Success Of Total Knee Arthroplasty Research Articles

Estimating aspect ratio of the distal femur and proximal tibia in the Emirati population from MRI scans of the knee: a preliminary experience

Size and shape of knee implants play an important role in the success of total knee arthroplasty. Several studies have identified anthropometric differences of the distal femur and proximal tibia between the genders and ethnicities. Ill-fitting prosthesis can cause overhang or under-fit resulting in persistence of pain, periprosthetic fracture and decreased range of motion. The purpose of this study was to estimate the aspect ratio of distal femur and proximal tibia in the Emirati population and determine whether gender differences exist within this group. Magnetic resonance imaging datasets of unilateral knees scans performed on adult Emirati patients at a tertiary care hospital were retrospectively examined. Knee parameters were obtained from 65 males and 46 females (n = 111). Females showed significantly smaller AP and ML dimensions of distal femur and lower aspect ratios compared to males (p < 0.001). Proximal tibial dimensions (AP and ML) of Emirati women are also significantly smaller compared to men. However, aspect ratio of proximal tibia did not show gender variation (p = 0.956) within the Emirati population. Emirati knees showed significant gender differences in bony dimensions and aspect ratio of the knee, and also have smaller aspect ratios when compared with most other population groups.

Patellar tendon elastic properties derived from in vivo loading and kinematics

Patellar complications frequently limit the success of total knee arthroplasty. In addition to the musculoskeletal forces themselves, patellar tendon elastic properties are essential for driving patellar loading. Elastic properties reported in the literature exhibit high variability and appear to differ according to the methodologies used. Specifically in total knee arthroplasty patients, only limited knowledge exists on in vivo elastic properties and their corresponding loads. For the first time, we report stiffness, Young’s modulus, and forces of the patellar tendon, derived from four patients with telemetric total knee arthroplasties using a combined imaging and measurement approach. To achieve this, synchronous in vivo telemetric assessment of tibio-femoral contact forces and fluoroscopic assessment of knee kinematics, along with full body motion capture and ground reaction forces, fed musculoskeletal multi-body models to quantify patellar tendon loading and elongation. Mechanical patellar tendon properties were calculated during a squat and a sit-stand-sit activity, with resulting tendon stiffness and Young’s modulus ranging from 511 to 1166 N/mm and 259 to 504 MPa, respectively. During these activities, the patellar tendon force reached peak values between 1.31 and 2.79 bodyweight, reaching levels of just ∼0.5 bodyweight below the tibio-femoral forces. The results of this study provide valuable input data for mechanical simulations of the patellar tendon and the whole resurfaced knee.

Not All Patients Need Supervised Physical Therapy After Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Although postoperative physical therapy (PT) has long been considered essential to successful total knee arthroplasty (TKA) recovery, recent literature has suggested that unsupervised home exercise regimens may offer similar benefits to formal supervised sessions. We aimed to compare objectively measured physical function and subjective patient-reported outcomes (PROs) between primary TKA patients who received formal supervised physical therapy sessions and those who received unsupervised home exercise regimens after discharge. Six electronic databases were queried to identify randomized controlled trials comparing supervised physical therapy to unsupervised home exercise regimens in primary TKA patients after discharge. Outcomes of interest included change from baseline in objective measures (knee flexion range of motion (ROM), lower extremity strength, and aerobic capacity) and PROs (physical function and quality of life scores). These outcomes were subdivided into short-term (<6 months from surgery; closest data point to three months is used if multiple measurements were made in this time period) and long-term (≥6 months from surgery; closest data point to 12 months is used if multiple measurements were made in this time period) assessments. A total of 1,884 cases performed in 11 studies were included in this review. There were no significant differences between cohorts with regardto short-term knee flexion ROM (p = 0.7), lower extremity strength (p = 0.6), or patient-reported quality of life (p = 0.5), as well as long-term knee flexion ROM (p = 0.7), patient-reported quality of life (p = 0.2), or patient-reported physical outcome scores (p = 0.3). A small difference in short-term patient-reported physical outcomes was observed in favor of the supervised cohort (standardized mean difference(SMD): 0.3 (95% confidence interval (CI): 0.01, 0.6); I2= 82%; p = 0.04). Formal supervised physical therapy regimens do not confer clinically significant benefits over unsupervised home exercise regimens following primary TKA. The routine use of supervised physical therapy after discharge may not be warranted. Further study is needed to determine the subset of patients that may benefit from supervised care.

Fulfilment of patients’ mandatory expectations are crucial for satisfaction: a study amongst 352 patients after total knee arthroplasty (TKA)

PurposePatient satisfaction with the results of their total knee arthroplasty (TKA) is one of the primary goals of this elective procedure. Furthermore, the association between the fulfilment of patients’ expectations and their satisfaction is well known. The aim of this study was to identify the key expectations of patients awaiting a TKA, evaluate their fulfilment, and compare the outcomes between very and not fully satisfied patients.MethodsA prospective cohort study of patients with knee OA scheduled for primary TKA was performed. Pre- and one-year postoperatively patient-reported outcome measures (PROMs) were assessed. Expectations and their fulfilment were evaluated via a questionnaire encompassing 31 expectations. Preoperatively, expectations were indicated as mandatory, desirable and not important. Postoperatively, fulfilment was rated as exceeded, fulfilled, partially or not fulfilled, and not applicable. Satisfaction with the results of TKA was measured with a numeric rating scale (NRS) of 0–10. Discrimination between not fully satisfied and very satisfied patients was set at ≥ 8, as has been proposed recently. To identify independent predictors of this discrimination, a multivariate logistic regression analysis was performed.ResultsComplete data sets of 352 patients were analysed. A set of 17 key expectations was identified. Relief of knee pain was fulfilled the most, and improvement of physical function was fulfilled the least. When asked about overall fulfilled expectations, 40% of patients rated them as exceeded, 34% as fulfilled and 26% as less fulfilled than expected. Not fully satisfied patients showed significantly lower PROMs pre- and postoperatively and less fulfilled key expectations. Higher numbers of exceeded and fulfilled mandatory expectations, higher overall fulfilment and better range of motion (ROM) were significant predictors for satisfaction ≥ 8.ConclusionPatients’ expectations of TKA outcomes were high with equal emphasis on knee-related and general health-related aspects. Their fulfilment was positively associated with satisfaction. Surgeons should ask patients about mandatory expectations for successful TKA and counsel them about the likelihood of their fulfilment to avoid unrealistic expectations.Level of evidenceII.

Reappraisal of the proximal tibia anatomy in Turkish population.

Total knee arthroplasty has been popular in recent years. Morphometry of proximal tibia is important for surgeons to perform successful total knee arthroplasty. Aim of this study was to reappraise the proximal tibia morphometry. In this study, 57 human dry tibia were evaluated. Anteroposterior and mediolateral dimensions of tibial condyles, maximum width of superior articular surface and length of tibia were measured. Furthermore, morphometric measurements of the intercondylar area and Gerdy's tubercle (infracondylar tibial tubercle) were done. All measurements were performed by two observers using a digital caliper. Mean anteroposterior and mediolateral dimensions of medial tibial condyle were found 39.76 and 23.27mm, respectively. Mean anteroposterior and mediolateral dimensions of lateral tibial condyle were measured 34.72 and 21.83mm, respectively. Mean anteroposterior dimension of intercondylar area was 41.62mm. Shape of the Gerdy's tubercle was oval in 76.8%, irregular in 12.5%, and triangular in 10.7%. Texture of the tubercle was smooth in 85.7% and rough in 14.3%. Mean superoinferior and mediolateral dimensions of Gerdy's tubercle were 12.28 and 10.27mm, respectively. Anteroposterior and mediolateral dimensions of tibial condyles were significantly higher (p < 0.05) for the medial condyle. Positive and statistically significant correlations were found between the tibial length and the other parameters (p < 0.05, r > 0.40). The morphometric data of tibial plateau are important for surgeons during total knee arthroplasty. The superoinferior and mediolateral dimensions of the Gerdy's tubercle, the distance between Gerdy's tubercle and tibial tuberosity, the distance between Gerdy's tubercle and lateral tibial plateau were measured for the first time in our study. The data obtained from this study can be used as a guideline in designing tibial component of the total knee prosthesis in Turkish population. In arthroplasty, patient-specific prosthetic implants may eradicate implant mismatch in the near future.

Big stride in gene therapy for hemophilia B in China.

Big stride in gene therapy for hemophilia B in China.

Native knee kinematics is not reproduced after sensor guided cruciates substituting total knee arthroplasty

PurposeGait analysis was used to evaluate knee kinematics in patients who underwent successful primary total knee arthroplasty (TKA) using two modern bi-cruciate substituting designs. The knee joint was balanced intraoperatively using real-time sensor technology, developed to provide dynamic feedback regarding stability and tibiofemoral load. The authors hypothesized that major differences exist in gait parameters between healthy controls and post-TKA patients.MethodsTen patients who underwent successful TKA using bi-cruciate substituting designs were evaluated at a minimum of 9 months postoperatively using three-dimensional knee kinematic analysis; a multi-camera optoelectronic system and a force platform were used. Sensor-extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA) and knee rotational angle at heel-strike. Multiple gait analysis data from the study group were compared to a group of ten healthy controls who were matched by age, sex and BMI. Clinical outcome in the TKA group was also measured using the Knee injury and Osteoarthritis Outcome Score (KOOS).ResultsClinically, at final follow-up, a statistically significant difference in pain, general symptoms, and activities of daily living was seen between the groups. From a gait analysis standpoint, TKA patients had significantly less rotation at heel strike (p = 0.04), lower late stance peak extension moments (p = 0.02), and less Knee Adduction Angle excursion during swing phase (p = 0.04) compared to the control group. No statistically significant difference was observed for knee flexion angle at heel strike, knee adduction moment, or peak knee flexion moment between the groups.ConclusionsModern bi-cruciate substituting TKA designs failed to reproduce normal knee kinematics. The lack of full knee extension during the stance phase, absence of the “screw-home mechanism” typical of an ACL functioning knee, and the reduced fluctuation in knee adduction angle during the swing phase still represent major proprioceptive and muscular recruitment differences between normal and replaced knees.

The Effect of Systolic Blood Pressure on Cement Penetration Depth in Primary Total Knee Arthroplasty

Background: Cement Penetration Depth (CPD) into bone is an important factor for successful Total Knee Arthroplasties (TKA). Our study investigated the effect of Systolic Blood Pressure (SBP) on average tibial, femoral and total CPD in primary TKA. Methods and Findings: In this retrospective cohort study, patients who had a primary TKA between November 2018 and February 2020 at four, academic medical centers were included. CPD was evaluated according to the Knee Society Radiographic Evaluation System on radiographs one month post-operatively. Two independent evaluators measured four zones of tibial penetration and three zones of femoral penetration and averaged their results. The measurements were combined to create an average tibial, average femoral and average total CPD. SBP was collected at the 3/4 time of surgery length- the estimated time of cementation. 1221 primary TKA cases were included in the study – 1128 in the tourniquet group and 93 in the tourniquet-less group. There were no significant differences between the age, sex, BMI, or LOS between the two cohorts. A multiple, multivariate analysis was performed. In the tourniquet-less group, SBP did not significantly affect average tibial CPD (p=0.98), average femoral CPD (p=0.45), or average total CPD (p=0.23). However, tourniquet use was found to significantly increase average femoral (p&lt;0.001) and total penetration (p=0.001). Conclusion: SBP did not significantly affect tibial, femoral, or total CPD in patients undergoing tourniquet-less, primary TKA. However, the use of a tourniquet significantly aids in average femoral and total CPD. The clinical significance of this difference needs further investigation.

A study on topography of tibial plateau and its applications in knee arthroplasty

Introduction and Aim: This investigation was designed for evaluating the tibial plateau in Indian population and compares the data with other populations. The major intention is to observe if significant difference exists in diverse a demographic profile that necessitates production of population specific implants ensuring success in total knee arthroplasty. Materials and Methods: Morphometry of 200 adult human tibial plateaus were measured in dry bones using a sliding digital caliper and data analysis was done. Results: The mean anteroposterior dimension of the medial condyle was 38.98 ± 4.46 mm on the left and 38.81 ± 5.05 mm on the right and the lateral condyle was 32.99 ± 4.01mm on the left and 32.42 ± 4.88 mm on the right. The mean transverse dimension of the medial condyle was 24.95 ± 3.22 mm on the left and 24.54 ± 2.69 mm on the right and the lateral condyle was 28.15 ± 4.10 mm on the left and 27.76 ± 3.50 mm on the right. The anteroposterior dimension of the intercondylar area was 44.78 ± 3.87 mm on the left and 44.19 ± 4.51mm on the right. Conclusion: The data obtained will help in designing tibial prosthetic implants best suited for Indian population. The surgeon can assess how much a given deformity deviates from the normal values. The dimensions of the tibial plateau vary in different populations and most available prosthesis is designed based on Caucasian data. The tibial prosthetic sizing needs to be population specific to avoid a mismatch or mediolateral overhang.

Fixed 6° distal femoral cut consistently achieves neutral alignment for Asians, Caucasians, and Native Hawaiian/Pacific Islanders.

Restoration of a neutral mechanical axis (MA) is important to the success of total knee arthroplasty (TKA). While known differences are present between Asians and Caucasians regarding native knee alignment, it is unknown whether such differences exist amongst Native Hawaiian/Other Pacific Islanders (NHPI) or if utilizing a fixed distal femoral cut of 6° can consistently achieve a neutral MA in these minority racial groups. This study examines the preoperative deformities presented by Asians, Caucasians, and NHPI, and the resulting knee alignment achieved following TKA when a fixed 6° distal femoral cut is targeted for all patients. Preoperative and postoperative MA was measured from 835 Asian, 447 Caucasian, and 163 NHPI hip-to-ankle radiographs. All patients underwent TKA in which a standard distal femoral cut of 6° valgus was targeted for all patients. Data were evaluated as continuous variables and by groupings of varus (MA < - 3°), valgus (MA > 3°), and neutral (- 3° ≤ MA ≤ 3°) alignment. Preoperative deformity ranged from 38° varus to 29° valgus. The proportion of Asian and NHPI presenting with varus alignment prior to surgery was significantly greater than Caucasian patients in both males (Asians: 80.6%; Caucasians: 67.0%; NHPI: 79.0%, p = 0.001) and females (Asians: 66.1%; Caucasians: 45.7%; NHPI: 63.2%, p < 0.001). There was no difference in the proportion of patients (72-79%) achieving a neutral MA amongst all three racial groups. NHPI appear to have similar preoperative deformities to Asians with both groups having significantly more varus alignment than Caucasians. Despite a wide range of preoperative deformity, application of a fixed distal femoral cut of 6° valgus successfully established a neutral MA equally in the majority of patients across all three racial groups.

Prospective sequential comparison of femoral roll-back between cruciate-retaining and posterior-stabilized total knee arthroplasty using an intra-operative sensor

BackgroundImplant design and surgical techniques affect postoperative knee kinematics in total knee arthroplasty (TKA). This study aimed to compare femoral roll-back between cruciate-retaining (CR) and posterior-stabilized (PS) TKA in the same knee by objectively quantifying the contact point kinematics of the tibiofemoral joint using a sensor. MethodsIn the present prospective study, we used an intraoperative sensor to compare medial and lateral roll-back during 0-120° knee flexion in 33 knees that underwent CR and PS TKA. We also examined the relationship between mediolateral balance and the lateral-to-medial roll-back ratio. We defined the contact percentage position as the vertical length to the contact point divided by the anteroposterior length of the tibial plate. ResultsThe roll-back percentage following PS TKA (19.8 ± 5.1%) was significantly higher than that after CR TKA in both the medial (19.8 ± 5.1% versus 7.1 ± 2.5%, P < 0.001) and lateral (26.8% ± 3.8% versus 18.7 ± 3.8%, P < 0.001) compartments. The medial contact pressure at 90° was significantly correlated with the increased lateral-to-medial roll-back ratio in both CR and PS TKA (both P < 0.001). ConclusionPS TKA resulted in a higher percentage of femoral roll-back in the medial and lateral compartments than CR TKA. CR TKA caused a higher lateral-to-medial roll-back ratio compared to PS TKA. To reproduce medial pivot knee motion similar to that of a normal knee, the medial soft tissue needed to be balanced more tightly than the lateral soft tissue during TKA. These findings provide some clinical evidence of TKA design selection and proper mediolateral balancing for successful TKA.

Mechanical Alignment in Total Knee Arthroplasty for Varus Knee Osteoarthritis Leads to Significant Tibial Bone Loss.

Background Obtaining a neutral postoperative alignment is said to be a guiding principle for performing a successful total knee arthroplasty (TKA). There are many different alignment philosophies and surgical techniques to attain the goal of proper alignment. This study aimed to radiologically measure the difference in the amount of tibial bony resection required to perform a mechanical alignment versus an anatomic alignment TKA. Methods Two observers retrospectively reviewed the long leg radiographs of 100 patients (61 females and 39 males) listed for TKA between 2015 and 2018, measuring the amount of tibial bony resection required to achieve mechanical or anatomic alignment TKA. Results These radiographs' overall lower limb mechanical axis ranged between 16° varus and 17.6° valgus (mean 4.4° varus, standard deviation (SD) 6.64). By referencing 4 mm from the worn side, the mean resection needed from the normal side of the tibial plateau is 7.6 mm in the mechanical alignment measurement and 5.2 mm in the anatomical alignment measurement (p<0.0001). Therefore, 17% of mechanical alignment cuts require a tibial cut of more than 10 mm (mean 12.382 mm). No anatomical alignment measurements exceed 10 mm. When a virtual tibial cut >10 mm is required, the medial proximal tibial angle (MPTA) is a stronger predictor of deformity than the mechanical axis. Conclusion This radiological study shows that an anatomical alignment tibial cut is more bone conserving on the tibia than a mechanical alignment tibial cut and may lead to less asymmetry of the bony cuts and greater bony preservation, but clinical correlation is needed.

Modified Whiteside’s Line-Based Transepicondylar Axis for Imageless Total Knee Arthroplasty

One of the aims of successful total knee arthroplasty (TKA) is to restore the natural range of motion of the infected joint. The operated leg motion highly depends on the coordinate systems that have been used to prepare the bone surfaces for an implant. Assigning a perfect coordinate system to the knee joint is a considerable challenge. Various commercially available knee arthroplasty devices use different methods to assign the coordinate system at the distal femur. Transepicondylar axis (TEA) and Whiteside’s line are commonly used anatomical axes for defining a femoral coordinate system (FCS). However, choosing a perfect TEA for FCS is trickier, even for experienced surgeons, and a small error in marking Whiteside’s line leads to a misaligned knee joint. This work proposes a modified Whiteside’s line method for the selection of TEA. The Whiteside’s line, along with the knee center and femur head center, define two independent central planes. Multiple prominent points on the lateral and medial sides of epicondyles are marked. Based on the lengths of perpendicular distances between the multiple points and central planes, the most prominent epicondyle points are chosen to define an optimal TEA. Compared to conventional techniques, the modified Whiteside’s line defines a repeatable TEA

Intraoperative midflexion medial laxity using navigation affects patient expectations following posterior stabilized total knee arthroplasty.

Patient satisfaction and expectations are now recognized as an outcome measure for successful total knee arthroplasty (TKA). The purpose of this study was to determine which factors including soft tissue balance during surgery affect patient satisfaction and expectations after TKA. A total of 135 patients (157 knees) with knee osteoarthritis who underwent primary TKA with a posterior stabilized design were studied. After implantation of all components, varus/valgus laxity of the knee was measured intraoperatively with the knee at 0°, 30°, 60°, 90°, and 120° guided by an image-free navigation system. Factors that affected patient satisfaction and expectations, including lateral and medial laxities, were evaluated using the 2011 Knee Society score. The mean intraoperative lateral laxity was 1.1°, 1.6°, 0.9°, 1.3°, and 1.7° with the knee at 0°, 30°, 60°, 90°, and 120°, respectively. The mean intraoperative medial laxity was 1.1°, 1.4°, 1.1°, 1.1°, and 1.7° with the knee at 0°, 30°, 60°, 90°, and 120°, respectively. Patient satisfaction after TKA correlated positively with symptom (R = 0.61, p < 0.01) and functional activity (R = 0.47, p < 0.01) scores. Patient expectations after TKA weakly positively correlated with symptom (R = 0.29, p < 0.01) and functional activity (R = 0.20, p = 0.01) scores, and weakly negatively with medial laxity at 30° (R = -0.21, p < 0.01). Midflexion medial laxity was associated with worse patient expectations after TKA. Avoiding medial laxity could be one of the important techniques during TKA.

Sagittal Patellar Offset Ratio Can Be a Predictor of Anterior Knee Pain after Primary Total Knee Arthroplasty without Patella Resurfacing.

Anterior knee pain (AKP) is an issue that persists even after successful total knee arthroplasty (TKA). In some patients, reasons for AKP occurrence are known, but it is unexplained in some others despite the patellofemoral joint being thought to be the main focus of pain. We investigated the relationship between unexplained AKP and the patellofemoral joint in the sagittal plane after primary TKA. We evaluated 372 knees of 317 patients retrospectively, who had completed a minimum 24-month follow-up. We divided them into two groups according to the presence of AKP. Sagittal patellar offset ratio (SPOR), anterior femoral offset ratio (AFOR), and Insall-Salvati ratio (ISR) were measured on lateral X-rays. Clinical outcomes were evaluated using the Oxford knee score (OKS) and WOMAC pre-and postoperatively, and AKP was evaluated using a visual analog scale (VAS) postoperatively. Between non-AKP and AKP groups, SPOR (p<0.001) and AFOR (p=0.03) were significantly different but not ISR (p=0.89). SPOR and AFOR were found to be two independent risk factors that may predict the likelihood of AKP. Receiver operating characteristic (ROC) analysis revealed that AFOR is a poor value, whereas SPOR is a reasonable predictive value. No correlation between SPOR and postoperative OKS (p=0.92) and WOMAC (p=0.25) and no correlation between AFOR and postoperative OKS (p=0.44) and WOMAC (p=0.58) were found. We found that SPOR is a good predictive tool with a cutoff value of 46.4% and 91.5% sensitivity for AKP and its increased ratio increases the probability of AKP following TKA. Considering that the patellar offset will not change, especially in patients without patella resurfacing, care should be taken not to increase the anterior femoral offset.

Knee osteoarthrosis with extra-articular femoral deformity treated with total knee arthroplasty: A case series

A successful Total knee arthroplasty (TKA) procedure requires restoration of mechanical axis and soft tissue balancing. Deformity of tibia and femur occurs with history of trauma or osteotomy, infection, metabolic bone disease and excessive bowing. Tackling pre-existing extra-articular deformity of lower limbs during total knee arthroplasty can be challenging due to difficulty in restoring alignment axis and soft tissue balancing. We have recorded 6 patients underwent total knee arthroplasty with preexisting extra-articular femoral deformity by intra-articular correction from 1995 to 2017. All patients had extra-articular deformity of the femur due to fracture malunion which were treated either conservatively, plating or intra-medullary nail. Coronal deformity is corrected from an average of 15.5 degrees to 4.6 degrees from neutral axis. Sagittal deformity is corrected from average of 6.8 degrees to 3.6 degrees. One patient developed progressive genu recurvatum at 7 years follow-up with range of motion at 25 degrees extension and 110 degrees flexion. The average pre-operative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was 68.5 (range 51−87) decreased to 50.7 (range 21–71) at 12 months post-operative and Knee score averaged 53.3 (range 51–55) increased to an average of 88.5 (range 82–94). There was only one revision for aseptic loosening 16 years after total knee replacement (TKR) and no other cases of radiological sign of aseptic loosening. In conclusion, Intra-articular correction of an extra articular femoral deformity for TKR is an attractive approach in mild to moderate deformity further from the knee joint.

The associations of implant and patient factors with migration of the tibial component differ by sex

Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA. Radiostereometric analysis (RSA) data over a two-year period were available for 419 successful primary TKAs (267 cemented and 152 uncemented in 257 female and 162 male patients). Longitudinal analysis of data using marginal models was performed to examine the associations of patient factors (age, sex, BMI, smoking status) and implant factors (cemented or uncemented, the size of the implant) with maximum total point motion (MTPM) migration. Analyses were also performed on subgroups based on sex and fixation. In the overall group, only fixation was significantly associated with migration (p < 0.001). For uncemented tibial components in males, smoking was significantly associated with lower migration (p = 0.030) and BMI approached significance (p = 0.061). For females with uncemented components, smoking (p = 0.081) and age (p = 0.063) approached significance and were both associated with increased migration. The small number of self-reported smokers in this study warrants cautious interpretation and further investigation. For cemented components in females, larger sizes of tibial component were significantly associated with increased migration (p = 0.004). No factors were significant for cemented components in males. The migration of uncemented tibial components was more sensitive to patient factors than cemented implants. These differences were not consistent by sex, suggesting that it may be of value to evaluate female and male patients separately following TKA. Cite this article: Bone Joint J2022;104-B(4):444-451.

Functional Outcome Based on Mechanical Axis Alignment Following Total Knee Arthroplasty.

BackgroundTotal knee arthroplasty (TKA) is the most commonly performed and highly successful surgical intervention for end-stage osteoarthritis of the knee, and it offers patients pain relief, functional recovery, and improved quality of life. The success of knee arthroplasty depends on various factors such as precise surgical technique, alignment of the limb and components, patient selection, and compliance with rehabilitation. Mechanical alignment of the lower limb has been considered an important factor in planning and assessing the success of TKA. Optimal alignment remains a matter of controversy; hence, it is paramount to assess the alignment and functional outcomes.Aim and objectiveThis study aimed to evaluate the reliability of conventional instrumentation in imparting the intended femoral and tibial coronal alignment, as well as study the functional outcome among the neutrally aligned outliers with respect to the mechanical axis of the lower limb using standing long-leg radiographs.MethodologyThis is a prospective, hospital-based, observational study that was conducted on 60 knees in 42 patients with primary osteoarthritis of the knee joint in the department of orthopedics, Satguru Partap Singh (SPS) Hospitals, Ludhiana. Patients undergoing total knee arthroplasty who fulfilled the inclusion criteria were included in our study and evaluated using Knee Society Score and knee flexion range at periodic follow-up till six months. Preoperative and postoperative standing long-leg radiographs were done for all the patients, and their functional outcome was compared among inliers and outliers.ResultsOut of these 60 total knee arthroplasties, 18 patients were operated on both knees, and 24 patients were operated on a single knee. There were 25 female patients and 17 male patients. The mean for pre-operative mechanical axis alignment angle was 11.88° ± 5.63° with a range from -3° to 27°, which changed to 2.90° ± 1.59° with a range from 0° to 8° at six months follow-up. It was observed that 42 of the knees were in the inliers, and the remaining 18 knees were in the outliers group. On comparison among inliers and outliers, we found that the mean range of motion was 108.29° ± 4.82° for the inliers group and 106.11° ± 4.04° for the outliers group (p = 0.091), depicting non-significant statistical comparison. Mean Knee Society Score values in inliers and outliers group were 152.45 ± 5.33 and 151.61 ± 3.55, respectively (p = 0.740), showing no statistical significance.ConclusionAt six months follow-up, there is no difference in the knee range of motion and Knee Society Scores between mechanical axis inliers and outliers. Thus, we conclude that although every knee arthroplasty is intended to have neutral mechanical alignment, there is no effect of mild mechanical axis malalignment on functional outcome following total knee arthroplasty in the short term.

The Influence of Component Rotational Malalignment on Early Clinical Outcomes in Total Knee Arthroplasty.

BackgroundThe most important cause of patient dissatisfaction following total knee arthroplasty (TKA) is pain. Component rotation is an important factor in the clinical success of TKA. This study aims to determine component rotational errors in patients with mobile- and fixed-bearing polyethylene inserts after TKA and also to evaluate the effect of possible malrotations on clinical outcomes.MethodsSeventy-five knees from sixty-six patients who underwent TKA were evaluated retrospectively. The patients were divided into two groups according to whether they received a mobile-bearing polyethylene insert (group 1, n = 48) or a fixed-bearing polyethylene insert (group 2, n = 27). The Hospital for Special Surgery (HSS) score, the Western Ontario and McMaster Universities Arthritis Index (WOMAC), the Lysholm Knee Scoring Scale, and the Oxford Knee Score were used for the clinical evaluation of the patients. The rotational state of the components was evaluated by computed tomography.ResultsThe HSS, WOMAC, Lysholm, and Oxford clinical scores were not significant between the two groups (p > 0.05). The effect of femoral versus tibial component rotational deviation on clinical scores was not significant between the two groups (p > 0.05). Component rotational differences did not have a significant effect on the degree of knee flexion and extension between groups (p > 0.05). When the combined rotations of the components were compared with the clinical scores of function, no significant difference was detected between groups (p > 0.05). In addition, no significant difference between the operated sides of the patients and the combined component internal rotations was found (p > 0.05).ConclusionAlthough component rotation is an important factor in the clinical success of TKA, the current study did not find a clear association between the clinical results after TKA and the internal rotation of components. Component internal rotation alone is not an important predisposing factor for pain development after TKA. We believe that this may be attributed to the significant effects of patient expectation, which is often ignored, on clinical scores.

The lifetime risk of revision following total knee arthroplasty : a New Zealand Joint Registry study.

The success of total knee arthroplasty (TKA) is usually measured using functional outcome scores and revision-free survivorship. However, reporting the lifetime risk of revision may be more meaningful to patients when gauging risks, especially in younger patients. We aimed to assess the lifetime risk of revision for patients in different age categories at the time of undergoing primary TKA. The New Zealand Joint Registry database was used to obtain revision rates, mortality, and the indications for revision for all primary TKAs performed during an 18-year period between January 1999 and December 2016. Patients were stratified into age groups at the time of the initial TKA, and the lifetime risk of revision was calculated according to age, sex, and the American Society of Anesthesiologists (ASA) grade. The most common indications for revision were also analyzed for each age group. The overall ten-year survival rate was 95.6%. This was lowest in the youngest age group (between 46 and 50 years) and increased sequentially with increasing age. The lifetime risk of requiring revision was 22.4% in those aged between 46 and 50 years at the time of the initial surgery, and decreased linearly with increasing age to 1.15% in those aged between 90 and 95 years at the time of surgery. Higher ASA grades were associated with increased lifetime risk of revision in all age groups. The three commonest indications for revision were aseptic loosening, infection, and unexplained pain. Young males, aged between 46 and 50 years, had the highest lifetime risk of revision (25.2%). Lifetime risk of revision may be a more meaningful measure of outcome than implant survival at defined time periods when counselling patients prior to TKA. This study highlights the considerably higher lifetime risk of revision surgery for all indications, including infection, in younger male patients. Cite this article: Bone Joint J2022;104-B(2):235-241.