Coronal alignment in total knee arthroplasty: a review

The influence of the surgeon's handedness and standing position at the operating table on the radiological outcomes in primary total knee arthroplasty

BACKGROUND

The purpose of this study was to compare radiological outcomes of total knee arthroplasty (TKA) in mechanical alignment implant positioning in the coronal and sagittal planes depending on surgeons' handedness and their position at the operating table.

METHODS

A total number of 200 consecutive patients with idiopathic osteoarthritis and varus knees who underwent TKA were retrospectively included in this research. Patients were operated on by 4 surgeons (50 for each surgeon) selected according to their handedness and position at the operative table. Surgeon I (right-handed, standing at the operating table always on the right side); Surgeon II(left-handed, standing at the operating table always on the left side); Surgeon III (right-handed, standing at the operating table on the side of the operated limb); Surgeon IV (left-handed, standing at the operating table on the side of the operated limb).

RESULTS

Comparing postoperative radiological results statistically significant differences were calculated in the case of deviation from HKA angle (left TKA -1.5°; Interquartile Range [IQR] = -2.6-[-1] vs right TKA -3°; IQR = -4.5-[-2]; p = 0.01) for surgeon II and MPTA for surgeon IV (left TKA 0°; IQR = -1-0.5 vs right TKA 1°; IQR = 0-2; p < 0.01). Higher deviation from the mechanical alignment angles and implant positioning was revealed for a less convenient operation site for the surgeon.

CONCLUSION

We recommend that all surgeons performing TKAs from the less comfortable side should take great care in establishing the MPTA and HKA angles to avoid surgical errors in implant positioning and limb alignment.

'Extended' restricted kinematic alignment results in decreased residual medial gap tightness among osteoarthritic varus knees during robotic-assisted total knee arthroplasty

Aims

The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases.

Methods

Patients who underwent RA-TKA between January and December 2022 for primary varus osteoarthritis were included. Safe boundaries for E-rKA were defined. Residual medial compartment tightness was compared following virtual surgical planning using E-rKA and MA, in the same set of knees. Soft-tissue releases were documented. Errors in postoperative alignment in relation to planned alignment were compared between patients who did (group A) and did not (group B) require soft-tissue releases.

Results

The use of E-rKA helped restore all knees within the predefined boundaries, with appropriate soft-tissue balancing. E-rKA compared with MA resulted in reduced residual medial tightness following surgical planning, in full extension (2.71 mm (SD 1.66) vs 5.16 mm (SD 3.10), respectively; p < 0.001), and 90° of flexion (2.52 mm (SD 1.63) vs 6.27 mm (SD 3.11), respectively; p < 0.001). Among the study population, 156 patients (78%) were managed with minor adjustments in component positioning alone, while 44 (22%) required additional soft-tissue releases. The mean errors in postoperative alignment were 0.53 mm and 0.26 mm among patients in group A and group B, respectively (p = 0.328).

Conclusion

E-rKA is an effective and reproducible alignment strategy during RA-TKA, permitting a large proportion of patients to be managed without soft-tissue releases. The execution of minor alterations in component positioning within predefined multiplanar boundaries is a better starting point for gap management than soft-tissue releases.

Preoperative evaluation of femoral and tibial sagittal alignment in robotic-assisted and conventional total knee arthroplasty and consequences for practice

PURPOSE

Robot-assisted total knee arthroplasty (TKA) was developed to improve the precision and accuracy of implant placement in conventional TKA. However, the angular differences between referenced axes in robot-assisted TKA and conventional TKA remain unclear. The aim of this study was to investigate the angular differences in sagittal alignment between robot-assisted TKA and conventional TKA for both the femur and the tibia and to discuss their clinical implications.

METHODS

We conducted a retrospective analysis of data from 100 patients (97 patients) who underwent computed tomography (CT) for Mako TKA. We measured the angle between the robot femoral axis (RFA) and conventional femoral axis (CFA) in the sagittal plane and the angle between the robot tibial axis (RTA) and the conventional tibial axis (CTA). Angles were compared between the sexes. Correlation analysis was conducted between the angles and height.

RESULTS

In the sagittal plane, the mean RFA-CFA angle was 2.2° ± 1.6°, and the mean RTA-CTA angle was 2.3° ± 1.6°. There were no significant differences between the two angles among males and females (p > 0.05). There was a correlation between the RFA-CFA angle and RTA-CTA angle (p < 0.001, r = 0.33), and there was a correlation between height and the combination of the RFA-CFA angle and RTA-CTA angle (p = 0.03, r = 0.22).

CONCLUSION

There are angular differences between the axes referenced by robot-assisted TKA and those referenced by conventional TKA, which may be influenced by patient height. Correctly understanding these differences is crucial when evaluating the implant position and surgical outcomes after robot-assisted TKA. Furthermore, caution should be taken when assessing the flexion-extension angle of the knee since the angles displayed in the Mako system are different from the angles measured with intramedullary anatomical axes. After all, sagittal alignment principles differ between robot-assisted and conventional TKA; however, further studies are required to determine which principle is more appropriate or to modify these principles.

Increased prevalence of valgus constitutional alignment subtypes in a South African arthritic population group using the coronal plane alignment of the knee (CPAK) classification

BACKGROUND

Knee alignment philosophies and patient specific models to improve patient reported outcomes are gaining increasing attention. The coronal plane alignment of the knee (CPAK) classification describes nine knee phenotypes and then proposes surgical alignment strategies to achieve constitutional alignment. The CPAK classification has been validated in Australian, European, Asian and North American population groups. To date no African data has been analyzed using CPAK.

METHODS

A total of 344 arthritic patients (608 knees) with appropriate long leg radiographs were classified based on the CPAK type. Measurements included mechanical hip-knee-angle(mHKA), medial proximal tibial angle (mMPTA) and lateral distal femoral angle (mLDFA) and the derived calculations of joint line obliquity (JLO) and arithmetic hip-knee-angle (aHKA).

RESULTS

The sample population was 77.9% (n = 268) female with a mean age of 68.4 ± 9.2 years. The most common CPAK types in order were type 3 (n = 174; 28.6%), type 2 (n = 155; 25.5%), type 1 (n = 94; 15.5%) and type 6 (n = 80; 13.2%). The most common limb alignment types were valgus (CPAK types 3,6,9; 41.8%).

CONCLUSION

This study, which investigated arthritic patients from a single institution in South Africa, shows a divergence of CPAK phenotypic knee patterns relative to other international studies, with much higher proportions of valgus phenotypes (3 and 6). This regional difference should be further investigated in other South African and African population samples and used to adapt the surgical strategies employed by local surgeons.

Functional knee phenotypes appear to be more suitable for the Chinese OA population compared with CPAK classification: A study based on 3D CT reconstruction models

PURPOSE

The aim of this study was to investigate the distribution of coronal plane alignment of the knee (CPAK) classification and functional knee phenotypes in a Chinese osteoarthritis (OA) population and to compare different lower limb alignment targets according to the distribution characteristics to find suitable total knee arthroplasty (TKA) bone cut strategies for the Chinese OA patients.

METHODS

The computed tomography (CT) images were retrospectively collected and the three-dimensional (3D) models were reconstructed from 434 Chinese OA patients, including 93 males and 341 females, with a mean age of 66.4 ± 9.3 years. Femoral mechanical angle (FMA), tibial mechanical angle (TMA) and mechanical hip-knee-ankle angle (mHKA) were measured on the 3D models. Arithmetic hip-knee-ankle angle (aHKA) was calculated using FMA plus TMA, and joint line obliquity was calculated as 180 + TMA-FMA. The CPAK according to MacDessi and the functional knee phenotypes according to Hirschmann were performed. In addition, the suitable TKA bone cut strategies were explored according to the phenotypes and based on the characteristics of different alignment targets, such as mechanical alignment, anatomic alignment (AA), kinematic alignment, restricted KA (rKA) and adjusted MA (aMA). Statistical differences were determined using the independent-samples t-test or the two independent-samples Wilcoxon test, with p < 0.05 considered statistically significant.

RESULTS

The Chinese OA population showed a varus alignment tendency (mHKA = 172.1° ± 7.2°), to which the TMA was a major contributor (TMA = 84.7° ± 4.4° vs. FMA = 91.3° ± 3.2°). The mHKA was on average 3.9° more varus than the aHKA. A total of 140 functional knee phenotypes were found and 45.6% were concentrated in VARFMA3°-NEUFMA0° to VARTMA3°-NEUTMA0°. More than 70% of patients had different FMA and TMA phenotypes. There were 92.9% of CPAK distributed in types I to IV, with type I accounting for 53.9%. The FMA phenotypes were less changed if the aMA and rKA were chosen, and the TMA phenotypes were less changed if the AA and rKA were chosen.

CONCLUSION

Compared with the CPAK, the functional knee phenotypes were more suitable for the Chinese OA population with a wide distribution and a varus tendency, and it seemed more appropriate to choose aMA and rKA as TKA alignment targets for resection.

LEVEL OF EVIDENCE

Level Ⅲ.

Functional alignment in robotic-assisted total knee arthroplasty: a systematic review

PURPOSE

The present study systematically reviewed current evidence on functional alignment (FA) in robotic total knee arthroplasty (TKA), discussing advantages and limitations, possible pitfalls, and prospects.

METHODS

This study was conducted according to the 2020 PRISMA statement. In August 2023, the following databases were accessed: PubMed, Web of Science, Google Scholar, and Embase with no additional filters or time constraints. All the clinical studies investigating functional alignment in robotic TKA were accessed. Only studies published in peer-reviewed journals were considered. The risk of bias was evaluated following the guidelines in the Cochrane Handbook for Systematic Reviews of Interventions. Non-randomized controlled trials (non-RCTs) were evaluated using the Risk of Bias in Nonrandomised Studies of Interventions (NRSI) (ROBINS-I) tool.

RESULTS

Data from 1198 patients (seven studies) were retrieved. The mean length of the follow-up was 17.1 ± 6.4 months. The mean age was 67.2 ± 5.4 years, and the mean BMI was 30.9 ± 2.7 kg/m2.

CONCLUSION

FA might improve resection accuracy, implant alignment, and gap balancing in TKA, and additional high-quality clinical trials are necessary to properly establish the superiority of FA to other alignment techniques in TKA. Long-term clinical trials are needed to investigate the impact of FA on implant survivorship.

LEVEL OF EVIDENCE

Level IV, systematic review and meta-analysis.

Level I of evidence does not support manual lymphatic drainage for total knee arthroplasty: a meta-analysis

It is unclear whether manual lymphatic drainage (MLD) following primary total knee arthroplasty (TKA) is effective in reducing pain and swelling and improving knee function. The present study investigated the efficacy of MLD after TKA. The outcomes of interest are the range of motion (ROM), pain (visual analogue scale, VAS), and circumference of the lower leg. This meta-analysis was conducted according to the 2020 PRISMA statement. In November 2023, the following databases were accessed: PubMed, Web of Science, Google Scholar, and Embase, with no time constraint. Only level I evidence studies, according to the Oxford Centre of Evidence-Based Medicine, were considered. All the randomised controlled trials (RCTs) comparing patients who have received MLD versus a group of patients who did not undergo MLD following primary TKA were accessed. Data from four RCTs (197 TKAs) were retrieved. 67% (132 of 197 patients) were women. The mean length of follow-up was 7.0 ± 5.8 weeks. The mean age of the patients was 69.6 ± 2.7 years, and the mean BMI was 28.7 ± 0.9 kg/m2. At baseline, between-group comparability was evidenced in the male:female ratio, mean age, mean BMI, knee flexion, and VAS. No difference was found in flexion (P = 0.7) and VAS (P = 0.3). No difference was found in the circumference of the thigh (P = 0.8), knee (P = 0.4), calf (P = 0.4), and ankle (P = 0.3). The current level I of evidence does not support the use of MLD in primary TKA.

Optimal Sequence of Corrective Surgeries for Concomitant Valgus Knee and Rigid Pes Planus Deformities: The Knee-First Approach

In patients requiring surgical correction of ipsilateral valgus knee and rigid pes planovalgus deformities, the optimal operative sequence is controversial. Growing evidence suggests these 2 deformities are related in etiology and interrelated in disease course. We present the case of a 72-year-old female with concomitant valgus knee and rigid pes planovalgus deformities successfully treated with total knee arthroplasty followed by triple arthrodesis and Achilles lengthening. Surgical correction of these deformities must be carefully planned between the operating surgeons to avoid over- or under-correction of alignment that could further impact gait. In contrast with the limited available literature, the authors recommend correction at the knee first and the foot and ankle second. Further prospective studies are needed to elucidate the best operative sequence in these patients.

Fostering Excellence in Knee Arthroplasty: Developing Optimal Patient Care Pathways and Inspiring Knowledge Transfer of Advanced Surgical Techniques

Osteoarthritis of the knee is common. Early sports trauma or cartilage defects are risk factors for osteoarthritis. If conservative treatment fails, partial or total joint replacement is often performed. A joint replacement aims to restore physiological biomechanics and the quality of life of affected patients. Total knee arthroplasty is one of the most performed surgeries in musculoskeletal medicine. Several developments have taken place over the last decades that have truly altered the way we look at knee arthroplasty today. Some of the fascinating aspects will be presented and discussed in the present narrative review.

The landscape of surgical robotics in orthopedics surgery

Orthopedic surgery is one of the first surgical specialties to apply surgical robotics in clinical practice, which has become an interesting field over the years with promising results. Surgical robotics can facilitate total joint arthroplasty by providing robotic support to accurately prepare the bone, improving the ability to reproduce alignment, and restoring normal kinematics. Various robotic systems are available on the market, each tailored to specific types of surgeries and characterized by a series of features with different requirements and/or modus operandi. Here, a narrative review of the current state of surgical robotic systems for total joint knee arthroplasty is presented, covering the different categories of robots, which are classified based on the operation, requirements, and level of interaction with the surgeon. The different robotic systems include closed/open platform, image-based/imageless, and passive/active/semi-active systems. The main goal of a robotic system is to increase the accuracy and precision of the operation regardless of the type of system. Despite the short history of surgical robots, they have shown clinical effectiveness compared to conventional techniques in orthopedic surgery. When considering which robotic system to use, surgeons should carefully evaluate the different benefits and drawbacks to select the surgical robot that fits their needs the best.