The mid-term results of kinematic alignment (KA) for total knee arthroplasty (TKA) using image derived instrumentation (IDI) have not been reported in detail, and questions remain regarding ligamentous stability and revisions. This paper aims to address the following: 1) what is the distribution of alignment of KA TKAs using IDI; 2) is a TKA alignment category associated with increased risk of failure or poor patient outcomes; 3) does extending limb alignment lead to changes in soft-tissue laxity; and 4) what is the five-year survivorship and outcomes of KA TKA using IDI? A prospective, multicentre, trial enrolled 100 patients undergoing KA TKA using IDI, with follow-up to five years. Alignment measures were conducted pre- and postoperatively to assess constitutional alignment and final implant position. Patient-reported outcome measures (PROMs) of pain and function were also included. The Australian Orthopaedic Association National Joint Arthroplasty Registry was used to assess survivorship.Aims
Methods
The results of kinematic total knee arthroplasty (KTKA) have been reported in terms of limb and component alignment parameters but not in terms of gap laxities and differentials. In kinematic alignment (KA), balance should reflect the asymmetrical balance of the normal knee, not the classic rectangular flexion and extension gaps sought with gap-balanced mechanical axis total knee arthroplasty (MATKA). This paper aims to address the following questions: 1) what factors determine coronal joint congruence as measured on standing radiographs?; 2) is flexion gap asymmetry produced with KA?; 3) does lateral flexion gap laxity affect outcomes?; 4) is lateral flexion gap laxity associated with lateral extension gap laxity?; and 5) can consistent ligament balance be produced without releases? A total of 192 KTKAs completed by a single surgeon using a computer-assisted technique were followed for a mean of 3.5 years (2 to 5). There were 116 male patients (60%) and 76 female patients (40%) with a mean age of 65 years (48 to 88). Outcome measures included intraoperative gap laxity measurements and component positions, as well as joint angles from postoperative three-foot standing radiographs. Patient-reported outcome measures (PROMs) were analyzed in terms of alignment and balance: EuroQol (EQ)-5D visual analogue scale (VAS), Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS Joint Replacement (JR), and Oxford Knee Score (OKS).Aims
Patients and Methods
Many variables contribute to aseptic loosening, and the release of wear particles is a predominant source of late failure. It has been difficult to measure TKA wear quantitatively from retrieved devices; hence, there is a relative paucity of clinically observed TKA wear rates in the literature. Additionally, little is known about patient factors influencing wear rates. This study (a) establishes a clinically relevant TKA wear rate for a cruciate retaining TKA design and (b) relate those wear readings to gait measures of their hosts. 34 revision- and 11 postmortem-retrieved MG II tibial PE-components were included in the analysis. Wear scars on the articulating surface of the insert were digitized under light microscopy. The geometry of the surfaces was mapped at 100×100 μm using a low-incidence laser. Autonomous mathematical reconstruction of the original surface was used [1], and linear penetration on the medial and lateral surfaces and total wear volume were calculated (Fig-1). For five implants, gait data recorded during 1.5 years after surgery were available. Gait studies were performed using a three-dimensional optoelectronic system for motion capture. Joint kinematics and kinetics were calculated using a six-marker model of the lower extremity [2]. All knee moments are reported in Nm, acting externally at the tibia. Potential linear relationships between wear and moment characteristics were investigated.Introduction:
Methods:
A technical goal in total knee arthroplasty is the production of a neutral coronal plane mechanical axis. Errors may produce large mechanical axis deviations precipitating early implant failure. This study sought to test if measured distal femoral resection produced more accurate and consistent coronal alignment than arbitrarily set distal femoral resection. Data from a cohort of 255 consecutive unselected primary total knee arthroplasties undertaken by the senior author (PM) was collected prospectively and independently assessed. In the first 167 cases distal femoral resection was arbitrarily set to 5 degrees of valgus. In the remaining 88 cases the distal femoral resection angle was determined on a preoperative long leg standing AP radiograph. Postoperative coronal alignment was measured on long leg standing AP radiograph in all cases. The measured distal femoral valgus angle was between 4 and 7 degrees. An equal number measured either 5 or 6 degrees and accounted for 85% of the total number. Statistically insignificant improvements in mean axis and standard deviation were observed in the measured group: mean axis deviation −0.31 vs −0.51: p=0.17 (independent samples t test) and standard deviation 0.91 vs 1.09: p=0.055 (Levene test). Acceptable coronal alignment in total knee arthroplasty can reliably be obtained with conventional instrumentation. Improvement in standard deviation with measured distal femoral valgus angle approaches statistical significance.
Between December 1998 and December 1999 twenty-one patients with painful knee arthroplasties underwent assessment by radionuclide arthrography. There were eleven female and ten male patients, with an average age of 60 years at the time of the index procedure. The index procedure was a primary total knee arthroplasty, primary medial unicompartmental knee arthroplasty and revision medial UKA in seventeen, three and one patients respectively. Nineteen arthroplasties were uncemented and two were hybrids. All patients had previously been investigated by clinical examination, serological testing, fluoroscopic AP and lateral radiographs, and Tc99 bone scan with equivocal results. The presence of radionuclide about the tibial stem was considered diagnostic of tibial loosening. Nine patients underwent revision knee arthroplasty. The presence of radionuclide about the tibial stem correctly predicted a loose tibial component in four of five cases. Similarly, the absence of radionuclide about the tibial stem correctly predicted a stable tibial component in four of four cases. In the single misdiagnosed case the tibial component did not have a large central stem, had focal osteolysis about several screws, but remained stable. Radionuclide arthrogram is a useful tool in the investigation of painful knee arthroplasty. Radionuclide about the tibial stem is the key predictor of tibial component loosening.
This paper reports the authors’ experience of over 850 unicompartmental knee replacements beginning in 1985 with the MG2 uni and then the LCS uni in 1995, and more recently with the Allegretto, Oxford and PFC minimally invasive uni. Minimally invasive unicompartmental knee arthroplasty (MIU) offers the knee arthritis patient significant benefits compared with total knee arthroplasty. Some of these are especially important for Asian patients, in particular range of movement and ability to squat. The ideal indications for the MIU are not yet fully established but are becoming clearer. Contraindications are also clearer. These issues will be discussed in detail. The results in 100 cases of unicompartmental arthroplasty will be presented and discussed along with the complications in these patients. Special considerations and recommendations for the commencement of MIU will also be discussed. This recent and popular procedure also presents the knee surgeon with significant challenges. However, there are also disadvantages which will be outlined. The surgical technique of the MIU will be shown in detail. The paper closes on a brief discussion into recent developments by an 8 member international group of knee surgeons of a new MIU offering a choice of fixed or mobile bearing MIU, with precise instrumentation of both the femoral and tibial sides, and the early result of the first 18 procedures in 15 patients (3 bilateral).
