Aims

The primary aim was to assess whether robotic total knee arthroplasty (rTKA) had a greater early knee-specific outcome when compared to manual TKA (mTKA). Secondary aims were to assess whether rTKA was associated with improved expectation fulfilment, health-related quality of life (HRQoL), and patient satisfaction when compared to mTKA.

Aims. Intraoperative pressure sensors allow surgeons to quantify soft-tissue balance during total knee arthroplasty (TKA). The aim of this study was to determine whether using sensors to achieve soft-tissue balance was more effective than manual balancing in improving outcomes in TKA. Methods. A multicentre randomized trial compared the outcomes of sensor balancing (SB) with manual balancing (MB) in 250 patients (285 TKAs). The primary outcome measure was the mean difference in the four Knee injury and Osteoarthritis Outcome Score subscales (ΔKOOS. 4. ) in the two groups, comparing the preoperative and two-year scores. Secondary outcomes included intraoperative balance data, additional patient-reported outcome measures (PROMs), and functional measures. Results. There was no significant difference in ΔKOOS. 4. between the two groups at two years (mean difference 0.4 points (95% confidence interval (CI) -4.6 to 5.4); p = 0.869), and multiple regression found that SB was not associated with a significant ΔKOOS. 4. (0.2-point increase (95% CI -5.1 to 4.6); p = 0.924). There were no significant differences between groups in other PROMs. Six-minute walking distance was significantly increased in the SB group (mean difference 29 metres; p = 0.015). Four-times as many TKAs were unbalanced in the MB group (36.8% MB vs 9.4% SB; p < 0.001). Irrespective of group assignment, no differences were found in any PROM when increasing ICPD thresholds defined balance. Conclusion. Despite improved quantitative soft-tissue balance, the use of sensors intraoperatively did not differentially improve the clinical or functional outcomes two years after TKA. These results question whether a more precisely balanced TKA that is guided by sensor data, and often achieved by more balancing interventions, will ultimately have a significant effect on clinical outcomes. Cite this article: Bone Joint J 2022;104-B(5):604–612

Aims

Neither a surgeon’s intraoperative impression nor the parameters of computer navigation have been shown to be predictive of the outcomes following total knee arthroplasty (TKA). The aim of this study was to determine whether a surgeon, with robotic assistance, can predict the outcome as assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) for pain (KPS), one year postoperatively, and establish what factors correlate with poor KOOS scores in a well-aligned and balanced TKA.

Aims

Patellofemoral problems are a common complication of total knee arthroplasty. A high compressive force across the patellofemoral joint may affect patient-reported outcome. However, the relationship between patient-reported outcome and the intraoperative patellofemoral contact force has not been investigated. The purpose of this study was to determine whether or not a high intraoperative patellofemoral compressive force affects patient-reported outcome.

Recent fluoroscopic analyses evaluating the kinematic function of TKAs have demonstrated significant variability among patients with identical implant designs, suggesting surgical technique also influences function. To help explain these kinematic variations, we used intraoperative compartment pressure sensors to assess balancing at trial reduction and ROM then correlated these intraoperative findings with patients’ postoperative kinematics, assessed using video fluoroscopy. This study involved 16 patients implanted with a posterior cruciate-sacrificing LCS TKA using a balanced gap technique. After releases in extension, the femur was rotated the appropriate amount to create a rectangular flexion gap relative to the cut tibial surface. As the knee was taken through a ROM from 0–120°, the sensors (placed on the tibial insert trial) dynamically measured the magnitude and location of compartment pressures throughout the ROM. Six to nine months postoperatively, all patients performed successive weight-bearing deep knee bends to maximum flexion under fluoroscopic surveillance. Each patient’s femoro-tibial contact positions and liftoff values were compared to their respective intraoperative compartment pressure findings to establish correlations. Fluoroscopic results correlated closely with intraoperative compartment pressures and balance data. Three of the 16 patients had condylar liftoff: two patients experienced liftoff in flexion and one in extension (medial). The patient who experienced medial liftoff in extension had decreased medial compartment pressure and a slight valgus malalignment (7° of anatomic alignment). Two of the 13 patients without liftoff had abnormal compartment pressures in extension. In both cases, mechanical axis alignment resulted in loading of the lax compartment with weight-bearing. The other 11 patients had normal compartment pressures in extension and no condylar liftoff. One of these patients had slight valgus (7°) and another slight varus malalignment (4°), but both had normal compartment pressures. Despite good compartment balance, average tibiofemoral rotation was inadequate; three of 16 patients experienced opposite axial rotation with flexion. Extensive ligament release did not always result in equal compartment pressure magnitudes and distributions; compartment balance was influenced by the nature of the release. These data suggest that liftoff may require both a compartment pressure imbalance and abnormal alignment that together exacerbate the laxity with physiologic loading. Previous kinematic studies of LCS knees have shown that the balanced gap technique produces wellbalanced compartment pressures, resulting in TKAs with little lift-off and very good translational and rotational characteristics. Therefore, while a given implant design may have inherent kinematic tendencies, surgical technique may significantly impact kinematic performance. To optimize implant kinematics and subsequent TKA function and longevity, it may be important for surgeons to accurately balance the flexion and extension gaps. Characteristic compartment pressure patterns and distributions for various ligament releases may shed some light on less than optimal rotational kinematic performance