Robotic-assisted unicompartmental knee arthroplasty has a greater early functional outcome when compared to manual total knee arthroplasty for isolated medial compartment arthritis

American Academy of Orthopaedic Surgeons Clinical Practice Guideline Summary of Surgical Management of Osteoarthritis of the Knee

The Surgical Management of Osteoarthritis of the Knee Evidence-Based Clinical Practice Guideline is based on a systematic review of published studies for surgical management of osteoarthritis of the knee in skeletally mature patients. This guideline contains 16 recommendations and seven options to assist orthopaedic surgeons and all qualified physicians with the surgical management of patients with osteoarthritis of the knee based on the best current available evidence. It is also intended to serve as an information resource for professional healthcare practitioners and developers of practice guidelines and recommendations. In addition to providing pragmatic practice recommendations, this guideline also highlights gaps in the literature and informs areas for future research and quality measure development.

Length of stay and discharge dispositions following robotic arm-assisted total knee arthroplasty and unicompartmental knee arthroplasty versus conventional technique and predictors of delayed discharge

Aims

In-hospital length of stay (LOS) and discharge dispositions following arthroplasty could act as surrogate measures for improvement in patient pathways, and have major cost saving implications for healthcare providers. With the ever-growing adoption of robotic technology in arthroplasty, it is imperative to evaluate its impact on LOS. The objectives of this study were to compare LOS and discharge dispositions following robotic arm-assisted total knee arthroplasty (RO TKA) and unicompartmental arthroplasty (RO UKA) versus conventional technique (CO TKA and UKA).

Methods

This large-scale, single-institution study included patients of any age undergoing primary TKA (n = 1,375) or UKA (n = 337) for any cause between May 2019 and January 2023. Data extracted included patient demographics, LOS, need for post anaesthesia care unit (PACU) admission, anaesthesia type, readmission within 30 days, and discharge dispositions. Univariate and multivariate logistic regression models were also employed to identify factors and patient characteristics related to delayed discharge.

Results

The median LOS in the RO TKA group was 76 hours (interquartile range (IQR) 54 to 104) versus 82.5 (IQR 58 to 127) in the CO TKA group (p < 0.001) and 54 hours (IQR 34 to 77) in the RO UKA versus 58 (IQR 35 to 81) in the CO UKA (p = 0.031). Discharge dispositions were comparable between the two groups. A higher percentage of patients undergoing CO TKA required PACU admission (8% vs 5.2%; p = 0.040).

Conclusion

Our study showed that robotic arm assistance was associated with a shorter LOS in patients undergoing primary UKA and TKA, and no difference in the discharge destinations. Our results suggest that robotic arm assistance could be advantageous in partly addressing the upsurge of knee arthroplasty procedures and the concomitant healthcare burden; however, this needs to be corroborated by long-term cost-effectiveness analyses and data from randomized controlled studies.

Robotic Versus Conventional Unicompartmental Knee Surgery: A Comprehensive Systematic Review and Meta-Analysis

Robotic-assisted surgery is a computer-controlled technique that may improve the accuracy and outcomes of unicompartmental total knee arthroplasty (TKA), a partial knee replacement surgery. The purpose of a meta-analysis about robotic-assisted versus conventional surgery for unicompartmental TKA is to compare the effectiveness of these two methods based on the current evidence. Our meta-analysis can help inform clinical decisions and guidelines for surgeons and patients who are considering unicompartmental TKA as a treatment option. We searched four online databases for studies that compared the two methods until March 2023. We used RevMan software to combine the data from the studies. We calculated the mean difference (MD) and the 95% confidence interval (CI) for each outcome, which are statistical measures of the difference and the uncertainty between the two methods. We included 16 studies in our analysis. We found that robotic-assisted surgery had a better hip-knee-ankle angle, which is a measure of how well the knee is aligned, than conventional surgery (MD = 0.86, 95% CI = 0.16-1.56). We also found that robotic-assisted surgery had a better Oxford Knee score, which is a measure of how well the knee functions, than conventional surgery (MD = 3.03, 95% CI = 0.96-5.110). This study compared the results of conventional and robotic-assisted unicompartmental knee arthroplasty in 12 studies. We concluded that robotic-assisted surgery may have some benefits over conventional surgery in terms of alignment and function of the knee. However, we did not find any significant difference between the two methods in terms of other outcomes, such as pain, range of motion, health status, and joint awareness. Therefore, we suggest that more research is needed to confirm these results and evaluate the long-term effects and cost-effectiveness of robotic-assisted surgery.

Early muscle recovery following robotic-assisted unicompartmental knee arthroplasty

BACKGROUND

Robotic-assisted unicompartmental knee arthroplasty (UKA) improves implant accuracy, however whether this translates to patient function is less clear. Various outcomes have been reported but muscle recovery has not been previously investigated.

OBJECTIVE

To explore sequential change in lower limb muscle strength following robotic-assisted UKA with isokinetic dynamometry.

RESULTS

12 participants undergoing rUKA for medial compartment osteoarthritis were assessed pre-operatively, and at 6- and 12-weeks post-operatively. Maximal muscle strength changed over time in both quadriceps (p = 0.006) and hamstrings (p = 0.018) muscle groups. Quadriceps strength reduced from 88.52(39.86)Nm to 74.47(27.58)Nm by 6-weeks (p = 0.026), and then recovered to 90.41(38.76)Nm by 12-weeks (p = 0.018). Hamstring strength reduced from 62.45(23.18)Nm to 54.12(20.49)Nm by 6-weeks (p = 0.016), and then recovered to 55.07(17.99)Nm by 12-weeks (p = 0.028). By 12-weeks quadriceps strength was 70% and hamstrings 83% of the values achieved in the un-operated limb. Substantial improvement was seen in all other measures over time, with sequential positive change in Timed-up-and-go test (p = 0.015), 10 m walk test (p = 0.021), range of knee flexion (p = 0.016) and PROMs (p < 0.025).

Long-term study of functional outcomes of robotic assisted medial UKA using mid-vastus approach in a high-volume centre

Robotic UKA is one of the recent advancement in surgical management for medial compartment knee osteoarthritis. Over the years, there have been many studies which have showed results of various conventional UKA, high tibial osteotomy and even robotic uka for medial OA of knee all over the world. But still there is very less work on long-term outcome-based analysis of functional outcomes of robotic assisted medial UKA using mid-vastus approach, which was the aim of the study. A total of 680 patients with medial OA knee that were undergone robotic assisted UKA. The study was done at tertiary teaching institute and hospital from November 2016 to October 2022. The assessment of pain, clinical-functional assessment, walking ability, range of motion were assessed by KSS, SF-12 at pre-operatively, mid-term follow-ups and at final follow-up -5.03(± 0.52) years after surgery. 680 patients suited for medial UKA in our study with mean age of 65 ± 10.6 years. Average operating time was 42 ± 4.7 min. The mean postoperative KSS was 93 ± 4.3, the mean SF-12 was 49 ± 9.1, 55 ± 8.7 for PS and MS, respectively. The patient had better KSS and SF-12 when compared pre-operatively and final follow-up (p -0.012 and -9.320, p -0.017 and -7.475, p -0.014 and -5.196, p -0.021 and -7.418, respectively). Complications were also very less. Robotic UKA using mid-vastus approach is effective treatment for medial compartmental OA knee. On short/long-term follow-up of patients, functional and radiological outcomes were good with few complications rates.

Patient Acceptable Symptom State for the Forgotten Joint Score in Primary Total Knee Arthroplasty

BACKGROUND

In order to better understand the clinical benefits of total knee arthroplasty (TKA) and improve the interpretability of the Forgotten Joint Score (FJS-12), the establishment of a meaningful change in score is necessary. The purpose of this study is to determine the threshold of the FJS-12 for detecting the patient acceptable symptom state (PASS) following primary TKA.

METHODS

We retrospectively reviewed all patients who underwent elective, primary TKA and answered both the FJS-12 and the Knee Injury Osteoarthritis Outcome Survey, Joint Replacement KOOS, JR surveys 1-year postoperatively. The questionnaires were administered via a web-based electronic application. KOOS, JR score was used as the anchor. The anchor for PASS calculation should relate pain, physical function, and patient satisfaction. Two statistical methods were employed: (1) the receiver operating characteristic (ROC) curve point; (2) 75^th percentile of the cumulative percentage curve of patients who had the KOOS, JR score difference larger than the cut-off value.

RESULTS

This study included 457 patients. The mean 1-year FJS-12 score was 42.6 ± 27.8. The mean 1-year KOOS, JR score was 68.0 ± 17.2. A high positive correlation between FJS-12 and KOOS, JR was found (r = 0.72, P < .001) making the KOOS, JR a valid external anchor. The threshold score of the FJS-12 which maximized the sensitivity and specificity for detecting a PASS was 33.3 (AUC = 0.78, 95% CI [0.74, 0.83]). The cut-off value computed with the 75^th percentile approach was 77.1 (95% CI [73.9, 81.5]).

CONCLUSION

The PASS threshold for the FJS-12 was 33.3 and 77.1 at 1-year follow-up after primary TKA using the receiver operating characteristic (ROC) curve and 75^th percentile approaches, respectively. These values can be used to assess the successful achievement of a forgotten joint.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Tourniquet use in total knee arthroplasty and the risk of infection: a meta-analysis of randomised controlled trials

Purpose

The intra-operative use of tourniquets during Total Knee Arthroplasty (TKA) is common practice. The advantages of tourniquet use include decreased operating time and the creation of a bloodless visualisation field. However, tourniquet use has recently been linked with increased post-operative pain, reduced range of motion, and slower functional recovery. Importantly, there is limited evidence of the effect of tourniquet use on infection risk. The purpose of this systematic review and meta-analysis is to fill this gap in the literature by synthesising data pertaining to the association between tourniquet use and infection risk in TKA.

Methods

A systematic literature search was performed on Pubmed, Embase, Cochrane and clinicaltrials.gov up to May 2021. Randomized control trials were included, comparing TKA outcomes with and without tourniquet use. The primary outcome was overall infection rate. Secondary outcomes included superficial and deep infection, skin necrosis, skin blistering, DVT rate, and transfusion rate.

Results

14 RCTs with 1329 patients were included. The pooled incidence of infection in the tourniquet group (4.0%, 95% CI = 2.7–5.4) was significantly higher compared to the non-tourniquet group (2.0%, 95% CI = 1.1–3.1) with an OR of 1.9 (95% CI = 1.1–3.76, p = 0.03). The length of hospital stay, haemoglobin drop (0.33 95% CI =0.12–0.54), P = 0.002) and transfusion rates (OR of 2.7, 95%CI = 1.4–5.3, P = < 0.01) were higher in the tourniquet group than the non-tourniquet group. The difference in the length of inhospital stay was 0.24 days favouring the non-tourniquet group (95% CI = 0.10–0.38, P = < 0.01). The incidence of skin blistering (OR 2.6, 95% CI = 0.7–9.9, p = 0.17), skin necrosis (OR 3.0, 95% CI = 0.50–19.3, p = 0.25), and DVT rates (OR 1.5, 95% CI = 0.60–3.60, p = 0.36) did not differ between the two groups.

Conclusion

Quantitative synthesis of the data suggested tourniquet use was associated with an increased overall risk of infection, intraoperative blood loss, need for blood transfusion and longer hospital stay. Findings of this meta-analysis do not support the routine use of tourniquet in TKA and arthroplasty surgeons should consider any potential additional risks associated with its use.

Level of evidence

meta-analysis, Level II.

Health economic value of CT scan based robotic assisted UKA: a systematic review of comparative studies

PURPOSE

The aim of this systematic review was to compare relevant health economic consequences of the CT-based robotic-arm-assisted system versus conventional Uni-compartmental Knee Arthroplasty (UKA).

METHODS

In November 2020, A PRISMA systematic review was conducted using four databases (Pubmed, Scopus, Cochrane and Google Scholar) to identify all comparative studies reporting health economic assessments, such as robotic system costs, consumable costs, surgical revision rate, operating time, length of stay, and inpatient care costs.

RESULTS

A total of nine comparative studies published between 2014 and 2020 were included in this systematic review. There was a moderate risk of bias as assessed using the ROBINS-I Tool. The CT-based robotic-arm-assisted system seemed to be associated with a lower risk of revision, decreased analgesia requirements during hospitalization, a shorter length of stay, and lower inpatient care costs compared to a conventional technique.

CONCLUSION

CT-based robotic-arm-assisted system for UKA appears to be an economically viable solution with a positive health economic impact as it tends to decrease revision rate compared to conventional UKA, improve post-operative rehabilitation and analgesia management. Post-operative inpatient care costs seem lower with the robotic-assisted system but depend on institutional case volume and differ among health systems. More studies are needed to confirm cost-effectiveness of CT-based robotic-arm-assisted system based on different health systems.

LEVEL OF EVIDENCE

Systematic review, Level IV.

Bi-unicondylar arthroplasty : a biomechanics and clinical outcomes study

AIMS

Bi-unicondylar arthroplasty (Bi-UKA) is a bone and anterior cruciate ligament (ACL)-preserving alternative to total knee arthroplasty (TKA) when the patellofemoral joint is preserved. The aim of this study is to investigate the clinical outcomes and biomechanics of Bi-UKA.

METHODS

Bi-UKA subjects (n = 22) were measured on an instrumented treadmill, using standard gait metrics, at top walking speeds. Age-, sex-, and BMI-matched healthy (n = 24) and primary TKA (n = 22) subjects formed control groups. TKA subjects with preoperative patellofemoral or tricompartmental arthritis or ACL dysfunction were excluded. The Oxford Knee Score (OKS) and EuroQol five-dimension questionnaire (EQ-5D) were compared. Bi-UKA, then TKA, were performed on eight fresh frozen cadaveric knees, to investigate knee extensor efficiency under controlled laboratory conditions, using a repeated measures study design.

RESULTS

Bi-UKA walked 20% faster than TKA (Bi-UKA mean top walking speed 6.7 km/h (SD 0.9),TKA 5.6 km/h (SD 0.7), p < 0.001), exhibiting nearer-normal vertical ground reaction forces in maximum weight acceptance and mid-stance, with longer step and stride lengths compared to TKA (p < 0.048). Bi-UKA subjects reported higher OKS (p = 0.004) and EQ-5D (p < 0.001). In vitro, Bi-UKA generated the same extensor moment as native knees at low flexion angles, while reduced extensor moment was measured following TKA (p < 0.003). Conversely, at higher flexion angles, the extensor moment of TKA was normal. Over the full range, the extensor mechanism was more efficient following Bi-UKA than TKA (p < 0.028).

CONCLUSION

Bi-UKA had more normal gait characteristics and improved patient-reported outcomes, compared to matched TKA subjects. This can, in part, be explained by differences in extensor efficiency. Cite this article: Bone Joint Res 2021;10(11):723-733.

Joint awareness after unicompartmental knee arthroplasty and total knee arthroplasty: a systematic review and meta-analysis of cohort studies

PURPOSE

The purpose of this systematic review and meta-analysis is to evaluate the joint awareness after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). It was hypothesized that patients with UKA could better forget about their artificial joint in comparison to TKA.

METHODS

A search of major literature databases and bibliographic details revealed 105 studies evaluating forgotten joint score in UKA and TKA. Seven studies found eligible for this review were assessed for risk of bias and quality of evidence using the Newcastle-Ottawa Scale. The forgotten joint score (FJS-12) was assessed at 6 months, 1 year, and 2 years.

RESULTS

The mean FJS-12 at 2 years was 82.35 in the UKA group and 74.05 in the TKA group. Forest plot analysis of five studies (n = 930 patients) revealed a mean difference of 7.65 (95% CI: 3.72, 11.57, p = 0.0001; I² = 89% with p < 0.0001) in FJS-12 at 2 years. Further sensitivity analysis lowered I² heterogeneity to 31% after exclusion of the study by Blevin et al. (MD 5.88, 95%CI: 3.10, 8.66, p < 0.0001). A similar trend of differences in FJS-12 between the groups was observed at 6 months (MD 32.49, 95% CI: 17.55, 47.43, p < 0.0001) and at 1 year (MD 25.62, 95% CI: 4.26, 46.98, p = 0.02).

CONCLUSIONS

UKA patients can better forget about their artificial joint compared to TKA patients.

LEVEL OF EVIDENCE

III.

Robotic-arm assisted THA can achieve precise cup positioning in developmental dysplasia of the hip : a case control study

AIMS

This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH).

METHODS

The study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured.

RESULTS

The mean values of absolute differences (postoperative CT-preoperative plan) were 1.7° (standard deviation (SD) 2.0) (inclination) and 2.5° (SD 2.1°) (anteversion) in DDH patients, and no significant differences were found between non-DDH and DDH patients. The mean absolute differences for 3D cup position were 1.1 mm (SD 1.0) (coronal plane) and 1.2 mm (SD 2.1) (axial plane) in DDH patients, and no significant differences were found between two groups. No significant difference was found either in cup alignment between postoperative CT and navigation record after cup screws or in the severity of DDH. Excellent restoration of leg length and combined offset were achieved in both groups.

CONCLUSION

We demonstrated that robotic-assisted THA may achieve precise cup positioning in DDH patients, and may be useful in those with severe DDH. Cite this article: Bone Joint Res 2021;10(10):629-638.

No difference in functional outcomes, quality of life and survivorship between metal-backed and all-polyethylene tibial components in unicompartmental knee arthroplasty: a 10-year follow-up study

PURPOSE

The purpose of this study was to compare functional outcomes, quality of life and survivorship at a minimum of 10 years postoperatively, between MB and AP tibial components in fixed-bearing UKAs.

METHODS

A retrospective cohort study of 146 Query ID="Q3" Text="Author names: Please confirm if the author names are presented accurately and in the correct sequence (Lo Ngai Nung, Yeo Seng Jin). Also, kindly confirm the details in the metadata are correct." UKAs performed between 2004 and 2007 by a single fellowship-trained arthroplasty surgeon was carried out. 27 UKAs received MB tibial components and 119 UKAs received AP tibial components. The cohort was followed up prospectively for 10 years. Functional outcomes were compared using the Knee Society Functional Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS). Quality of life measures were obtained from the Physical Component Summary (PCS) and Mental Component Summary (MCS), derived from the Short Form 36 Health Survey (SF-36). Propensity score matching was performed in a 1:3 ratio of MB versus AP tibial components to account for possible confounding variables. Thereafter, outcomes between the two groups were compared. The proportion of patients who had attained the minimum clinically important difference (MCID) for the abovementioned scores was recorded as well.

RESULTS

After propensity score matching, there were 28 UKAs with MB tibial components and 76 UKAs with AP tibial components. There was no significant difference between the two groups in functional outcomes (KSFS, KSKS and OKS), quality of life (PCS and MCS) and survivorship (92.3% vs 91.1%, respectively) at a minimum of 10 years postoperatively. However, a significantly higher proportion of patients in the group with AP tibial components attained the MCID for PCS at 10 years postoperatively, compared to those with MB tibial components (p = 0.031).

CONCLUSION

In conclusion, there were no significant differences in functional outcomes measures, quality of life and survivorship between MP and AP tibial components at a minimum of 10 years postoperatively.

LEVEL OF EVIDENCE

III.

Robotic arm-assisted versus conventional medial unicompartmental knee arthroplasty: five-year clinical outcomes of a randomized controlled trial

Aims

Unicompartmental knee arthroplasty (UKA) is a bone-preserving treatment option for osteoarthritis localized to a single compartment in the knee. The success of the procedure is sensitive to patient selection and alignment errors. Robotic arm-assisted UKA provides technological assistance to intraoperative bony resection accuracy, which is thought to improve ligament balancing. This paper presents the five-year outcomes of a comparison between manual and robotically assisted UKAs.

Methods

The trial design was a prospective, randomized, parallel, single-centre study comparing surgical alignment in patients undergoing UKA for the treatment of medial compartment osteoarthritis (ISRCTN77119437). Participants underwent surgery using either robotic arm-assisted surgery or conventional manual instrumentation. The primary outcome measure (surgical accuracy) has previously been reported, and, along with secondary outcomes, were collected at one-, two-, and five-year timepoints. Analysis of five-year results and longitudinal analysis for all timepoints was performed to compare the two groups.

Results

Overall, 104 (80%) patients of the original 130 who received surgery were available at five years (55 robotic, 49 manual). Both procedures reported successful results over all outcomes. At five years, there were no statistical differences between the groups in any of the patient reported or clinical outcomes. There was a lower reintervention rate in the robotic arm-assisted group with 0% requiring further surgery compared with six (9%) of the manual group requiring additional surgical intervention (p < 0.001).

Conclusion

This study has shown excellent clinical outcomes in both groups with no statistical or clinical differences in the patient-reported outcome measures. The notable difference was the lower reintervention rate at five years for roboticarm-assisted UKA when compared with a manual approach.

Cite this article: Bone Joint J 2021;103-B(6):1088–1095.

The effect of COVID-19 restrictions on rehabilitation and functional outcome following total hip and knee arthroplasty during the first wave of the pandemic

AIMS

The primary aim was to assess the patient-perceived effect of restrictions imposed due to COVID-19 on rehabilitation following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Secondary aims were to assess perceived restrictions, influence on mental health, and functional outcome compared to patients undergoing surgery without restriction.

METHODS

During February and March 2020, 105 patients underwent THA (n = 48) or TKA (n = 57) and completed preoperative and six-month postoperative assessments. A cohort of 415 patients undergoing surgery in 2019 were used as the control. Patient demographic data, BMI, comorbidities, Oxford Hip Score (OHS) or Knee Score (OKS), and EuroQoL five-domain (EQ-5D) score were collected preoperatively and at six months postoperatively. At six months postoperatively, the 2020 patients were also asked to complete a questionnaire relating to the effect of the social restrictions on their outcome and their mental health.

RESULTS

Nearly half of the patients (47.6%, n = 50/105) felt that the restrictions imposed by COVID-19 had limited their rehabilitation and were associated with a significantly worse postoperative OKS (p < 0.001), EQ-5D score (p < 0.001), and lower satisfaction rate (p = 0.019). The reasons for the perceived limited rehabilitation were: being unable to exercise (n = 32, 64%), limited access to physiotherapy (n = 30, 60%), and no face-to-face follow-up (n = 30, 60%). A quarter (n = 26) felt that their mental health had deteriorated postoperatively; 17.1% (n = 18) felt depressed and 26.7% (n = 28) felt anxious. Joint-specific scores and satisfaction for the 2020 group were no different to the 2019 group, however patients undergoing THA in 2020 had a significantly worse postoperative EQ-5D compared to the 2019 cohort (difference 0.106; p = 0.001) which was not observed in patients undergoing TKA.

CONCLUSION

Half of the 2020 cohort felt that their rehabilitation had been limited and was associated with worse postoperative Oxford and EQ-5D scores, and lower rates of patient satisfaction, but relative to the 2019 cohort their overall outcomes were no different, with the exception of THA patients who had a worse general health score. Level of evidence: Prospective study, Level 2 Cite this article: Bone Jt Open 2021;2(6):380-387.

Meaningful values in the Forgotten Joint Score after total knee arthroplasty

AIMS

The aim of this study was to identify the minimal clinically important difference (MCID), minimal important change (MIC), minimal detectable change (MDC), and patient-acceptable symptom state (PASS) threshold in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total knee arthroplasty (TKA).

METHODS

During a one-year period 484 patients underwent a primary TKA and completed preoperative and six-month FJS and OKS. At six months patients were asked, "How satisfied are you with your operated knee?" Their response was recorded as: very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied. The difference between patients recording neutral (n = 44) and satisfied (n = 153) was used to define the MCID. MIC for a cohort was defined as the change in the FJS for those patients declaring their outcome as satisfied, whereas receiver operating characteristic curve analysis was used to determine the MIC for an individual and the PASS threshold. Distribution-based methodology was used to calculate the MDC.

RESULTS

Using satisfaction as the anchor question, the MCID for the FJS was 16.6 (95% confidence interval (CIs) 8.9 to 24.3; p < 0.001) and when adjusting for confounding this decreased to 13.7 points (95% CI 4.8 to 22.5; p < 0.001). The MIC for the FJS for a cohort of patients was 17.7 points and for an individual patient was 10 points. The MDC90 for the FGS was 12 points; where 90% of patients scoring more than this will have experienced a real change that is beyond measurement error. The PASS was defined as 22 points or more in the postoperative FJS.

CONCLUSION

The estimates for MCID and MIC can be used to assess whether there is clinical difference between two groups and whether a cohort/patient has had a meaningful change in their FJS, respectively. The MDC90 of 12 points suggests a value lower than this may fall within measurement error. A postoperative FJS of 22 or more was predictive of achieving PASS. Cite this article: Bone Joint J 2021;103-B(5):846-854.

Improved sizing with image-based robotic-assisted system compared to image-free and conventional techniques in medial unicompartmental knee arthroplasty

AIMS

Ideal component sizing may be difficult to achieve in unicompartmental knee arthroplasty (UKA). Anatomical variants, incremental implant size, and a reduced surgical exposure may lead to over- or under-sizing of the components. The purpose of this study was to compare the accuracy of UKA sizing with robotic-assisted techniques versus a conventional surgical technique.

METHODS

Three groups of 93 medial UKAs were assessed. The first group was performed by a conventional technique, the second group with an image-free robotic-assisted system (Image-Free group), and the last group with an image-based robotic arm-assisted system, using a preoperative CT scan (Image-Based group). There were no demographic differences between groups. We compared six parameters on postoperative radiographs to assess UKA sizing. Incorrect sizing was defined by an over- or under-sizing greater than 3 mm.

RESULTS

There was a higher rate of tibial under-sizing posteriorly in the conventional group compared to robotic-assisted groups (47.3% (n = 44) in conventional group, 29% (n = 27) in Image-Free group, 6.5% (n = 6) in Image-Based group; p < 0.001), as well as a higher rate of femoral under-sizing posteriorly (30.1% (n = 28) in conventional group, 7.5% (n = 7) in Image-Free group, 12.9% (n = 12) in Image-Based group; p < 0.001). The posterior femoral offset was more often increased in the conventional group, especially in comparison to the Image-Based group (43% (n = 40) in conventional group, 30.1% (n = 28) in Image-Free group, 8.6% (n = 8) in Image-Based group; p < 0.001). There was no significant overhang of the femoral or tibial implant in any groups.

CONCLUSION

Robotic-assisted surgical techniques for medial UKA decrease the risk of tibial and femoral under-sizing, particularly with an image-based system using a preoperative CT scan. Cite this article: Bone Joint J 2021;103-B(4):610-618.

Validation of joint space narrowing on plain radiographs and its relevance to partial knee arthroplasty

AIMS

To explore the clinical relevance of joint space width (JSW) narrowing on standardized-flexion (SF) radiographs in the assessment of cartilage degeneration in specific subregions seen on MRI sequences in knee osteoarthritis (OA) with neutral, valgus, and varus alignments, and potential planning of partial knee arthroplasty.

METHODS

We retrospectively reviewed 639 subjects, aged 45 to 79 years, in the Osteoarthritis Initiative (OAI) study, who had symptomatic knees with Kellgren and Lawrence grade 2 to 4. Knees were categorized as neutral, valgus, and varus knees by measuring hip-knee-angles on hip-knee-ankle radiographs. Femorotibial JSW was measured on posteroanterior SF radiographs using a special software. The femorotibial compartment was divided into 16 subregions, and MR-tomographic measurements of cartilage volume, thickness, and subchondral bone area were documented. Linear regression with adjustment for age, sex, body mass index, and Kellgren and Lawrence grade was used.

RESULTS

We studied 345 neutral, 87 valgus, and 207 varus knees. Radiological JSW narrowing was significantly (p < 0.01) associated with cartilage volume and thickness in medial femorotibial compartment in neutral (r = 0.78, odds ratio (OR) 2.33) and varus knees (r = 0.86, OR 1.92), and in lateral tibial subregions in valgus knees (r = 0.87, OR 3.71). A significant negative correlation was found between JSW narrowing and area of subchondral bone in external lateral tibial subregion in valgus knees (r = -0.65, p < 0.01) and in external medial tibial subregion in varus knees (r = -0.77, p < 0.01). No statistically significant correlation was found in anterior and posterior subregions.

CONCLUSION

SF radiographs can be potentially used for initial detection of cartilage degeneration as assessed by MRI in medial and lateral but not in anterior or posterior subregions. Cite this article: Bone Joint Res 2021;10(3):173-187.

Elective orthopaedic cancellations due to the COVID-19 pandemic: where are we now, and where are we heading?

AIMS

The primary aim is to estimate the current and potential number of patients on NHS England orthopaedic elective waiting lists by November 2020. The secondary aims are to model recovery strategies; review the deficit of hip and knee arthroplasty from National Joint Registry (NJR) data; and assess the cost of returning to pre-COVID-19 waiting list numbers.

METHODS

A model of referral, waiting list, and eventual surgery was created and calibrated using historical data from NHS England (April 2017 to March 2020) and was used to investigate the possible consequences of unmet demand resulting from fewer patients entering the treatment pathway and recovery strategies. NJR data were used to estimate the deficit of hip and knee arthroplasty by August 2020 and NHS tariff costs were used to calculate the financial burden.

RESULTS

By November 2020, the elective waiting list in England is predicted to be between 885,286 and 1,028,733. If reduced hospital capacity is factored into the model, returning to full capacity by November, the waiting list could be as large as 1.4 million. With a 30% increase in productivity, it would take 20 months if there was no hidden burden of unreferred patients, and 48 months if there was a hidden burden, to return to pre-COVID-19 waiting list numbers. By August 2020, the estimated deficits of hip and knee arthroplasties from NJR data were 18,298 (44.8%) and 16,567 (38.6%), respectively, compared to the same time period in 2019. The cost to clear this black log would be £198,811,335.

CONCLUSION

There will be up to 1.4 million patients on elective orthopaedic waiting lists in England by November 2020, approximate three-times the pre-COVID-19 average. There are various strategies for recovery to return to pre-COVID-19 waiting list numbers reliant on increasing capacity, but these have substantial cost implications. Cite this article: Bone Jt Open 2021;2(2):103-110.

Unicondylar knee replacement versus total knee replacement for the treatment of medial knee osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Since the optimal surgery for isolated medial knee osteoarthritis (OA) is unclear, this study aimed at comparing the effectiveness of unicondylar knee replacement (UKR) with total knee replacement (TKR) for simple medial knee OA.

METHODS

Literature searches of PubMed, Embase, Web of Science, and the Cochrane Library were searched up to 1th April 2020. Only studies comparing UKR with TKR for isolated medial knee OA were included. Data collection and extraction, quality assessment, and data analyses were performed according to the Cochrane standards.

RESULTS

A total of 13 articles with 1888 patients were included, among which, 944 and 944 underwent UKR and TKR, respectively. The analyzed postoperative outcomes were mostly within 5 years of follow-up. The meta-analysis showed that UKR improved knee general function (P < 0.00001) and health (P = 0.02), moreover, reduced post-operative pain (P = 0.01) and complications (P < 0.05) more than TKR. There were no significant differences in postoperative revision (P = 0.252), high-activity arthroplasty score (HAAS) (P = 0.307) and Oxford knee score (OKS) (P = 0.15) between the two techniques.

CONCLUSIONS

The patients of UKR could achieve better clinical results than that of TKR, moreover, there were negligible differences between the two techniques in postoperative revision in the early and mid-term follow-up and surgeons should be aware of the important reasons for revision of UKR. Thus, UKR instead of TKR should be performed in patients with late-stage isolated medial knee OA.

The preoperative Oxford Knee Score is an independent predictor of achieving a postoperative ceiling score after total knee arthroplasty

Aims

The primary aim of this study was to assess whether the postoperative Oxford Knee Score (OKS) demonstrated a ceiling effect at one and/or two years after total knee arthroplasty (TKA). The secondary aim was to identify preoperative independent predictors for patients that achieved a ceiling score after TKA.

Methods

A retrospective cohort of 5,857 patients undergoing a primary TKA were identified from an established arthroplasty database. Patient demographics, body mass index (BMI), OKS, and EuroQoL five-dimension (EQ-5D) general health scores were collected preoperatively and at one and two years postoperatively. Logistic regression analysis was used to identify independent preoperative predictors of patients achieving postoperative ceiling scores. Receiver operating characteristic curve was used to identify a preoperative OKS that predicted a postoperative ceiling score.

Results

The ceiling effect was 4.6% (n = 272) at one year which increased significantly (odds ratio (OR) 40.3, 95% confidence interval (CI) 30.4 to 53.3; p < 0.001) to 6.2% (n = 363) at two years, when defined as those with a maximal score of 48 points. However, when the ceiling effect was defined as an OKS of 44 points or more, this increased to 26.3% (n = 1,540) at one year and further to 29.8% (n = 1,748) at two years (OR 21.6, 95% CI 18.7 to 25.1; p < 0.001). A preoperative OKS of 23 or more and 22 or more were predictive of achieving a postoperative ceiling OKS at one and two years when defined as a maximal score or a score of 44 or more, respectively.

Conclusion

The postoperative OKS demonstrated a small ceiling effect when defined by a maximal score, but when defined by a postoperative OKS of 44 or more the ceiling effect was moderate and failed to meet standards. The preoperative OKS was an independent predictor of achieving a ceiling score. Cite this article: Bone Joint J 2020;102-B(11):1519–1526.