Custom TKA enables adequate realignment with minimal ligament release and grants satisfactory outcomes in knees that had prior osteotomies or extra-articular fracture sequelae

How New Technologies Will Transform Total Knee Arthroplasty from a Singular Surgical Procedure to a Holistic Standardized Process

Many new technologies focused mainly on improving surgical accuracy were first developed in total knee arthroplasty and have not yet shown significant value. These non-significant clinical improvements could potentially be explained by an inadequate target. In this current concept paper, the authors will describe how artificial intelligence (AI), robotic-assisted surgery, and custom implants allow the definition of new targets and the standardization of the TKA process. As paradoxical as it may be, new technologies in TKA will allow for better standardization in the overall way in which this procedure is carried out. Achieving this goal can be accomplished by incorporating AI-driven tools into the medical field. These tools are intended to enhance decision making, refine surgical planning, and increase the precision and consistency of surgical procedures. Moreover, custom implants with personalized alignment, beyond restoring native anatomy, will define new targets and standardize the whole TKA process.

Patient-reported outcome measures following individualised TKA are not affected by the degree of preoperative coronal varus or valgus laxity

PURPOSE

To determine whether there is a correlation between preoperative coronal varus or valgus laxity and patient-reported outcome measures (PROMs) 2 years after individualised total knee arthroplasty (TKA).

METHODS

Records of 150 consecutive patients who received individualised TKA were retrospectively analysed, and 126 with complete pre- and postoperative data were included. Preoperative coronal varus and valgus stress radiographs (15 N load) were taken using a telos stress device with the knee in 5°-10° of flexion. Varus stress angles were positive if the joint opened on the lateral side, and valgus stress angles were positive if the joint opened on the medial side. The sum of varus and valgus stress angles indicated total joint laxity. During surgery, cases that required tibial recuts to balance the joint were recorded. Patients completed three PROMs and rated their satisfaction. Correlations between laxity and PROMs were evaluated using Pearson's correlation.

RESULTS

Stress radiographs revealed varus stress angles of 6.3° ± 3.5° (range, -4.5° to 14.1°), valgus stress angles of 0.1° ± 3.7° (range, -8.0° to 10.9°), and the sum of the varus and valgus stress angle of 6.4° ± 3.3° (range, 0.1° to 17.1°). There were no correlations between laxity and PROMs: r < 0.160 for varus stress angle, r < 0.180 for valgus stress angle and r < 0.160 for the sum of stress angles. There were no statistically significant or clinically relevant differences in PROMs between knees without and those with tibial recuts.

CONCLUSION

Preoperative coronal varus or valgus laxity was not correlated with PROMs following individualised TKA at a minimum 2-year follow-up. Individualised TKA with personalised alignment enables adequate accommodation of a broad spectrum of preoperative coronal varus-valgus laxities.

LEVEL OF EVIDENCE

Level IV.

Custom total knee arthroplasty with personalised alignment showed better 2-year functional outcome compared to off-the-shelf arthroplasty

PURPOSE

Customised individually made (CIM) total knee arthroplasty (TKA) with personalised alignment is relatively new and evidence is limited. The aim of this study was to compare patient-reported outcome measures between CIM and off-the-shelf (OTS) TKA patients in a matched-pair analysis with a 2-year follow-up.

METHODS

In this single-centre, prospective cohort study, propensity score matching was performed on 51 CIM and 51 OTS TKA. Data were measured at baseline, at 4 months, 1 and 2 years and included the Forgotten Joint Score (FJS-12), the High Activity Arthroplasty Score (HAAS), the Knee injury and Osteoarthritis Outcome Score (KOOS), the EQ-5D-3L, the EQ-Visual Analogue Scale, satisfaction, overall knee improvement, willingness to undergo the surgery again and the Knee Society Score.

RESULTS

At 2 years follow-up, the FJS-12 (77 vs. 67, p = .058), HAAS (13 vs. 11, p < .001), KOOS daily living (92 vs. 86, p = .029), KOOS sport (76 vs. 65, p = .019), KOOS quality of life (81 vs. 71, p = .028) and the EQ-5D (.95 vs. .90, p = .030) were higher for CIM TKA compared to OTS TKA. Satisfaction rate was 92% for CIM TKA and 84% for OTS TKA (p = .357). Most patients reported an improvement in the overall knee state (94% CIM and 90% OTS, p = .487) and almost all patients would undergo the surgery again (96% CIM and 98% OTS, p = .999).

CONCLUSION

The current study found that CIM TKA patients had better functional outcomes at 2 years. Patient satisfaction was high and not statistically significantly different from OTS TKA patients.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Satisfaction after total knee arthroplasty: a prospective matched-pair analysis of patients with customised individually made and off-the-shelf implants

PURPOSE

Customised individually made (CIM) total knee arthroplasty (TKA) was introduced to potentially improve patient satisfaction and other patient-reported outcome measures (PROMs). The purpose of this study was to compare PROMs, especially patient satisfaction, of patients with CIM and OTS TKA in a matched-pair analysis with a 2-year follow-up.

METHODS

This is a prospective cohort study with a propensity score matching of 85 CIM and 85 off-the-shelf (OTS) TKA. Follow-up was at 4 months, 1 year and 2 years. The primary outcome was patient satisfaction. Secondary outcomes were as follows: overall improvement, willingness to undergo the surgery again, Knee injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score (FJS-12), High-Activity Arthroplasty Score (HAAS), EQ-5D-3L, EQ-VAS, Knee Society Score (KSS) and surgeon satisfaction.

RESULTS

Patient satisfaction ranged from 86 to 90% and did not differ between CIM and OTS TKA. The EQ-VAS after 4 months and the HAAS after 1 year and 2 years were higher for CIM TKA. KOOS, FJS-12 and EQ-5D-3L were not different at follow-up. The changes in KOOS symptoms, pain and daily living were higher for OTS TKA. The KSS was higher for patients with CIM TKA. Surgeon satisfaction was high throughout both groups. Patients who were satisfied after 2 years did not differ preoperatively from those who were not satisfied. Postoperatively, all PROMs were better for satisfied patients. Patient satisfaction was not correlated with patient characteristics, implant or preoperative PROMs, and medium to strongly correlated with postoperative PROMs.

CONCLUSION

Patient satisfaction was high with no differences between patients with CIM and OTS TKA. Both implant systems improved function, pain and health-related quality of life. Patients with CIM TKA showed superior results in demanding activities as measured by the HAAS.

LEVEL OF EVIDENCE

II, prospective cohort study.

The coronal plane alignment of the knee classification does not correlate with the functional knee phenotype classification

PURPOSE

It is now well established that the coronal anatomy of the lower limb is highly variable both in non-arthritic subjects and subjects undergoing total knee arthroplasty (TKA). Two new classifications were recently described independently, but never compared: functional knee phenotypes classification and coronal plane alignment of the knee (CPAK) classification. The hypothesis of this study was that there was a significant difference between the values of the hip-knee-ankle angle (HKA) and the arithmetic hip-knee-ankle angle (aHKA) measures in the same patient at the time of TKA.

METHODS

Five hundred and twenty cases were randomly selected among patients operated on for a TKA with navigation assistance. Anatomical parameters were collected during surgery by a navigation system, and the corresponding data of the CPAK classification were calculated. The numerical values of measured HKA and aHKA in the same patient were compared.

RESULTS

The measured HKA had a mean of 3.0° varus (standard deviation of 6.0°). The calculated aHKA had a mean of 1.8° varus (standard deviation 4.8°). There was a significant difference between the values of the two measurements in the same subject (p = 0.005) and a weak negative correlation between the values of the two measurements in the same subject. In addition, there was no relationship between HKA values and joint line obliquity values or CPAK class.

CONCLUSION

A significant difference and a weak correlation between the values of the HKA and aHKA measures in the same subject were observed. The two analysis techniques used provide different information, and their correlation is only partial. These two techniques therefore appear to be complementary rather than exclusive. The clinical relevance of using these techniques during TKA remains unknown.

LEVEL OF EVIDENCE

III.

Improved Knee Function with Customized vs. Off-the-Shelf TKA Implants-Results of a Single-Surgeon, Single-Center, Single-Blinded Study

BACKGROUND

Recent studies have been able to show certain benefits of Customized, Individually Made (CIM) compared to Off-the-Shelf (OTS) total knee arthroplasties (TKAs), but evidence is still lacking regarding the benefits of these implant systems. This study aimed to find differences in scores and functional outcome by comparing CIM and OTS implants, using Patient-Reported Outcome Measures (PROMs) and functional tests for activities of daily living in a single-surgeon setup.

METHODS

A total of 48 patients (16 CIM vs. 32 OTS) were consecutively enrolled and blindly examined. Functional testing was performed using four timed functional tests (TUG, WALK, TUDS, and BBS) and the VAS for pain. The Aggregated Locomotor Function (ALF) score was then calculated based on the addition of the average times of the three functional tests.

RESULTS

The CIM group showed significantly faster times in all functional tests and significantly better ALF scores. There were remarkable differences in the assessment of maximum pain sensation between the two groups, with superiority in the CIM group. The PROMs analysis revealed a higher proportion of excellent and good ratings for the items objective and function (KSS) in the CIM group.

CONCLUSION

The study showed that time-limited activities of daily living (ADLs) can be completed significantly faster with a CIM prosthesis and that a significantly higher percentage in this group reports freedom from pain during certain loads. Partial aspects of the PROM scores are also better in this group; however, this superiority could not be shown with regard to most PROM scores collected in this study.

Patient Specific Instruments and Patient Individual Implants—A Narrative Review

Joint arthroplasties are one of the most frequently performed standard operations worldwide. Patient individual instruments and patient individual implants represent an innovation that must prove its usefulness in further studies. However, promising results are emerging. Those implants seem to be a benefit especially in revision situations. Most experience is available in the field of knee and hip arthroplasty. Patient-specific instruments for the shoulder and upper ankle are much less common. Patient individual implants combine individual cutting blocks and implants, while patient individual instruments solely use individual cutting blocks in combination with off-the-shelf implants. This review summarizes the current data regarding the implantation of individual implants and the use of individual instruments.