We investigated the extent to which improved balance relative to pain relief correlates with the success of total knee replacement (TKR). A total of 81 patients were recruited to the study: 16 men (19.8%) and 65 women (80.2%). Of these, 62 patients (10 men, 52 women) with a mean age of 73 (57 to 83) underwent static and dynamic assessment of balance pre-operatively and one year post-operatively. The parameters of balance were quantified using commercially available and validated equipment. Motor function and self-reported outcome were also assessed. There was a significant improvement in dynamic balance (p < 0.001) one year after TKR, and better balance correlated with improved mobility, functional balance and increased health-related quality of life. As it seems that balance, and not only pain relief, influences the success of TKR, balance skills should be better addressed during the post-operative rehabilitation of patients who undergo TKR

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. The use of technology to assess balance and alignment during total knee surgery can provide an overload of numerical data to the surgeon. Meanwhile, this quantification holds the potential to clarify and guide the surgeon through the surgical decision process when selecting the appropriate bone recut or soft tissue adjustment when balancing a total knee. Therefore, this paper evaluates the potential of deploying supervised machine learning (ML) models to select a surgical correction based on patient-specific intra-operative assessments. Methods. Based on a clinical series of 479 primary total knees and 1,305 associated surgical decisions, various ML models were developed. These models identified the indicated surgical decision based on available, intra-operative alignment, and tibiofemoral load data. Results. With an associated area under the receiver-operator curve ranging between 0.75 and 0.98, the optimized ML models resulted in good to excellent predictions. The best performing model used a random forest approach while considering both alignment and intra-articular load readings. Conclusion. The presented model has the potential to make experience available to surgeons adopting new technology, bringing expert opinion in their operating theatre, but also provides insight in the surgical decision process. More specifically, these promising outcomes indicated the relevance of considering the overall limb alignment in the coronal and sagittal plane to identify the appropriate surgical decision

Aims. Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology. Methods. This prospective study included 30 consecutive patients undergoing robotic-assisted TKA using the Stryker PS Triathlon implant with functional alignment. Intraoperative soft-tissue balance was assessed using sensor-guided technology after definitive component implantation; soft-tissue balance was defined as intercompartmental pressure difference (ICPD) of < 15 psi. Medial and lateral compartment pressures were recorded at 10°, 45°, and 90° of knee flexion. This study included 18 females (60%) and 12 males (40%) with a mean age of 65.2 years (SD 9.3). Mean preoperative hip-knee-ankle deformity was 6.3° varus (SD 2.7°). Results. TKA with functional alignment achieved balanced medial and lateral compartment pressures at 10° (25.0 psi (SD 6.1) vs 23.1 psi (SD 6.7), respectively; p = 0.140), 45° (21.4 psi (SD 5.9) vs 20.6 psi (SD 5.9), respectively; p = 0.510), and 90° (21.2 psi (SD 7.1) vs 21.6 psi (SD 9.0), respectively; p = 0.800) of knee flexion. Mean ICPD was 6.1 psi (SD 4.5; 0 to 14) at 10°, 5.4 psi (SD 3.9; 0 to 12) at 45°, and 4.9 psi (SD 4.45; 0 to 15) at 90° of knee flexion. Mean postoperative limb alignment was 2.2° varus (SD 1.0°). Conclusion. TKA using the functional alignment achieves balanced mediolateral soft-tissue tension through the arc of knee flexion as assessed using intraoperative pressure-sensor technology. Further clinical trials are required to determine if TKA with functional alignment translates to improvements in patient satisfaction and outcomes compared to conventional alignment techniques. Cite this article: Bone Joint J 2021;103-B(3):507–514

Aims. A significant percentage of patients remain dissatisfied after total knee arthroplasty (TKA). The aim of this study was to determine whether the sequential addition of accelerometer-based navigation for femoral component preparation and sensor-guided ligament balancing improved complication rates, radiological alignment, or patient-reported outcomes (PROMs) compared with a historical control group using conventional instrumentation. Methods. This retrospective cohort study included 371 TKAs performed by a single surgeon sequentially. A historical control group, with the use of intramedullary guides for distal femoral resection and surgeon-guided ligament balancing, was compared with a group using accelerometer-based navigation for distal femoral resection and surgeon-guided balancing (group 1), and one using navigated femoral resection and sensor-guided balancing (group 2). Primary outcome measures were Patient-Reported Outcomes Measurement Information System (PROMIS) and Knee injury and Osteoarthritis Outcome (KOOS) scores measured preoperatively and at six weeks and 12 months postoperatively. The position of the components and the mechanical axis of the limb were measured postoperatively. The postoperative range of motion (ROM), haematocrit change, and complications were also recorded. Results. There were 194 patients in the control group, 103 in group 1, and 74 in group 2. There were no significant differences in baseline demographics between the groups. Patients in group 2 had significantly higher baseline mental health subscores than control and group 1 patients (53.2 vs 50.2 vs 50.2, p = 0.041). There were no significant differences in any PROMs at six weeks or 12 months postoperatively (p > 0.05). There was no difference in the rate of manipulation under anaesthesia (MUA), complication rates, postoperative ROM, or blood loss. There were fewer mechanical axis outliers in groups 1 and 2 (25.2%, 14.9% respectively) versus control (28.4%), but this was not statistically significant (p = 0.10). Conclusion. The sequential addition of navigation of the distal femoral cut and sensor-guided ligament balancing did not improve short-term PROMs, radiological outcomes, or complication rates compared with conventional techniques. The costs of these added technologies may not be justified. Cite this article: Bone Joint J 2020;102-B(6 Supple A):24–30

Aims. It is unknown whether kinematic alignment (KA) objectively improves knee balance in total knee arthroplasty (TKA), despite this being the biomechanical rationale for its use. This study aimed to determine whether restoring the constitutional alignment using a restrictive KA protocol resulted in better quantitative knee balance than mechanical alignment (MA). Methods. We conducted a randomized superiority trial comparing patients undergoing TKA assigned to KA within a restrictive safe zone or MA. Optimal knee balance was defined as an intercompartmental pressure difference (ICPD) of 15 psi or less using a pressure sensor. The primary endpoint was the mean intraoperative ICPD at 10° of flexion prior to knee balancing. Secondary outcomes included balance at 45° and 90°, requirements for balancing procedures, and presence of tibiofemoral lift-off. Results. A total of 63 patients (70 knees) were randomized to KA and 62 patients (68 knees) to MA. Mean ICPD at 10° flexion in the KA group was 11.7 psi (SD 13.1) compared with 32.0 psi in the MA group (SD 28.9), with a mean difference in ICPD between KA and MA of 20.3 psi (p < 0.001). Mean ICPD in the KA group was significantly lower than in the MA group at 45° and 90°, respectively (25.2 psi MA vs 14.8 psi KA, p = 0.004; 19.1 psi MA vs 11.7 psi KA, p < 0.002, respectively). Overall, participants in the KA group were more likely to achieve optimal knee balance (80% vs 35%; p < 0.001). Bone recuts to achieve knee balance were more likely to be required in the MA group (49% vs 9%; p < 0.001). More participants in the MA group had tibiofemoral lift-off (43% vs 13%; p < 0.001). Conclusion. This study provides persuasive evidence that restoring the constitutional alignment with KA in TKA results in a statistically significant improvement in quantitative knee balance, and further supports this technique as a viable alternative to MA. Cite this article: Bone Joint J. 2020;102-B(1):117–124

Aims. The results of kinematic total knee arthroplasty (KTKA) have been reported in terms of limb and component alignment parameters but not in terms of gap laxities and differentials. In kinematic alignment (KA), balance should reflect the asymmetrical balance of the normal knee, not the classic rectangular flexion and extension gaps sought with gap-balanced mechanical axis total knee arthroplasty (MATKA). This paper aims to address the following questions: 1) what factors determine coronal joint congruence as measured on standing radiographs?; 2) is flexion gap asymmetry produced with KA?; 3) does lateral flexion gap laxity affect outcomes?; 4) is lateral flexion gap laxity associated with lateral extension gap laxity?; and 5) can consistent ligament balance be produced without releases?. Patients and Methods. A total of 192 KTKAs completed by a single surgeon using a computer-assisted technique were followed for a mean of 3.5 years (2 to 5). There were 116 male patients (60%) and 76 female patients (40%) with a mean age of 65 years (48 to 88). Outcome measures included intraoperative gap laxity measurements and component positions, as well as joint angles from postoperative three-foot standing radiographs. Patient-reported outcome measures (PROMs) were analyzed in terms of alignment and balance: EuroQol (EQ)-5D visual analogue scale (VAS), Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS Joint Replacement (JR), and Oxford Knee Score (OKS). Results. Postoperative limb alignment did not affect outcomes. The standing hip-knee-ankle (HKA) angle was the sole positive predictor of the joint line convergence angle (JLCA) (p < 0.001). Increasing lateral flexion gap laxity was consistently associated with better outcomes. Lateral flexion gap laxity did not correlate with HKA angle, the JLCA, or lateral extension gap laxity. Minor releases were required in one third of cases. Conclusion. The standing HKA angle is the primary determinant of the JLCA in KTKA. A rectangular flexion gap is produced in only 11% of cases. Lateral flexion gap laxity is consistently associated with better outcomes and does not affect balance in extension. Minor releases are sometimes required as well, particularly in limbs with larger preoperative deformities. Cite this article: Bone Joint J 2019;101-B:331–339

We have investigated whether control of balance is improved during stance and gait and sit-to-stand tasks after unilateral total hip replacement undertaken for osteoarthritis of the hip. We examined 25 patients with a mean age of 67 years (. sd. 6.2) before and at four and 12 months after surgery and compared the findings with those of 50 healthy age-matched control subjects. For all tasks, balance was quantified using angular measurements of movement of the trunk. Before surgery, control of balance during gait and sit-to-stand tasks was abnormal in patients with severe osteoarthritis of the hip, while balance during stance was similar to that of the healthy control group. After total hip replacement, there was a progressive improvement at four and 12 months for most gait and sit-to-stand tasks and in the time needed to complete them. By 12 months, the values approached those of the control group. However, trunk pitch (forwards-backwards) and roll (side-to-side) velocities were less stable (greater than the control) when walking over barriers as was roll for the sit-to-stand task, indicative of a residual deficit of balance. Our data suggest that patients with symptomatic osteoarthritis of the hip have marked deficits of balance in gait tasks, which may explain the increased risk of falling which has been reported in some epidemiological studies. However, total hip replacement may help these patients to regain almost normal control of balance for some gait tasks, as we found in this study. Despite the improvement in most components of balance, however, the deficit in the control of trunk velocity during gait suggests that a cautious follow-up is required after total hip replacement regarding the risk of a fall, especially in the elderly

Aims. High-grade dysplastic spondylolisthesis is a disabling disorder for which many different operative techniques have been described. The aim of this study is to evaluate Scoliosis Research Society 22-item (SRS-22r) scores, global balance, and regional spino-pelvic alignment from two to 25 years after surgery for high-grade dysplastic spondylolisthesis using an all-posterior partial reduction, transfixation technique. Methods. SRS-22r and full-spine lateral radiographs were collected for the 28 young patients (age 13.4 years (SD 2.6) who underwent surgery for high-grade dysplastic spondylolisthesis in our centre (Scottish National Spinal Deformity Service) between 1995 and 2018. The mean follow-up was nine years (2 to 25), and one patient was lost to follow-up. The standard surgical technique was an all-posterior, partial reduction, and S1 to L5 transfixation screw technique without direct decompression. Parameters for segmental (slip percentage, Dubousset’s lumbosacral angle) and regional alignment (pelvic tilt, sacral slope, L5 incidence, lumbar lordosis, and thoracic kyphosis) and global balance (T1 spino-pelvic inclination) were measured. SRS-22r scores were compared between patients with a balanced and unbalanced pelvis at final follow-up. Results. SRS-22r domain and total scores improved significantly from preoperative to final follow-up, except for the mental health domain that remained the same. Slip percentage improved from 75% (SD 15) to 48% (SD 19) and lumbosacral angle from 70° (SD 11) to 101° (SD 11). Preoperatively, 35% had global imbalance, and at follow-up all were balanced. Preoperatively, 63% had an unbalanced pelvis, and at final follow-up this was 32%. SRS-22r scores were not different in patients with a balanced or unbalanced pelvis. However, postoperative pelvic imbalance as measured by L5 incidence was associated with lower SRS-22r self-image and total scores (p = 0.029). Conclusion. In young patients with HGDS, partial reduction and transfixation improves local lumbosacral alignment, restores pelvic, and global balance and provides satisfactory long-term clinical outcomes. Higher SRS-22r self-image and total scores were observed in the patients that had a balanced pelvis (L5I < 60°) at two to 25 years follow-up. Cite this article: Bone Jt Open 2021;2(3):163–173

Smart trials are total knee tibial trial liners with load bearing and alignment sensors that will graphically show quantitative compartment load-bearing forces and component track patterns. These values will demonstrate asymmetrical ligament balancing and misalignments with the medial retinaculum temporarily closed. Currently surgeons use feel and visual estimation of imbalance to assess soft-tissue balancing and tracking with the medial retinaculum open, which results in lower medial compartment loads and a wider anteroposterior tibial tracking pattern. The sensor trial will aid the total knee replacement surgeon in performing soft-tissue balancing by providing quantitative visual feedback of changes in forces while performing the releases incrementally. Initial experience using a smart tibial trial is presented

We studied the influence of soft-tissue releases and soft-tissue balance on the outcome of 526 total knee replacements one year after operation. The surgery had been performed by seven surgeons in five centres in the United Kingdom between October 1999 and December 2002. Balancing was carried out by five surgeons using spacers and trials and by two surgeons using a ‘balancer’ instrument. All the surgeons assessed the adequacy of their releases by taking measurements with the balancer after soft-tissue release before implanting the components. Independent observers collected the Oxford knee scores and applied the American Knee Society functional and knee scores as well as recording the range of movement of the replaced knee. These were compared with the pre-operative scores and the extent of the releases. We found differences in outcomes between minimal and extensive releases and between balanced and imbalanced knees. Knees requiring extensive soft-tissue releases showed greater change in the short-term clinical outcome without increased complications and achieved similar results at one year compared with those with less deformity pre-operatively which had required less soft-tissue release. Balancing an imbalanced knee improved the short-term knee outcome

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.

Objectives. The objective of this study was to assess the association between whole body sagittal balance and risk of falls in elderly patients who have sought treatment for back pain. Balanced spinal sagittal alignment is known to be important for the prevention of falls. However, spinal sagittal imbalance can be markedly compensated by the lower extremities, and whole body sagittal balance including the lower extremities should be assessed to evaluate actual imbalances related to falls. Methods. Patients over 70 years old who visited an outpatient clinic for back pain treatment and underwent a standing whole-body radiograph were enrolled. Falls were prospectively assessed for 12 months using a monthly fall diary, and patients were divided into fallers and non-fallers according to the history of falls. Radiological parameters from whole-body radiographs and clinical data were compared between the two groups. Results. A total of 144 patients (120 female patients and 24 male patients) completed a 12-month follow-up for assessing falls. A total of 31 patients (21.5%) reported at least one fall within the 12-month follow-up. In univariate logistic regression analysis, the risk of falls was significantly increased in older patients and those with more medical comorbidities, decreased lumbar lordosis, increased sagittal vertical axis, and increased horizontal distance between the C7 plumb line and the centre of the ankle (C7A). Increased C7A was significantly associated with increased risk of falls even after multivariate adjustment. Conclusion. Whole body sagittal balance, measured by the horizontal distance between the C7 plumb line and the centre of the ankle, was significantly associated with risk of falls among elderly patients with back pain. Cite this article: J. Kim, J. Y. Hwang, J. K. Oh, M. S. Park, S. W. Kim, H. Chang, T-H. Kim. The association between whole body sagittal balance and risk of falls among elderly patients seeking treatment for back pain. Bone Joint Res 2017;6:–344. DOI: 10.1302/2046-3758.65.BJR-2016-0271.R2

Aims

Functional alignment (FA) in total knee arthroplasty (TKA) aims to achieve balanced gaps by adjusting implant positioning while minimizing changes to constitutional joint line obliquity (JLO). Although FA uses kinematic alignment (KA) as a starting point, the final implant positions can vary significantly between these two approaches. This study used the Coronal Plane Alignment of the Knee (CPAK) classification to compare differences between KA and final FA positions.

Aims

The aim was to assess whether robotic-assisted total knee arthroplasty (rTKA) had greater knee-specific outcomes, improved fulfilment of expectations, health-related quality of life (HRQoL), and patient satisfaction when compared with manual TKA (mTKA).

Decreasing proprioception of the knee is multifactorial and is a function of age and degenerative joint disease. Soft-tissue release during total knee replacement may have an influence. We have quantified soft-tissue imbalance at the time of knee replacement and attempted to eliminate it at full extension, using established methods. We studied the influence of residual soft-tissue imbalance on postoperative proprioception, assessing this in 38 patients before total knee replacement and at three and six months postoperatively. We found that proprioception improved in varus knees at three and six months after soft-tissue balancing procedures. Knees balanced in full extension and in flexion (< ±2°) showed a significant improvement in proprioception (p < 0.0005) whereas those which were not balanced in flexion but fully balanced in extension had no significant improvement. We conclude that soft-tissue balance in both flexion and extension is important to allow satisfactory postoperative proprioception of the knee

We performed a randomised, prospective study of 80 mobile-bearing total knee arthroplasties (80 knees) in order to measure the effects of varus-valgus laxity and balance on the range of movement (ROM) one year after operation. Forty knees had a posterior-cruciate-ligament (PCL)-retaining prosthesis and the other 40 a PCL-sacrificing prosthesis. In the balanced group (69 knees) in which the difference between varus and valgus was less than 2°, the mean ROM improved significantly from 107.6° to 117.7° (p < 0.0001). By contrast, in the 11 knees which were unbalanced and in which the difference between varus and valgus laxity exceeded 2°, the ROM decreased from a mean of 121.0° to 112.7° (p = 0.0061). We conclude that coronal laxity, especially balanced laxity, is important for achieving an improved ROM in mobile-bearing total knee arthroplasty

We reviewed two similar groups of patients with medial osteoarthritis of the knee treated by unicompartmental arthroplasty. The group receiving an Oxford meniscal-bearing implant, with no medial release, showed significantly better mechanical alignment than that receiving a fixed-bearing implant. Under-correction, with its ominous mechanical implications, was much more common with the fixed-bearing design. Over-correction was rare and was seen in both designs about equally. Degenerative stenosis of the intercondylar notch was common and appeared to put the anterior cruciate ligament at risk of rupture, especially after correction of the varus deformity. We consider that postoperative leg alignment and soft-tissue balance after unicompartmental knee replacement are determined more by the implant design and the surgical technique than by any variation in soft-tissue contracture. Release of the medial collateral ligament is not necessary for realignment, but a generous notchplasty is often needed to allow normal anterior cruciate ligament function

We operated on 111 patients with 159 congenital club feet with the aim of correcting the deformity and achieving dynamic muscle balance. Clinical and biomechanical assessment was undertaken at least six years after operation when the patient was more than 13 years of age. The mean follow-up was for 11 years 10 months (6 to 36 years). Good and excellent results were obtained in 91.8%. Patients with normal function of the calf had a better outcome than those with weak calf muscles. The radiological changes were assessed in relation to the clinical outcome. The distribution of pressure under the foot was measured for biomechanical assessment. Our results support the view that muscle imbalance is an aetiological factor in club foot. Early surgery seems to be preferable. It is suggested that operation should be undertaken as soon as possible after the age of six months, although it may be carried out up to the age of five years. The establishment of dynamic muscle balance appears to be an effective method of maintaining correction. Satisfactory long-term results can be achieved with adequate appearance and function

We studied a cohort of 26 diabetic patients with chronic ulceration under the first metatarsal head treated by a modified Jones extensor hallucis longus and a flexor hallucis longus transfer. If the first metatarsal was still plantar flexed following these two transfers, a peroneus longus to the peroneus brevis tendon transfer was also performed. Finally, if ankle dorsiflexion was < 5° with the knee extended, a Strayer-type gastrocnemius recession was performed. The mean duration of chronic ulceration despite a minimum of six months’ conservative care was 16.2 months (6 to 31). A total of 23 of the 26 patients were available for follow-up at a mean of 39.6 months (12 to 61) after surgery. All except one achieved complete ulcer healing at a mean of 4.4 weeks (2 to 8) after surgery, and there was no recurrence of ulceration under the first metatarsal. We believe that tendon balancing using modified Jones extensor hallucis longus and flexor hallucis longus transfers, associated in selected cases with a peroneus longus to brevis transfer and/or Strayer procedure, can promote rapid and sustained healing of chronic diabetic ulcers under the first metatarsal head