Aims. While mechanical alignment (MA) is the traditional technique in total knee arthroplasty (TKA), its potential for altering constitutional alignment remains poorly understood. This study aimed to quantify unintentional changes to constitutional coronal alignment and
Aims. The Coronal Plane Alignment of the Knee (CPAK) classification is a simple and comprehensive system for predicting pre-arthritic knee alignment. However, when the CPAK classification is applied in the Asian population, which is characterized by more varus and wider distribution in lower limb alignment, modifications in the boundaries of arithmetic hip-knee-ankle angle (aHKA) and
The aim of mechanical alignment in total knee arthroplasty is to align all knees into a fixed neutral position, even though not all knees are the same. As a result, mechanical alignment often alters a patient’s constitutional alignment and
Aims. The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral. Methods. The study involved 945 TKAs, which were performed in 641 patients with primary OA, between January 2000 and January 2009. These were classified into 12 phenotypes based on the combined assessment of four categories of the arithmetic hip-knee-ankle angle and three categories of actual
Aims. Medial unicompartmental knee arthroplasty (UKA) is undertaken in patients with a passively correctable varus deformity. Our hypothesis was that restoration of natural soft tissue tension would result in a comparable lower limb alignment with the contralateral normal lower limb after mobile-bearing medial UKA. Patients and Methods. In this retrospective study, hip-knee-ankle (HKA) angle, position of the weight-bearing axis (WBA) and knee
Abstract. Introduction. Coronal plane alignment of the knee (CPAK) classification utilises the native arithmetic hip-knee alignment to calculate the constitutional limb alignment and
The December 2023 Knee Roundup. 360. looks at: Obesity is associated with greater improvement in patient-reported outcomes following primary total knee arthroplasty; Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?; Robotic or manual total knee arthroplasty: a randomized controlled trial; Patient-relevant outcomes following first revision total knee arthroplasty, by diagnosis: an analysis of implant survivorship, mortality, serious medical complications, and patient-reported outcome measures using the National Joint Registry data set; Sagittal alignment in total knee arthroplasty: are there any discrepancies between robotic-assisted and manual axis orientation?; Tourniquet use does not impact recovery trajectory in total knee arthroplasty; Impact of proximal tibial varus anatomy on survivorship after medial unicondylar knee arthroplasty; Bone cement directly to the implant in primary total knee arthroplasty?; Maintaining
Aims. 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?. Methods. 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. Results. The postoperative HKA distribution varied from 9° varus to 11° valgus. All PROMs showed statistical improvements at one year (p < 0.001), with further improvements at five years for Knee Osteoarthritis Outcome Score symptoms (p = 0.041) and Forgotten Joint Score (p = 0.011). Correlation analysis showed no difference (p = 0.610) between the hip-knee-ankle and joint line congruence angle at one and five years. Sub-group analysis showed no difference in PROMs for patients placed within 3° of neutral compared to those placed > 3°. There were no revisions for tibial loosening; however, there were reports of a higher incidence of poor patella tracking and patellofemoral stiffness. Conclusion. PROMs were not impacted by postoperative alignment category. Ligamentous stability was maintained at five years with
Abstract. Introduction. Osteotomy is recognised treatment for osteoarthritis of the knee. Evidence suggests favourable outcomes when compared to arthroplasty, for younger and more active individuals[1]. Double level osteotomy (DLO) is considered when a single level is insufficient to restore both
Introduction. While implant designs and surgical techniques have improved in total knee arthroplasty (TKA), approximately 20% of patients remain dissatisfied. The purpose of this study was to determine if reproduction of anatomic preoperative measurements correlated to improved clinical outcomes in TKA. Methods. We retrospectively reviewed95 patients (106 knees) who underwent a TKA between 2012 −2013 with a minimum of one year follow-up. All patients had a pre and post-operative SF-12 and WOMAC scores. Pre and 6 week post-operative radiographs were reviewed to compare restoration of coronal plane alignment, maintenance of
Abstract. Introduction. Double-level knee osteotomy (DLO) is a challenging procedure that requires precision in preoperative planning and intraoperative execution to achieve the desired correction. It is indicated in cases of severe varus or valgus deformities where a single-level osteotomy would yield significantly tilted
Aims. A comprehensive classification for coronal lower limb alignment with predictive capabilities for knee balance would be beneficial in total knee arthroplasty (TKA). This paper describes the Coronal Plane Alignment of the Knee (CPAK) classification and examines its utility in preoperative soft tissue balance prediction, comparing kinematic alignment (KA) to mechanical alignment (MA). Methods. A radiological analysis of 500 healthy and 500 osteoarthritic (OA) knees was used to assess the applicability of the CPAK classification. CPAK comprises nine phenotypes based on the arithmetic HKA (aHKA) that estimates constitutional limb alignment and
The Coronal Plane Alignment of the Knee (CPAK) is a recent method for classifying knees using the hip-knee-ankle angle and
Abstract. Background. Little scientific evidence is available regarding the effect of knee
Background. Surgical planning of long bone surgery often takes place using outdated 2D axes on 2D images such as long leg standing X-rays. This leads to errors and great variation between intra- and inter- observers due to differing frames of reference. With the advent of 3D planning software, researchers developed 3D axes of the knee such as the Flexion Facet Axis (FFAx) and Trochlear Axis (TrAx), and these proved easy to derive and reliable. Unlike 2D axes, clinicians and scientists can use a single 3D axis to obtain measurements relative to other 3D axes, in all three planes Deriving a 3D axis also does not require an initial frame of reference, such as in trying to derive the 2D Posterior Condylar Axis (PCAx), whereby a slight change in slice orientation will affect its position. However, there is no 3D axis derived for the tibial plateau yet. Measurements of tibial
Introduction. The constitutional knee anatomy in the coronal plane includes the distal femoral
Aims. The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery. Methods. An analysis of 38 patients who underwent TKA and 32 who underwent bi-UKA was performed as a secondary study from a prospective, single-centre, randomized controlled trial. CT imaging was used to measure coronal, sagittal, and axial alignment of the knee preoperatively and at three months postoperatively to determine changes in anatomy that had occurred as a result of the surgery. The hip-knee-ankle angle (HKAA) was also measured to identify any differences between the two groups. Results. The pre- to postoperative changes in joint anatomy were significantly less in patients undergoing bi-UKA in all three planes in both the femur and tibia, except for femoral sagittal component orientation in which there was no difference. Overall, for the six parameters of alignment (three femoral and three tibial), 47% of bi-UKAs and 24% TKAs had a change of < 2° (p = 0.045). The change in HKAA towards neutral in varus and valgus knees was significantly less in patients undergoing bi-UKA compared with those undergoing TKA (p < 0.001). Alignment was neutral in those undergoing TKA (mean 179.5° (SD 3.2°)) while those undergoing bi-UKA had mild residual varus or valgus alignment (mean 177.8° (SD 3.4°)) (p < 0.001). Conclusion. Robotic-assisted, cruciate-sparing bi-UKA maintains the natural anatomy of the knee in the coronal, sagittal, and axial planes better, and may therefore preserve normal joint kinematics, compared with a mechanically aligned TKA. This includes preservation of coronal
Since 2005, the author has performed nearly 1000 Oxford medial unicompartmental arthroplasties (UKA) using a mobile bearing. The indications are 1) Isolated medial compartment osteoarthritis with ‘bone-on-bone’ contact, which has failed prior conservative treatment, 2) Medial femoral condyle avascular necrosis or spontaneous osteonecrosis, which has failed prior conservative treatment. Patients are recommended for UKA only if the following anatomic requirements are met: 1) Intact ACL, 2) Full thickness articular cartilage wear limited to the anterior half of the medial tibial plateau, 3) Unaffected lateral compartment cartilage, 4) Unaffected patellar cartilage on the lateral facet, 5) Less than 10 degrees of flexion deformity, 6) Over 100 degrees of knee flexion, and 7) Varus deformity not exceeding 15 degrees. Exclusion criteria for surgery are BMI of more than 30, prior high tibial osteotomy, and inflammatory arthritis. All cases were performed with a tourniquet inflated using a minimally-invasive incision with a quadriceps-sparing approach. Both femoral and tibial components were cemented. Most patients were discharged home the next morning; bilaterals usually stayed a day longer. We have previously described our results and the factors determining alignment. In a more recent study, we have compared the coronal post-operative limb alignment and knee
Since 2005, the author has performed 422 Oxford medial unicompartmental arthroplasties (UKA) using a mobile bearing. There were 263 females and 119 males, (40 patients had bilateral UKAs) with a mean age of 62 years. The indications were: Isolated medial compartment osteoarthritis with ‘bone-on-bone’ contact, which had failed prior conservative treatment; Medial femoral condyle avascular necrosis or spontaneous osteonecrosis, which had failed prior conservative treatment. Patients were recommended UKA only if the following anatomic requirements were met: Intact ACL, Full thickness articular cartilage wear limited to the anterior half of the medial tibial plateau, Unaffected lateral compartment cartilage, Unaffected patellar cartilage on the lateral facet, Less than 10 degrees of flexion deformity, Over 100 degrees of knee flexion, Varus deformity not exceeding 15 degrees. Exclusion criteria for surgery were BMI of more than 30, prior high tibial osteotomy, and inflammatory arthritis. All cases were performed with a tourniquet inflated using a minimally-invasive incision with a quadriceps-sparing approach. Both femoral and tibial components were cemented. Rehabilitation consisted of teaching the patients 6 exercises to regain strength and range of motion, and weight-bearing as tolerated with a cane began from the evening of surgery. Most patients were discharged home the next morning; bilaterals usually stayed a day longer. We have previously described our results and the factors determining alignment. In a more recent study we have compared the coronal postoperative limb alignment and knee
Patients presenting with arthrosis following high tibial osteotomy (HTO) pose a technical challenge to the surgeon. Slight overcorrection during osteotomy sometimes results in persisting medial unicompartmental arthrosis, but with a valgus knee. A medial UKA is desirable, but will result in further valgus deformity, while a TKA in someone with deformity but intact cruciates may be a disappointment as it is technically challenging. The problem is similar to that of patients with a femoral malunion and arthrosis. The surgeon has to choose where to make the correction. An ‘all inside’ approach is perhaps the simplest. However, this often means extensive release of ligaments to enable ‘balancing’ of the joint, with significant compromise of the soft tissues and reduced range of motion as a consequence. As patients having HTO in the first place are relatively high demand, we have explored a more conservative option, based upon our experience with patient matched guides. We have been performing combined deformity correction and conservative arthroplasty for 5 years, using PSI developed in the MSk Lab. We have now adapted this approach to the failed HTO. By reversing the osteotomy, closing the opening wedge, or opening the closing wedge, we can restore the obliquity of the joint, and preserve the cruciate ligaments. Technique: CT based plans are used, combined with static imaging and on occasion gait data. Planning software is then used to undertake the arthroplasty, and corrective osteotomy. In the planning software, both tibial and femoral sides of the UKA are performed with minimal bone resection. The tibial osteotomy is then reversed to restore
Introduction. Although total knee replacement became a widespread procedure for the purpose of knee reconstruction, osteotomies around the knee were regularly performed. Total knee arthroplasty should be performed for advanced arthritis of the knee. With the advent of biplanar open wedge high tibial osteotomy (HTO) combined with locking plate fixation, HTO has been expanded and its surgical outcome has been improved in recent years. However, post-operative joint-line obliquity has been raised as a concern with this procedure, which may affect the outcome especially in the knees with severe varus deformity. Hence the purpose of this study is to analyze the compression and shear stresses in the knee cartilage with
Introduction. Osteotomy for medial gonarthrosis is most often done as a proximal tibial valgus osteotomy, either as a closing wedge osteotomy (HTO) or as an opening wedge osteotomy including hemicallostasis (HCO). In case of lateral gonarthrosis the osteotomy is done as a proximal tibial varus osteotomy, closing or opening wedge or as a distal femoral varus osteotomy depending on the anatomy of the knee. The early period after osteotomy is influenced by complications to osteotomy. Complications depend on the operative method and localisation of surgery. Short- and long-term results are presented as knee scores or survivorship of high tibial osteotomy. Most often used scores are the HSS-score, NHP-score and the knee scores according to Lysholm and Tegner. Scores from the patient’s perspective are NHP, SF-36. KOOS (Knee Injury and Osteoarthritis Outcome Score) was introduced recently, and only short-term results are available. Results. Osteotomy for medial gonarthrosis. Immediate postoperative results. The closing wedge osteotomy is the golden standard and reported complications are peroneal palsy in 0 – 8%, infection in 1 – 3%, fracture of the tibial plateau and delayed union in 3 – 5% and thromboembolism in 2 – 4%. When the opening wedge method including HCO is used peroneal palsy is extremely seldom, delayed union is reported in 2%, major pin-tract infection in 2 – 20 % and thromboembolism in 2 – 4%. Short-term results. The short-term results are generally good and one to two years after osteotomy excellent and good results are reported in 85 – 97 %. All five partial scales in KOOS with the exception of sports/ recreation function were significantly improved 3 – 4 months postoperatively. Long term results 5 – 20 years after surgery. Evaluations of osteotomies using survivorship of the osteotomy, with conversion to a total knee as the endpoint, show an expected rate of survival of 73–94% at 5 years, 51–85 % at ten years, 39–68 % at 15 years and 30% at 20 years. Analysis of risk factors show that age older than 50 years, presence of lateral tibial thrust and insufficient valgus correction were significantly associated with probability of early failure. Evaluations using knee scores with a mean follow-up time of 5 – 10 years show excellent and good result in 64 – 80%. At follow-up 11– 15 years after surgery the fraction good and excellent knees is 55 – 60% and 16– 20 years after osteotomy a minority of the knees are good or excellent, at most 46%. Stage of arthrosis: Good long-term results are reported for knees with early medial arthrosis with at most obliteration of the medial joint space or just minimal bone attrition. Results after HCO on knees with more advanced gonarthrosis are reported with a short follow-up and the change of osseous correction after osteotomy was less compared to HTO. Only minimal progress of arthrosis after osteotomy is reported in most papers. The results of some studies indicate that the greater the surgical correction, the slower the progress of the medial joint arthrosis. Alignment of the knee:. Most reports find better clinical results and less risk for failure when the osteotomy is corrected to a slight over-correction of the knee alignment. There is however no consensus on the smallest correction needed to change the load on the medial arthrotic compartment. Osteotomy for lateral gonarthrosis. The condition is uncommon and a minority of the papers on osteotomy for gonarthrosis concern osteotomy for lateral gonarthrosis. The aim of osteotomy for lateral gonarthrosis is to achieve a varus alignment of the knee with a
Background:. It has been suggested that double-level osteotomy can prevent the occurrence of
Introduction. Soft tissue balancing in total knee arthroplasty surgery may prove necessary to elevate patient satisfaction and functional outcome beyond the current fair average. A new generation of contact load sensors embedded in trial tibial liners provides quantification of loads, direction, and an indirect assessment of ligamentous tension. With this technology, quantified intra-operative balancing may potentially restore compartmental load distribution to a more physiological and functional degree. Objective. 1). To define a clinically useful target zone for balancing of the soft tissue envelope of knees at the time of surgery using numerical data from load sensors in tibial liner trial components. 2). To validate the boundaries of the target zone on a medial v. lateral contact load scatterplot with PROMs. Method. This study is a prospective IRB approved clinical study of 104 patients (112 knees) from a single surgeon. The intra-operative balancing aim was the restoration of a physiological compartmental load distribution, defined as less than 15 pounds of load differential between the medial and lateral compartments throughout flexion. This was performed using an algorithmic method of soft tissue releases combined with minor
Introduction. The mechanical classical method of knee surgical instrumentation by alignment is based on built-in compromises and is considered insufficient to ensure consistent success. Soft tissue balancing is thus now seen as necessary for optimal functional outcomes and patient satisfaction. (Matsuda 2005, Winemaker 2002). The authors have previously demonstrated that balancing can be achieved through specific strategic moves. In this study, the goal was to determine the efficacy of a given surgical algorithm and to define predictors of improved outcome. The surgical target is equilibrium of contact loads. The mechanical axis remains in neutral, however subtle variation in the
Limb deformity is common in patients presenting for knee arthroplasty, either related to asymmetrical wear patterns from the underlying arthritic process (intra-articular malalignment) or less often major extra-articular deformity due to prior fracture malunion, childhood physical injury, old osteotomy, or developmental or metabolic disorders such as Blount's disease or hypophosphatemic rickets. Angular deformity that is above the epicondyles or below the fibular neck may not be easily correctable by adjusted bone cuts as the amount of bone resection may make soft tissue balancing impossible or may disrupt completely the collateral ligament attachments. Development of a treatment plan begins with careful assessment of the malalignment which may be mainly coronal, sagittal, rotational or some combination. Translation can also complicate the reconstruction as this has effects directly on location of the mechanical axis. Most intra-articular deformities are due to the arthritic process alone, but may occasionally be the result of intra-articular fracture, periarticular osteotomy or from prior revision surgery effects. While intra-articular deformity can almost always be managed with adjusted bone cuts it is important to have available revision type implants to enhance fixation (stems) or increase constraint when ligament balancing or ligament laxity is a problem. Extra-articular deformities may be correctable with adjusted bone cuts and altered implant positioning when the deformity is smaller, or located a longer distance from the joint. The effect of a deformity is proportional to its distance from the joint. The closer the deformity is to the joint, the greater the impact the same degree angular deformity will have. In general deformities in the plane of knee are better tolerated than sagittal plane (varus/valgus) deformity. Careful pre-operative planning is required for cases with significant extra-articular deformity with a focus on location and plane of the apex of the deformity, identification of the mechanical axis location relative to the deformed limb, distance of the deformity from the joint, and determination of the intra-articular effect on bone cuts and implant position absent osteotomy. In the course of pre-operative planning, osteotomy is suggested when there is inability to correct the mechanical axis to neutral without excessive bone cuts which compromise ligament or patellar tendon attachment sites, or alternatively when adequate adjustment of cuts will likely lead to excessive
The aim of this study was to evaluate whether achieving medial joint opening, as measured by the change in the joint line convergence angle (∆JLCA), is a better predictor of clinical outcomes after high tibial osteotomy (HTO) compared with the mechanical axis deviation, and to find individualized targets for the redistribution of load that reflect bony alignment, joint laxity, and surgical technique. This retrospective study analyzed 121 knees in 101 patients. Patient-reported outcome measures (PROMs) were collected preoperatively and one year postoperatively, and were analyzed according to the surgical technique (opening or closing wedge), postoperative mechanical axis deviation (deviations above and below 10% from the target), and achievement of medial joint opening (∆JLCA > 1°). Radiological parameters, including JLCA, mechanical axis deviation, and the difference in JLCA between preoperative standing and supine radiographs (JLCAPD), an indicator of medial soft-tissue laxity, were measured. Cut-off points for parameters related to achieving medial joint opening were calculated from receiver operating characteristic (ROC) curves.Aims
Methods
Sagittal plane imbalance (SPI), or asymmetry between extension and flexion gaps, is an important issue in total knee arthroplasty (TKA). The purpose of this study was to compare SPI between kinematic alignment (KA), mechanical alignment (MA), and functional alignment (FA) strategies. In 137 robotic-assisted TKAs, extension and flexion stressed gap laxities and bone resections were measured. The primary outcome was the proportion and magnitude of medial and lateral SPI (gap differential > 2.0 mm) for KA, MA, and FA. Secondary outcomes were the proportion of knees with severe (> 4.0 mm) SPI, and resection thicknesses for each technique, with KA as reference.Aims
Methods
The kinematic alignment (KA) approach to total knee arthroplasty (TKA) has recently increased in popularity. Accordingly, a number of derivatives have arisen and have caused confusion. Clarification is therefore needed for a better understanding of KA-TKA. Calipered (or true, pure) KA is performed by cutting the bone parallel to the articular surface, compensating for cartilage wear. In soft-tissue respecting KA
Orthopaedic surgeons are currently faced with an overwhelming number of choices surrounding total knee arthroplasty (TKA), not only with the latest technologies and prostheses, but also fundamental decisions on alignment philosophies. From ‘mechanical’ to ‘adjusted mechanical’ to ‘restricted kinematic’ to ‘unrestricted kinematic’ — and how constitutional alignment relates to these — there is potential for ambiguity when thinking about and discussing such concepts. This annotation summarizes the various alignment strategies currently employed in TKA. It provides a clear framework and consistent language that will assist surgeons to compare confidently and contrast the concepts, while also discussing the latest opinions about alignment in TKA. Finally, it provides suggestions for applying consistent nomenclature to future research, especially as we explore the implications of 3D alignment patterns on patient outcomes. Cite this article:
No predictive model has been published to forecast operating time for total knee arthroplasty (TKA). The aims of this study were to design and validate a predictive model to estimate operating time for robotic-assisted TKA based on demographic data, and evaluate the added predictive power of CT scan-based predictors and their impact on the accuracy of the predictive model. A retrospective study was conducted on 1,061 TKAs performed from January 2016 to December 2019 with an image-based robotic-assisted system. Demographic data included age, sex, height, and weight. The femoral and tibial mechanical axis and the osteophyte volume were calculated from CT scans. These inputs were used to develop a predictive model aimed to predict operating time based on demographic data only, and demographic and 3D patient anatomy data.Aims
Methods
Nearly 99,000 total knee arthroplasties (TKAs) are performed in UK annually. Despite plenty of research, the satisfaction rate of this surgery is around 80%. One of the important intraoperative factors affecting the outcome is alignment. The relationship between joint obliquity and functional outcomes is not well understood. Therefore, a study is required to investigate and compare the effects of two types of alignment (mechanical and kinematic) on functional outcomes and range of motion. The aim of the study is to compare navigated kinematically aligned TKAs (KA TKAs) with navigated mechanically aligned TKA (MA TKA) in terms of function and ROM. We aim to recruit a total of 96 patients in the trial. The patients will be recruited from clinics of various consultants working in the trust after screening them for eligibility criteria and obtaining their informed consent to participate in this study. Randomization will be done prior to surgery by a software. The primary outcome measure will be the Knee injury and Osteoarthritis Outcome Score The secondary outcome measures include Oxford Knee Score, ROM, EuroQol five-dimension questionnaire, EuroQol visual analogue scale, 12-Item Short-Form Health Survey (SF-12), and Forgotten Joint Score. The scores will be calculated preoperatively and then at six weeks, six months, and one year after surgery. The scores will undergo a statistical analysis.Aims
Methods
Bi-unicondylar arthroplasty (Bi-UKA) is a bone and anterior cruciate ligament (ACL)-preserving alternative to total knee arthroplasty (TKA) when the patellofemoral joint is preserved. The aim of this study is to investigate the clinical outcomes and biomechanics of Bi-UKA. Bi-UKA subjects (n = 22) were measured on an instrumented treadmill, using standard gait metrics, at top walking speeds. Age-, sex-, and BMI-matched healthy (n = 24) and primary TKA (n = 22) subjects formed control groups. TKA subjects with preoperative patellofemoral or tricompartmental arthritis or ACL dysfunction were excluded. The Oxford Knee Score (OKS) and EuroQol five-dimension questionnaire (EQ-5D) were compared. Bi-UKA, then TKA, were performed on eight fresh frozen cadaveric knees, to investigate knee extensor efficiency under controlled laboratory conditions, using a repeated measures study design.Aims
Methods
Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology. This prospective study included 30 consecutive patients undergoing robotic-assisted TKA using the Stryker PS Triathlon implant with functional alignment. Intraoperative soft-tissue balance was assessed using sensor-guided technology after definitive component implantation; soft-tissue balance was defined as intercompartmental pressure difference (ICPD) of < 15 psi. Medial and lateral compartment pressures were recorded at 10°, 45°, and 90° of knee flexion. This study included 18 females (60%) and 12 males (40%) with a mean age of 65.2 years (SD 9.3). Mean preoperative hip-knee-ankle deformity was 6.3° varus (SD 2.7°).Aims
Methods
Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.
An algorithm to determine the constitutional alignment of the lower limb once arthritic deformity has occurred would be of value when undertaking kinematically aligned total knee arthroplasty (TKA). The purpose of this study was to determine if the arithmetic hip-knee-ankle angle (aHKA) algorithm could estimate the constitutional alignment of the lower limb following development of significant arthritis. A matched-pairs radiological study was undertaken comparing the aHKA of an osteoarthritic knee (aHKA-OA) with the mechanical HKA of the contralateral normal knee (mHKA-N). Patients with Grade 3 or 4 Kellgren-Lawrence tibiofemoral osteoarthritis in an arthritic knee undergoing TKA and Grade 0 or 1 osteoarthritis in the contralateral normal knee were included. The aHKA algorithm subtracts the lateral distal femoral angle (LDFA) from the medial proximal tibial angle (MPTA) measured on standing long leg radiographs. The primary outcome was the mean of the paired differences in the aHKA-OA and mHKA-N. Secondary outcomes included comparison of sex-based differences and capacity of the aHKA to determine the constitutional alignment based on degree of deformity.Aims
Methods
The purpose of this study was to develop an accurate, reliable and easily applicable method for determining the anatomical location of the joint line during revision knee arthroplasty. The transepicondylar width (TEW), the perpendicular distance between the medial and lateral epicondyles and the distal articular surfaces (DMAD, DLAD) and the distance between the medial and lateral epicondyles and the posterior articular surfaces (PMAD, DLAD) were measured in 40 knees from 20 formalin-fixed adult cadavers (11 male and nine female; mean age at death 56.9 years, Objectives
Methods
Many aspects of total knee arthroplasty have
changed since its inception. Modern prosthetic design, better fixation techniques,
improved polyethylene wear characteristics and rehabilitation, have
all contributed to a large change in revision rates. Arthroplasty
patients now expect longevity of their prostheses and demand functional
improvement to match. This has led to a re-examination of the long-held
belief that mechanical alignment is instrumental to a successful
outcome and a focus on restoring healthy joint kinematics. A combination
of kinematic restoration and uncemented, adaptable fixation may
hold the key to future advances. Cite this article:
Mechanical alignment has been a fundamental tenet of total knee arthroplasty (TKA) since modern knee replacement surgery was developed in the 1970s. The objective of mechanical alignment was to infer the greatest biomechanical advantage to the implant to prevent early loosening and failure. Over the last 40 years a great deal of innovation in TKA technology has been focusing on how to more accurately achieve mechanical alignment. Recently the concept of mechanical alignment has been challenged, and other alignment philosophies are being explored with the intention of trying to improve patient outcomes following TKA. This article examines the evolution of the mechanical alignment concept and whether there are any viable alternatives.
The lateral compartment is predominantly affected
in approximately 10% of patients with osteoarthritis of the knee. The
anatomy, kinematics and loading during movement differ considerably
between medial and lateral compartments of the knee. This in the
main explains the relative protection of the lateral compartment
compared with the medial compartment in the development of osteoarthritis.
The aetiology of lateral compartment osteoarthritis can be idiopathic,
usually affecting the femur, or secondary to trauma commonly affecting
the tibia. Surgical management of lateral compartment osteoarthritis
can include osteotomy, unicompartmental knee replacement and total
knee replacement. This review discusses the biomechanics, pathogenesis
and development of lateral compartment osteoarthritis and its management. Cite this article:
Biomechanical studies involving all-wire and hybrid types of circular frame have shown that oblique tibial fractures remain unstable when they are loaded. We have assessed a range of techniques for enhancing the fixation of these fractures. Eight models were constructed using Sawbones tibiae and standard Sheffield ring fixators, to which six additional fixation techniques were applied sequentially. The major component of displacement was shear along the obliquity of the fracture. This was the most sensitive to any change in the method of fixation. All additional fixation systems were found to reduce shear movement significantly, the most effective being push-pull wires and arched wires with a three-hole bend. Less effective systems included an additional half pin and arched wires with a shallower arc. Angled pins were more effective at reducing shear than transverse pins. The choice of additional fixation should be made after consideration of both the amount of stability required and the practicalities of applying the method to a particular fracture.