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Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_2 | Pages 1 - 1
1 Feb 2020
Plaskos C Wakelin E Shalhoub S Lawrence J Keggi J Koenig J Ponder C Randall A DeClaire J
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Introduction. Soft tissue releases are often required to correct deformity and achieve gap balance in total knee arthroplasty (TKA). However, the process of releasing soft tissues can be subjective and highly variable and is often perceived as an ‘art’ in TKA surgery. Releasing soft tissues also increases the risk of iatrogenic injury and may be detrimental to the mechanically sensitive afferent nerve fibers which participate in the regulation of knee joint stability. Measured resection TKA approaches typically rely on making bone cuts based off of generic alignment strategies and then releasing soft tissue afterwards to balance gaps. Conversely, gap-balancing techniques allow for pre-emptive adjustment of bone resections to achieve knee balance thereby potentially reducing the amount of ligament releases required. No study to our knowledge has compared the rates of soft tissue release in these two techniques, however. The objective of this study was, therefore, to compare the rates of soft tissue releases required to achieve a balanced knee in tibial-first gap-balancing versus femur-first measured-resection techniques in robotic assisted TKA, and to compare with release rates reported in the literature for conventional, measured resection TKA [1]. Methods. The number and type of soft tissue releases were documented and reviewed in 615 robotic-assisted gap-balancing and 76 robotic-assisted measured-resection TKAs as part of a multicenter study. In the robotic-assisted gap balancing group, a robotic tensioner was inserted into the knee after the tibial resection and the soft tissue envelope was characterized throughout flexion under computer-controlled tension (fig-1). Femoral bone resections were then planned using predictive ligament balance gap profiles throughout the range of motion (fig-2), and executed with a miniature robotic cutting-guide. Soft tissue releases were stratified as a function of the coronal deformity relative to the mechanical axis (varus knees: >1° varus; valgus knees: >1°). Rates of releases were compared between the two groups and to the literature data using the Fischer's exact test. Results. The overall rate of soft tissue release was significantly lower in the robotic gap-balancing group, with 31% of knees requiring one or more releases versus 50% (p=0.001) in the robotic measured resection group and 66% (p<0.001) for conventional measured resection (table-1) [1]. When comparing as a function of coronal deformity, the difference in release rates for robotic gap-balancing was significant when compared to the conventional TKA literature data (p<0.0001) for all deformity categories, but only for varus and valgus deformities for robotic measured resection with the numbers available (varus: 33% vs 50%, p=0.010; neutral 11% vs 50%, p=0.088, valgus 27% vs 53%, p=0.048). Discussion. Robotic-assisted tibial-first gap-balancing techniques allow surgeons to plan and adjust femoral resections to achieve a desired gap balance throughout motion, prior to making any femoral resections. Thus, gap balance can be achieved through adjustment of bone resections, which is accurate to 1mm/degree with robotics, rather than through manual releasing soft tissues which is subjective and less precise. These results demonstrated that the overall rate of soft tissue release is reduced when performing TKA with predictive gap-balancing and a robotic tensioning system. For any figures or tables, please contact authors directly


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 9 | Pages 1271 - 1276
1 Sep 2012
Luyckx T Peeters T Vandenneucker H Victor J Bellemans J

Obtaining a balanced flexion gap with correct femoral component rotation is one of the prerequisites for a successful outcome after total knee replacement (TKR). Different techniques for achieving this have been described. In this study we prospectively compared gap-balancing versus measured resection in terms of reliability and accuracy for femoral component rotation in 96 primary TKRs performed in 96 patients using the Journey system. In 48 patients (18 men and 30 women) with a mean age of 65 years (45 to 85) a tensor device was used to determine rotation. In the second group of 48 patients (14 men and 34 women) with a mean age of 64 years (41 to 86), an ‘adapted’ measured resection technique was used, taking into account the native rotational geometry of the femur as measured on a pre-operative CT scan. Both groups systematically reproduced a similar external rotation of the femoral component relative to the surgical transepicondylar axis: 2.4° . (sd. 2.5) in the gap-balancing group and 1.7° (. sd. 2.1) in the measured resection group (p = 0.134). Both gap-balancing and adapted measured resection techniques proved equally reliable and accurate in determining femoral component rotation after TKR. There was a tendency towards more external rotation in the gap-balancing group, but this difference was not statistically significant (p = 0.134). The number of outliers for our ‘adapted’ measured resection technique was much lower than reported in the literature


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XLI | Pages 5 - 5
1 Sep 2012
Fujii H Azuma Y Doi K
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The two distinct surgical techniques for total knee arthroplasty (TKA) are gap-balancing technique (GB) and measured resection technique (MR). The aim of this study was to compare coronal stability of the knee after TKA with GB or MR. A total of 80 TKA cases with at least 6 months follow up (average 34.4 months) were evaluated. The MR group comprised of 33 patients with an average age of 73.1 years, while the GB group comprised of 47 patients with an average age of 74.4 years. Zimmer NexGen LPS Flex was used for all cases. Coronal stability of the knee was examined by varus-valgus stress X-ray at full extension and in the 90 degree flexed position as reported by Kanekashu et al (CORR 2005). X-ray measurement was performed using the FUJI diagnostic imaging system FS-V673. The varus-valgus stress X-ray test at full extension showed a laxity of 4.7 + 2.1 degrees in the MR group and 3.9 + 1.9 degrees in the GB group. No significant difference was detected between the two groups. On the other hand, the varus-valgus stress X-ray in the 90 degree flexed position revealed a laxity of 8.7+4.1 degrees in the MR group and 5.3 + 2.7 degrees in the GB group (p<0.01, Student's t-test). Of the 11 knees that showed laxity of >11 degrees in the 90 degree flexed position, 10 were from the MR group and only one from the GB group (p<0.01, Fisher's exact probability test). Furthermore, the postoperative clinical score assessed by Japanese Orthopaedic Association criteria was significantly better in knees with a coronal laxity of <10 degrees in the 90 degree flexed position compared to those with >10 degrees (82.7 + 6.8 and 77.3 + 8.5 in the GB and MR groups, respectively). In conclusion, GB may contribute to improved functional performance after TKA by providing better coronal stability of the knee in the 90 degree flexed position


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_4 | Pages 39 - 39
1 Jan 2016
Suzuki K Hara N Mikami S Tomita T Iwamoto K Yamazaki T Sugamoto K Matsuno S
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Backgrounds

Most of in vivo kinematic studies of total knee arthroplasty (TKA) have reported on varus knee. TKA for the valgus knee deformity is a surgical challenge. The purposes of the current study are to analyze the in vivo kinematic motion and to compare kinematic patterns between weight-bearing (WB) and non-weight-bearing (NWB) knee flexion in posterior-stabilized (PS) fixed-bearing TKA with pre-operative valgus deformity.

Methods

A total of sixteen valgus knees in 12 cases that underwent TKA with Scorpio NRG PS knee prosthesis operated by modified gap balancing technique were evaluated. The mean preoperative femorotibial angle (FTA) was 156°±4.2°. During the surgery, distal femur and proximal tibia was cut perpendicular to the mechanical axis of each bone. After excision of the menisci and cruciate ligaments, balancer (Stryker joint dependent kinematics balancer) was inserted into the gap between both bones for evaluation of extension gap. Lateral release was performed in extension. Iliotibial bundle (ITB) was released from Gerdy tubercle then posterolateral capsule was released at the level of the proximal tibial cut surface. If still unbalanced, pie-crust ITB from inside-out was added at 1 cm above joint line until an even lateral and medial gap had been achieved. Flexion gap balance was obtained predominantly by the bone cut of the posterior femoral condyle. Good postoperative stability in extension and flexion was confirmed by stress roentgenogram and axial radiography of the distal femur. We evaluated the in vivo kinematics of the knee using fluoroscopy and femorotibial translation relative to the tibial tray using a 2-dimentional to 3-dimensional registration technique.


The Bone & Joint Journal
Vol. 103-B, Issue 6 Supple A | Pages 74 - 80
1 Jun 2021
Deckey DG Rosenow CS Verhey JT Brinkman JC Mayfield CK Clarke HD Bingham JS

Aims. Robotic-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to incorporate soft-tissue laxity data into the plan prior to bone resection should reduce variability between the planned polyethylene thickness and the final implanted polyethylene. The purpose of this study was to compare accuracy to plan for component positioning and precision, as demonstrated by deviation from plan for polyethylene insert thickness in measured-resection RA-TKA versus M-TKA. Methods. A total of 220 consecutive primary TKAs between May 2016 and November 2018, performed by a single surgeon, were reviewed. Planned coronal plane component alignment and overall limb alignment were all 0° to the mechanical axis; tibial posterior slope was 2°; and polyethylene thickness was 9 mm. For RA-TKA, individual component position was adjusted to assist gap-balancing but planned coronal plane alignment for the femoral and tibial components and overall limb alignment remained 0 ± 3°; planned tibial posterior slope was 1.5°. Mean deviations from plan for each parameter were compared between groups for positioning and size and outliers were assessed. Results. In all, 103 M-TKAs and 96 RA-TKAs were included. In RA-TKA versus M-TKA, respectively: mean femoral positioning (0.9° (SD 1.2°) vs 1.7° (SD 1.1°)), mean tibial positioning (0.3° (SD 0.9°) vs 1.3° (SD 1.0°)), mean posterior tibial slope (-0.3° (SD 1.3°) vs 1.7° (SD 1.1°)), and mean mechanical axis limb alignment (1.0° (SD 1.7°) vs 2.7° (SD 1.9°)) all deviated significantly less from the plan (all p < 0.001); significantly fewer knees required a distal femoral recut (10 (10%) vs 22 (22%), p = 0.033); and deviation from planned polyethylene thickness was significantly less (1.4 mm (SD 1.6) vs 2.7 mm (SD 2.2), p < 0.001). Conclusion. RA-TKA is significantly more accurate and precise in planning both component positioning and final polyethylene insert thickness. Future studies should investigate whether this increased accuracy and precision has an impact on clinical outcomes. The greater accuracy and reproducibility of RA-TKA may be important as precise new goals for component positioning are developed and can be further individualized to the patient. Cite this article: Bone Joint J 2021;103-B(6 Supple A):74–80


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Postoperative functional outcomes and patients’ satisfaction after total knee arthroplasty are associated with postoperative range of motion. Severe deformities require surgical correction such as soft tissue release and appropriate bone resection. The goal of surgery is to correct the contracture and bring the knee to good range of motion. Using gap-balancing technique is one of the major techniques to obtain good range of motion. Although the gaps are well balanced, the thickness of tibial insert would affect the range of motion. In this study, we analyzed the difference between intraoperative extension joint gap and the thickness of implanted insert (DJI). The objective of this study was to investigate whether DJI affected the postoperative extension of the knee. A total of 155 knees were analyzed retrospectively. Subject included 27 males and 128 females with an average of 72.7 ± 7.0 years. The mean preoperative knee flexion angle was 136.1 ± 20.0°and the mean preoperative knee extension deficit was 4.0 ± 6.1°. All the patients had a diagnosis of varus-type osteoarthritis, identical prostheses (Stryker NRG posterior-stabilized type) implanted with a modified gap-balancing technique and no postoperative complications which may have affected the range of motion. Range of motion was measured using a goniometer before surgery and 12 months after surgery. Joint gap between femoral component and proximal tibia in full extension was measured by a tensor/ balancer device which added joint gap an expansion force by 30 inch pounds intra-operatively. Although we empirically regarded the appropriate DJI was 5 mm for this prosthesis, we determined the thickness of the tibial inserts considering preoperative range of motion. Thinner inserts compared with the joint gap was implanted for knees with flexion contracture and thicker inserts was implanted for knees with hyperextension. In this study, to determine the relationship of DJI and flexion contracture, the correlation coefficient between DJI and extension deficit was calculated. The diagram of DJI and postoperative extension angle is shown in Figure 1. The correlation coefficient between DJI and postoperative extension deficit was 0.24, which showed that DJI slightly affected the postoperative extension of the knee. Flexion contracture cannot be corrected by simply adjusting DJI


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_9 | Pages 17 - 17
1 Oct 2020
Hooper J Lawson K Amanatullah D Hamad C Angibaud L Huddleston JI
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Introduction. Instability is a common reason for revision after total knee arthroplasty. A balanced flexion gap is likely to enhance stability throughout the arc of motion. This is achieved differently by the gap balancing and measured resection techniques. Given similar clinical results with the two techniques, one would expect similar rotation of the femoral component in the axial plane. We assessed posterior-stabilized femoral component axial rotation placed with computer navigation and a modified gap balancing technique. We hypothesized that there would be little variation in rotation. Methods. 90 surgeons from 8 countries used a modified gap-balancing technique and the same posterior-stabilized implant for this retrospective study. Axial rotation of the femoral component was collected from a navigation system and reported relative to the posterior condylar line. Patients were stratified by their preoperative coronal mechanical alignment (≥ 3° varus, < 3° varus to < 3° valgus, and ≥ 3° valgus). Results. 2442 consecutive patients were included in the analysis; 835 with ≥ 3° varus, 1343 with < 3° varus to < 3° valgus, and 264 with ≥ 3° valgus. Mean rotation was external 2.4. 0. +/− 3.4. 0. (range, 10. 0. internal − 21. 0. external). In 16.4% of the cohort, axial rotation was set in a position of internal rotation. In 15.6% of the cohort, axial rotation was set at > 5. 0. of external rotation. Compared to both the neutral and varus groups, valgus knees required a different mean rotation to achieve a balanced flexion gap (p < .0001). Conclusion. These data show a wide range of femoral rotation was needed to achieve a rectangular flexion gap. This suggests that choosing a pre-determined femoral implant axial rotation (measured resection) may lead to flexion gap asymmetry more frequently compared to adjusting the axial rotation intraoperatively (gap-balancing). Correlation to clinical outcome scores is needed


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_1 | Pages 61 - 61
1 Feb 2020
Kaper B
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Introduction/Aim. Mid-flexion instability is a well-documented, but often poorly understood cause of failure of TKA. NAVIO robotic-assisted TKA (RA-TKA) offers a novel, integrative approach as a planning, execution as well as an evaluation tool in TKA surgery. RA-TKA provides a hybrid planning technique of measured resection and gap balancing- generating a predictive soft-tissue balance model, prior to making cuts. Concurrently, the system uses a semi-active robot to facilitate both the execution and verification of the plan, as it pertains to both the static and dynamic anatomy. The goal of this study was to assess the ability of the NAVIO RA-TKA to plan, execute and deliver an individualized approach to the soft-tissue balance of the knee, specifically in the “mid-flexion” arc of motion. Materials and Methods. Between May and September 2018, 50 patients underwent NAVIO RA-TKA. Baseline demographics were collected, including age, gender, BMI, and range of motion. The NAVIO imageless technique was used to plan the procedure, including: surface-mapping of the static anatomy; objective assessment of the dynamic, soft-tissue anatomy; and then application of a hybrid of measured-resection and gap-balancing technique. Medial and lateral gaps as predicted by the software were recorded throughout the entire arc of motion at 15° increments. After executing the plan and placing the components, actual medial and lateral gaps were recorded throughout the arc of motion. Results. In the assessment of coronal-plane balance, the average deviation from the predicted plan between 0–90° was 0.9mm in both the medial and lateral compartments (range 0.5–1.2mm). In the mid-flexion arc (15–75°), final soft-tissue stability was within 1.0mm of the predictive plan (range 0.9–1.2mm). Discussion/Conclusions. In this study, NAVIO RA-TKA demonstrated a highly accurate and reproducible surgical technique to plan, execute and verify a balanced a soft-tissue envelope in TKA. Objective soft-tissue balancing of the TKA can now be performed, including the mid-flexion arc of motion. Further analysis can determine if these objective measurements will translate into improved patient-reported outcome scores


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_3 | Pages 6 - 6
1 Apr 2019
Nithin S
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Computer assisted total knee arthroplasty helps in accurate and reproducible implant positioning, bony alignment, and soft-tissue balancing which are important for the success of the procedure. In TKR, there are two surgical techniques one is measured resection in which bony landmarks are used to guide the bone cuts and the other is gap balancing which equal collateral ligament tension in flexion and extension is done before and as a guide to final bone cuts. Both these procedures have their own advantages and disadvantages. We retrospectively collected the data of 128 consecutive patients who underwent computer-assisted primary TKA using either a gap-balancing technique or measured resection technique. All the operations were performed by a single surgeon using computer navigation system available during a period between June 2016 to October 2016. Inclusion criteria were all patients requiring a primary TKA, male or female patients, and who have given informed consent for participation in the study. All patients requiring revision surgery of a previous implanted TKA or affected by active infection or malignancy, who presented hip ankylosis or arthrodesis, neurological deficit or bone loss or necessity of more constrained implants were excluded from the study. Two groups measured resection and gap balancing was randomly selected. At 1-year follow-up, patients were assessed by a single orthopaedic registrar blinded to the type of surgery using the Knee Society score (KSS) and functional Knee Society score (FKSS). Outcomes of the 2 groups were compared using the paired t test. All the obtained data were analysed. Statistical analysis was performed using SPSS 11.5 statistical software (SPSS Inc. Chicago). Inter-class correlation coefficient (ICC) and paired t-test were used and statistical significance was set at P = 0.05. In the measured resection group, the mean FKSS increased from 48.8769 (SD, 2.3576), to 88.5692 (SD, 2.7178) respectively. In the gap balancing group, the respective scores increased from 48.9333 (SD, 3.6577) to 89.2133(SD, 7.377). Preoperative and Postoperative increases in the respective scores were slightly better with the gap balancing technique; the respective p values were 0.8493 and 0.1045. The primary goal of TKA is restoration of mechanical axis and soft-tissue balance. Improper restoration leads to poor functional outcome and premature prosthesis loosening. Computer navigation enables precise femoral and tibial cuts and controlled soft-tissue release. Well balanced and well aligned knee is important for good results. Mechanical alignment and soft-tissue balance are interlinked and corrected by soft tissue releases and precise proximal tibial and distal femoral cuts. The 2 common techniques used are measured resection and gap balancing techniques. In our study, knee scores of the 2 groups at 1-year follow-up were compared, as most of the improvement occurs within one year, with very little subsequent improvement. Some surgeons favour gap balancing technique, as it provides more consistent soft-tissue tension in TKA


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_6 | Pages 90 - 90
1 Mar 2017
Wellman S Queen R
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Introduction. Mid-flexion stability after total knee arthroplasty (TKA) is dependent, in large part, on implant design. Design variables include retention or sacrifice of the posterior cruciate ligament, conformity of the polyethylene tibial surface, and radius of curvature of the femoral component. In this study, we attempted to isolate the impact of femoral component design by comparing a single-radius design (SR) to a J-Curve design (JC). We selected cruciate-retaining implants to eliminate the effect of a cam-and-post mechanism. Mid-flexion performance these two designs were compared using the Lower-Quarter Y-Balance Test (YBT-LQ), as well as patient reported outcomes and measures of physical performance. The YBT-LQ is a simple functional test of unilateral lower extremity strength and balance. Reach of the contralateral limb is measured in three different directions (Figures 1–3). Our hypothesis was that the SR design would provide superior mid-flexion stability, and therefore, a greater reach distance in the YBT-LQ when compared to the JC group. Methods. Patients undergoing primary, unilateral TKA were prospectively enrolled and block randomized to receive either the SR (n=30) or JC (n=30) implant. All surgeries were performed by one surgeon using a gap-balancing technique with a cruciate-retaining implant design. Patients completed outcome measures (KOOS, KSS, UCLA Activity), performed the YBT-LQ, and completed physical performance measures (walking speed, timed up-and-go, sit-to-stand) before surgery and 1 year postoperatively. A series of 2×2 repeated measures ANOVAS (Implant group x Time) were completed. Results. One year post-operatively, 40 patients (20 SR, 20 JC) were available for analysis. The groups were closely matched for age, gender, BMI, and ASA score. No significant differences existed between implant groups for the YBT-LQ or any other variable of interest. Significant improvements in both implant groups were observed for all variables of interest when comparing pre-operative to one year post-operative. Conclusions. Both groups improved significantly across time in all measures, but no differences were seen between SR and JC designs. Based on reach distances achieved, it is probable that many patients were not able to achieve mid-flexion during the YBT-LQ test. With regards to mid-flexion function after TKA, the significant limitations in strength and balance in this cohort of patients likely outweigh any subtle differences in implant design. For any figures or tables, please contact authors directly (see Info & Metrics tab above).


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 143 - 143
1 May 2016
Puah K Yeo W Tan M
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Aim. Computer-navigated total knee arthroplasty has been shown to improve the outcome in outliers with consistent results. The aim of this study is to evaluate the clinical and radiographic outcomes of computer-navigated knee arthroplasty with respect to deformity and body mass index (BMI). Materials and Methods. Data was prospectively collected for 117 consecutive patients undergoing primary computer-navigated total knee arthroplasty using Ci Brainlab system with J&J PFC PS implants by a single surgeon utilising a tibia cut first, gap-balancing technique. Pre-operative and post-operative long-leg films, weight-bearing, films were taken and the long-axis was measured by a single observer. Intra-operative computer navigation long-axis values were stored as screenshots intra-operatively after registration and after implant was cemented. BMI, range of motion (ROM), SF 36 and Oxford knee scores were recorded both before surgery and on follow-up. Minimum 2-year follow-up. Eight patients were lost to follow-up and 8 had incomplete 2 year data. Data was analysed using the Chi-squared test for categorical variables and the t-test for continuous variables. Results. Eighty-four (83.2%) female, 17 (16.8%) male patients age 65.3±6.9 years with a pre-operative BMI of 27.2±4.1 (18.6 to 40.0). Eighty-eight (87.1%) met the Singapore definition of overweight with BMI>23 kg/m2. Forty-two (41.6%) had a BMI>27.5 kg/m2 indicative of obesity in Singapore. Pre-operative radiographic axis was 9.3±10.6° varus. Thirty (29.7%) patients had a pre-operative coronal plane deformity of more than 15°. Meanoperative duration 96.0±10.7 mins. Post-operative radiographic axis was 0.05±3.0° valgus. Significant improvement was seen in knee extension, knee flexion, SF 36 and Oxford knee scores at 2 years. No significant improvement in extensor lag and straight leg-raising at 2 years. Pre-operative axis >15° was not significantly related to operative duration. BMI>23 kg/m2 was significantly related to longer operative time (88.8±10.8 vs. 97.1±10.3 min, p<0.021). BMI >27.5 kg/m2 not significantly related to operative duration, pre-operative SF36 or Oxford knee scores. Post-operative axis deviation of more than 3° not significantly related to BMI > 23 or 27.5 kg/m2, similar to post-implant navigation axis. BMI >23 kg/m2 not significantly related to 2 year SF36, Oxford knee score and range of motion at 2 years. BMI >27.5 kg/m2 not significantly related to 2 year SF36 or Oxford knee scores. Conclusion. Although restoration of coronal alignment even in deformity >15° is possible with computer navigation, post-operative extensor lag and weakness is still a problem determined by pre-operative extensor lag and weakness in straight leg raising. Computer navigation is useful when exposure and landmarks to assess alignment are difficult such as in obesity where the standard external tibia jig doesn't sit well with the thick subcutaneous layer and for determining the epicondylar axis of the femur in a deep wound. Despite the technical challenges of performing a total knee arthroplasty with obesity, BMI is not a determinant of functional scores when computer navigation is used


The Bone & Joint Journal
Vol. 105-B, Issue 12 | Pages 1279 - 1285
1 Dec 2023
Baker JF Nadar AC Jouflas AC Smith LS Sachdeva S Yakkanti MR Malkani AL

Aims

The use of cementless total knee arthroplasty (TKA) components has increased during the past decade. The initial design of cementless metal-backed patellar components had shown high failure rates due to many factors. The aim of this study was to evaluate the clinical results of a second-generation cementless, metal-backed patellar component of a modern design.

Methods

This was a retrospective review of 707 primary TKAs in 590 patients from a single institution, using a cementless, metal-backed patellar component with a mean follow-up of 6.9 years (2 to 12). A total of 409 TKAs were performed in 338 females and 298 TKAs in 252 males. The mean age of the patients was 63 years (34 to 87) and their mean BMI was 34.3 kg/m2 (18.8 to 64.5). The patients were chosen to undergo a cementless procedure based on age and preoperative radiological and intraoperative bone quality. Outcome was assessed using the Knee Society knee and function scores and range of motion (ROM), complications, and revisions.


Bone & Joint 360
Vol. 12, Issue 2 | Pages 16 - 19
1 Apr 2023

The April 2023 Knee Roundup360 looks at: Does bariatric surgery reduce complications after total knee arthroplasty?; Mid-flexion stability in total knee arthroplasties implanted with kinematic alignment: posterior-stabilized versus medial-stabilized implants; Inflammatory response in robotic-arm-assisted versus conventional jig-based total knee arthroplasty; Journey II bicruciate stabilized (JII-BCS) and GENESIS II total knee arthroplasty: the CAPAbility, blinded, randomized controlled trial; Lifetime risk of revision and patient factors; Platelet-rich plasma use for hip and knee osteoarthritis in the USA; Where have the knee revisions gone?; Tibial component rotation in total knee arthroplasty: CT-based study of 1,351 tibiae.


The Bone & Joint Journal
Vol. 106-B, Issue 6 | Pages 525 - 531
1 Jun 2024
MacDessi SJ van de Graaf VA Wood JA Griffiths-Jones W Bellemans J Chen DB

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 joint line obliquity, resulting in soft-tissue imbalance. This annotation provides an overview of how the Coronal Plane Alignment of the Knee (CPAK) classification can be used to predict imbalance with mechanical alignment, and then offers practical guidance for bone balancing, minimizing the need for soft-tissue releases.

Cite this article: Bone Joint J 2024;106-B(6):525–531.


Bone & Joint Open
Vol. 5, Issue 8 | Pages 681 - 687
19 Aug 2024
van de Graaf VA Shen TS Wood JA Chen DB MacDessi SJ

Aims

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.

Methods

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.


Bone & Joint Open
Vol. 5, Issue 11 | Pages 992 - 998
6 Nov 2024
Wignadasan W Magan A Kayani B Fontalis A Chambers A Rajput V Haddad FS

Aims

While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes.

Methods

This study included 136 patients undergoing robotic arm-assisted medial UKA between January 2018 and December 2022. The study included 75 males (55.1%) and 61 (44.9%) females, with a mean age of 67.1 years (45 to 90). Patients were divided into three study groups based on the degree of preoperative FFD: ≤ 5°, 5° to ≤ 10°, and > 10°. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. Clinical FFD was measured pre- and postoperatively at six weeks and one year following surgery. Preoperative and one-year postoperative Oxford Knee Scores (OKS) were collected.


The Bone & Joint Journal
Vol. 106-B, Issue 7 | Pages 680 - 687
1 Jul 2024
Mancino F Fontalis A Grandhi TSP Magan A Plastow R Kayani B Haddad FS

Aims

Robotic arm-assisted surgery offers accurate and reproducible guidance in component positioning and assessment of soft-tissue tensioning during knee arthroplasty, but the feasibility and early outcomes when using this technology for revision surgery remain unknown. The objective of this study was to compare the outcomes of robotic arm-assisted revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) versus primary robotic arm-assisted TKA at short-term follow-up.

Methods

This prospective study included 16 patients undergoing robotic arm-assisted revision of UKA to TKA versus 35 matched patients receiving robotic arm-assisted primary TKA. In all study patients, the following data were recorded: operating time, polyethylene liner size, change in haemoglobin concentration (g/dl), length of inpatient stay, postoperative complications, and hip-knee-ankle (HKA) alignment. All procedures were performed using the principles of functional alignment. At most recent follow-up, range of motion (ROM), Forgotten Joint Score (FJS), and Oxford Knee Score (OKS) were collected. Mean follow-up time was 21 months (6 to 36).


Bone & Joint Open
Vol. 5, Issue 9 | Pages 758 - 765
12 Sep 2024
Gardner J Roman ER Bhimani R Mashni SJ Whitaker JE Smith LS Swiergosz A Malkani AL

Aims

Patient dissatisfaction following primary total knee arthroplasty (TKA) with manual jig-based instruments has been reported to be as high as 30%. Robotic-assisted total knee arthroplasty (RA-TKA) has been increasingly used in an effort to improve patient outcomes, however there is a paucity of literature examining patient satisfaction after RA-TKA. This study aims to identify the incidence of patients who were not satisfied following RA-TKA and to determine factors associated with higher levels of dissatisfaction.

Methods

This was a retrospective review of 674 patients who underwent primary TKA between October 2016 and September 2020 with a minimum two-year follow-up. A five-point Likert satisfaction score was used to place patients into two groups: Group A were those who were very dissatisfied, dissatisfied, or neutral (Likert score 1 to 3) and Group B were those who were satisfied or very satisfied (Likert score 4 to 5). Patient demographic data, as well as preoperative and postoperative patient-reported outcome measures, were compared between groups.


Bone & Joint Open
Vol. 5, Issue 7 | Pages 592 - 600
18 Jul 2024
Faschingbauer M Hambrecht J Schwer J Martin JR Reichel H Seitz A

Aims

Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))?

Methods

Overall, 15 cadaveric knee joints were examined with a CR implant with three different tibial inserts (CR, UC, and MC) using an established knee joint simulator. The effects on coronal alignment, medial and lateral femoral roll back, femorotibial rotation, bony rotations (femur, tibia, and patella), and patellofemoral length ratios were determined.


Aims

Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity.

Methods

Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively.