide adequate accuracy for tibial prosthesis alignment assessment as compared with long knee view radiographs which are more technically demanding and carry greater radiation exposure. In this study, we aim to address whether alignment measured on standard knee radiographs are reliable and reproducible over time. We examined a cohort of 80 patients 37 male (46%), 43 females (54%), mean age = 68 years) who underwent total knee arthroplasty (TKA). Standard knee anteroposterior radiographs performed within 2 days following surgery were compared to standard knee anteroposterior radiographs taken 1 year following the surgery in patients with well-functioning prosthesis. Tibial prosthesis alignment angles between the longitude of the tibial shaft and the tibial baseplate were calculated using Centricity Enterprise Web V3.0 software. The data was examined using R software. In well-functioning primary knee arthroplasties, tibial prosthesis alignment angles measured in the 1-year follow-up standard view knee radiographs were found to deviate from measurements obtained with the same radiographic specifications in the immediate post-operative period. A significant mean percentage difference was found between the two radiographs. Long knee view radiographs may be required in order to accurately assess tibial prothesis alignment following total knee arthroplasty


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_2 | Pages 29 - 29
1 Mar 2021
Dalal S Aminake G Chandratreya A Kotwal R
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Abstract. Introduction. Long term survivorship in Total Knee Arthroplasty is significantly dependent on prosthesis alignment. The aim of this study was to determine, compare and analyse the coronal alignment of the tibial component of a single implant system using 3 different techniques. Method. Retrospective study of cases from a prospectively collected database. Radiological assessment included measurement of the coronal alignment of tibial components of total knee arthroplasties, and its deviation from the mechanical axis. A comparison study of intramedullary, extramedullary and tibial crest alignment methods was performed. Results. 66 consecutive patients (3 groups of 22 each). Mean BMI was 26. The mean angle of deviation from the mechanical axis was significantly lesser (p< 0.05) in the Tibial crest alignment group patients compared to the other 2 groups. Moreover, the number of outliers (+/-3 degrees) were 2 and 4 in the intra and extramedullary group, whereas there were none in the tibial crest group. The inter and intraclass correlation coefficient was 0.8 and 0.9 respectively. Conclusion. The Tibial Crest Alignment Technique is an effective technique to produce consistent results to achieve optimal coronal alignment of the tibial component in TKA, even in patients with high BMI. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXVIII | Pages 42 - 42
1 Jun 2012
McKenna R Latif A McLeery M Chambers M Rooney B Leach W
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We aim to compare post-operative length of stay and cardiopulmonary morbidity in patients randomised to either navigated or conventional total knee arthroplasty (TKA). Patients undergoing primary TKA for osteoarthritis were prospectively assigned randomly to either navigation-guided or control groups and blinded to this. All patients received a PFC implant (DePuy, Warsaw, IN). In the control group the standard femoral intramedullary and tibial extramedullary alignment rod was used. In the navigation group, the BrainLab (Munich, Germany) navigation system was used. All operations were carried out by one of two consultant orthopaedic knee surgeons. Length of post operative hospital stay and the development of cardiopulmonary complication were recorded and groups compared. 100 patients were recruited (55 control vs 45 navigated). Patient demographics were similar in both groups. Mean length of stay was 7 days in the control group (range 3-101), 5 days in the navigation group (range 3-10). The mode was 4 days in both groups. 7 patients (13%) stayed for >7 days in the control group, 3 patients (7%) stayed >7 days in the navigation group(p=0.339). 4 patients(7%) required >10 days inpatient stay in the control group, 0 patients required to stay in hospital for longer than 10 days in the navigation group(p=0.069). The causes for the length of stay exceeding 10 days were pulmonary embolus in 3 patients, and chest infection in 1 patient. Patients undergoing navigation-guided TKA required shorter post-operative inpatient stays than those undergoing arthroplasty using conventional techniques. Fewer patients in the navigation group required stays longer than 7 or 10 days. The difference in post-operative stay was associated with fewer respiratory complications in the navigated group


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 5 - 5
1 Jul 2014
Porter A Snyder B Franklin P Ayers D
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Summary Statement. A prospective randomised evaluation of primary TKA utilizing patient specific instruments demonstrated great accuracy of bone resection, improved sagittal alignment and the potential to improve functional outcomes and reduce operating room costs when compared to standard TKA instrumentation. Introduction. Patient specific instruments (PSI), an alternative to standard total knee arthroplasty (TKA) technology, have been proposed to improve the accuracy of TKA implant placement and post-operative limb alignment. Previous studies have shown mixed results regarding the effectiveness of PSI. The purposes of this study were (1) to evaluate the accuracy of the pre-operative predicted PSI plan compared to intra-operative TKA resection measurements, (2) to compare patient-reported outcome measures of PSI and standard TKA patients, and (3) to compare the incremental cost savings with PSI. Patients and Methods. This randomised, prospective pilot study of 19 patients undergoing primary TKA with a cruciate-retaining cemented prosthesis (NexGen, Zimmer Inc.) was conducted by a single high-volume arthroplasty surgeon (DCA). Patients were randomised to PSI or standard instrumentation. Patients randomised to the PSI cohort received a pre-operative knee MRI for PSI fabrication using Zimmer proprietary software. 10 standard TKA and 9 PSI TKA were completed. Pre-operative baseline SF-36 and WOMAC scores were collected. Operative data collected included operating room times, implant details, femoral (medial/lateral distal and posterior) and tibial (medial/lateral) cut thicknesses, and number of instrument trays used. Hospitalization data collected included length of stay, blood loss, drain output, and transfusion requirements. Follow-up occurred at 2 weeks, 6–8 weeks, 3 months, 6 months, and 1 year, with SF-36 and WOMAC scores collected at each time point. Routine radiographic analysis was carried out in both cohorts. Extensive financial data was collected including costs of operating room use and anesthesia, implants, and hospitalization. Statistical analyses included t-tests for continuous variables and chi-square tests for categorical variables. Results. All femoral and tibial implant sizes used during TKA matched the component sizes predicted by the PSI software. Flexion gap bone resection (posterior medial/lateral femoral cuts) was extremely accurate (<1 mm on average) when compared with PSI predictions. PSI proximal tibial bone resection was also extremely accurate and within 1 mm on average of predicted values. Sagittal plane tibial component posterior slope in PSI TKA was significantly more accurate (7.33 degrees) in comparison to standard instrumentation (4.20 degrees) (p<0.025). No significant differences in coronal mechanical limb alignment existed between the two cohorts (p>0.05). There were no differences in operating room times, length of stay, or transfusions between the two groups. PSI patients used 4 fewer instrument trays per case (p<0.0001). There were no significant differences in functional outcome scores between the two groups (p>0.05). Discussion/Conclusion. PSI TKA demonstrated outstanding accuracy in bone resection when compared with the custom operative plan. There was no difference in post-operative coronal limb alignment or individual component alignment between the two groups, but an improvement in tibial component alignment in the sagittal plane in the PSI cohort was statistically significant. The number of instrument trays in PSI TKA's were significantly less than standard TKA which led to less cost for instrument sterilization and assembly, and quicker room set-up. PSI instrumentation resulted in accurate bone resection and appropriate limb and component alignment after primary TKA in this prospective randomised evaluation


Objectives

Preservation of both anterior and posterior cruciate ligaments in total knee arthroplasty (TKA) can lead to near-normal post-operative joint mechanics and improved knee function. We hypothesised that a patient-specific bicruciate-retaining prosthesis preserves near-normal kinematics better than standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining prostheses in TKA.

Methods

We developed the validated models to evaluate the post-operative kinematics in patient-specific bicruciate-retaining, standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under gait and deep knee bend loading conditions using numerical simulation.