Early complications of total hip and knee replacement: a comparison of outcomes in a regional orthopaedic hospital and two independent treatment centres

Modified Frailty Index as a Predictor of Adverse Outcomes in Elective Primary Hip and Knee Replacement Surgery Patients at a Tertiary Care Hospital in Pakistan: A Cross-Sectional Study

Objective The objective was to evaluate the modified frailty index as a predictor of early (within 30 days) postoperative complications in total joint arthroplasty patients, in a low middle-income country. Material and methods A cross-sectional study was carried out which included patients with ages ranging from 23 to 86 years, who underwent elective primary Total Hip or Knee Arthroplasties (TKA or THA) between December 2021 and February 2023. Modified frailty index (mFI-5) was calculated and 30-day morbidity and mortality were recorded. Post-operative complications were categorized as either surgical or medical and recorded. Results A total of 175 patients were included, amongst whom the majority were females (68.6%, n=120) and the mean age was 60.5 ± 13.2 years. 85 patients (48.6%) had a mFI-5 score of one while 48 patients (27.4%) had a score of two. Superficial surgical site infection was the most common complication overall in 6 patients (3.4%); however, no case of prosthetic joint infection was noted. Deep vein thrombosis (DVT) was the most common medical complication (1.7%, n=3). 5 patients (2.9%) required re-admission and two mortalities were recorded within the 30-day interval. A significant association was noted between post-operative surgical complications and mFI-5 score (p-value = < 0.001), with the risk of complications increasing with a higher mFI-5 score. Smoking was noted to be a risk factor for post-operative medical complications as well as 30-day mortality. Conclusion The current study shows that the mFI-5 index can effectively be used as a predictor of postoperative complications in the South Asian region such as Pakistan. This should be calculated routinely and can be used as a tool for pre-operative assessment and counseling.

Cost-Effectiveness Analysis of a Medial Meniscus Replacement Prosthesis for the Treatment of Patients with Medial Compartment Pain in the United Kingdom

BACKGROUND

The most common intra-articular knee injury is a meniscal tear, which commonly occurs secondary to trauma following twisting or hyperflexion. Treatment options for meniscal tears can either be surgical or non-surgical, and range from rest, exercise, bracing and physical therapy to surgical intervention, including meniscal repair and partial meniscectomy. In patients with persistent pain following loss of meniscus tissue, treatment can include partial replacement or meniscal allograft transplantation. The NUsurface^® prosthesis has been developed as a treatment option for patients experiencing persistent knee pain post medial meniscus (MM) surgery.

OBJECTIVE

The aim of this study was to assess the cost effectiveness of MM replacement using NUsurface for the treatment of patients with medial compartment pain following previous partial medial meniscectomy, from a UK health service perspective.

METHODS

An economic decision-analytic model was developed to assess the cost per quality-adjusted life-year (QALY) gained associated with the introduction of MM replacement using NUsurface compared with non-surgical standard of care, over a lifetime time horizon. The model structure was primarily informed by a previous clinical trial (VENUS) and was developed based on the clinical pathways typically followed by patients with this condition, with treatment pathways and probabilities of clinical progression adjusted depending on whether patients were receiving the intervention or undergoing current practice. A hypothetical cohort of adult patients (mean age of 50 years) was modelled, with clinical data sourced from the VENUS study as well as relevant UK literature. Both deterministic and probabilistic sensitivity analyses were carried out to explore uncertainty in the model results.

RESULTS

The base-case probabilistic results indicate that MM replacement using NUsurface is likely to be cost effective across a range of willingness-to-pay (WTP) thresholds (95% probability of being cost effective at the National Institute for Health and Care Excellence (NICE)-recommended £20,000 WTP threshold). Although per-patient costs increase, QALYs are also gained, with the incremental cost per QALY (probabilistic value = £5011) being below £20,000. Deterministic sensitivity analyses indicate that the parameters that have the greatest impact on results are the failure rate in the control group (current practice), utility scores, and the cost of undergoing MM replacement using NUsurface.

CONCLUSIONS

Based on the analysis presented, MM replacement with the NUsurface prosthetic implant is likely to be a cost-effective use of UK health care service resources compared with current standard care.

Results of Reduction of Dislocated Prosthetic Hips in the Emergency Department

BACKGROUND

Dislocation of total hip arthroplasty (dTHA) is a commonly encountered complication in the emergency department (ED). Several studies have been conducted that describe the overall success rate after reduction in the ED, however, all were small in sample size.

OBJECTIVES

The aim of the study was to assess the success rate of reduction of dTHA by emergency physicians in the ED under procedural sedation (PSA).

METHODS

Patients who presented to the ED with a dislocated prosthetic hip were eligible for inclusion. We performed a retrospective cohort study assessing success rate. Secondary parameters included time to reduction, discharge rate from the ED, and complication rate.

RESULTS

There were 305 patients analyzed. Of these, 31 were excluded due to hemi-arthroplasty and 25 because they went primarily for reduction in the operating room. In total, 249 patients were included. Of 249 attempted reductions in the ED, 230 (92%, 95% confidence interval [CI] 89-96%) were successful. Seventy-one cases (28.5%, 95% CI 22.9-34.2%) were discharged from the ED after successful reduction. Six cases (2.4%, 95% CI 0.2-2.6%) experienced complications related to PSA and three cases (1.2%, 95% CI 0.5-4.3%) experienced complications related to reduction.

CONCLUSION

Reduction of a dTHA can be performed safely in the ED under PSA by emergency physicians with a high rate of success.

The relationship between alignment, function and loading in total knee replacement: In-vivo analysis of a unique patient population

The purpose of this study was to quantify the effect of total knee replacement (TKR) alignment on in-vivo knee function and loading in a unique patient cohort who have been identified as having a high rate of component mal-alignment. Post-TKR (82.4 ± 6.7 months), gait analysis was performed on 25 patients (27 knees), to calculate knee kinematics and kinetics. For a step activity, video fluoroscopic analysis quantified in-vivo implant kinematics. Frontal plane lower-limb alignment was defined by the Hip-Knee-Ankle angle (HKA) measured on long leg static X-rays. Transverse plane component rotation was calculated from computed tomography scans. Sagittal plane alignment was defined by measuring the flexion angle of the femoral component and the posterior tibial slope angle (PTSA). For gait analysis, a more varus HKA correlated with increased peak and dynamic joint kinetics, predicting 47.6% of Knee Adduction Angular Impulse variance. For the step activity, during step-up and single leg loaded, higher PTSA correlated with a posterior shift in medial compartment Anterior-Posterior (AP) translation. During step-down, higher PTSA correlated with reduced lateral compartment AP translation with a posterior shift in AP translation in both compartments. A more varus HKA correlated with a more posterior medial AP translation and inter-component rotation was related to transverse plan range of motion. This in-vivo study found that frontal plane lower-limb alignment had a significant effect on joint forces during gait but had minimal influence on in-vivo implant kinematics for step activity. PTSA was found to influence in-vivo TKR translations and is therefore an important surgical factor.

No Difference in 5-year Clinical or Radiographic Outcomes Between Kinematic and Mechanical Alignment in TKA: A Randomized Controlled Trial

BACKGROUND

In kinematic alignment in TKA, the aim is to match the implant's position to the pre-arthritic anatomy of an individual patient, in contrast to the traditional goal of neutral mechanical alignment. However, there are limited mid-term, comparative data for survivorship and functional outcomes for these two techniques.

QUESTIONS/PURPOSES

In the setting of a randomized, controlled trial at 5 years, is there a difference between kinematic alignment and mechanical alignment in TKA in terms of (1) patient-reported outcome measures, (2) survivorship free from revision or reoperation, and (3) the incidence of radiographic aseptic loosening?

METHODS

In the initial study, 99 primary TKAs for osteoarthritis were randomized to either the mechanical alignment (n = 50) or kinematic alignment (n = 49) group. Computer navigation was used in the mechanical alignment group, and patient-specific cutting blocks were used in the kinematic alignment group. At 5 years, 95% (48 of 50) of mechanical alignment and 96% (47 of 49) of kinematic alignment TKAs were available for follow-up. Knee function was assessed using the Knee Society Score (KSS), VAS, Oxford Knee Score (OKS), WOMAC, Forgotten Joint Score (FJS) and EuroQol 5D. Survivorship free from reoperation (any reason) and revision (change or addition of any component) was determined via Kaplan-Meier analysis. Radiographs were assessed for signs of aseptic loosening (as defined by the presence of progressive radiolucent lines in two or more zones) by a single blinded observer.

RESULTS

At 5 years, there were no differences in any patient-reported outcome measure between the two groups. For example, the mean OKS did not differ between the two groups (kinematic alignment: 41.4 ± 7.2 versus mechanical alignment: 41.7 ± 6.3; difference -0.3 [95% confidence interval - 3.2 to 2.5]; p = 0.99). At 5 years, survivorship free from reoperation was 92.2 (95% CI 80.4 to 97.0) for mechanical alignment and 89.7 (95% CI 77.0 to 95.6) for kinematic alignment (log rank test; p = 0.674), survivorship free from revision was 94.1 (95% CI 82.9 to 98.1) for mechanical alignment and 95.9 (95% CI 84.5 to 99.0) for kinematic alignment (log rank test; p = 0.681). At 5 years, one patient demonstrated radiographic aseptic loosening for the mechanical alignment group; no cases were identified for the kinematic alignment group.

CONCLUSIONS

We found no mid-term functional or radiographic differences between TKAs with mechanical alignment or kinematic alignment. The anticipated improvements in patient-reported outcomes with kinematic alignment were not realized. Because kinematic alignment results in a high proportion of patients whose tibial components are inserted in varus, loosening remains a potential long-term concern. Given the unknown impact on long-term survivorship of the substantial alignment alterations with kinematic alignment, our findings do not support the routine use of kinematic alignment outside of a research setting.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Preparing the femur before the acetabulum does not reduce total blood loss in primary total hip replacement

Introduction

Total hip replacement is a common and effective surgical intervention for patients with debilitating joint pain but it does represent a significant surgical intervention. For such interventions, blood loss is a potential cause of morbidity and mortality. Optimisation of surgical interventions focuses on reducing such risks. The aim of this study was to determine whether the order of surgical steps, preparing the femur before or after the acetabulum, was associated with the amount of total blood loss in total hip replacement.

Methods

We performed a retrospective study of 100 patients undergoing primary total hip replacement between 2014 and 2018. This was a before and after (interrupted time series) study around the introduction of femur first preparation for total hip replacement in our unit. Fifty patients underwent a standard femoral preparation after placement of the acetabular component. The second 50 patients had the femoral canal prepared and broached prior to the acetabular component. Estimated blood volume and total blood loss associated with the perioperative period were calculated for each patient and a multiple regression analysis performed to account for other patient and surgical variables associated with perioperative blood loss.

Results

There was a small reduction in total blood loss for the group who underwent femoral preparation prior to acetabular preparation with a mean difference of 39 mls. This difference however was not clinically or statistically (p = 0.392) significant. Gender (p < 0.0001), Body Mass Index (BMI; p < 0.0001), preoperative haematocrit (p < 0.0001), postoperative haematocrit (p < 0.0001) and age (p = 0.004) were the only factors significantly associated with the total volume of blood loss.

Conclusions

Whether the femur was prepared before or after the acetabulum did not significantly predict the total volume of blood loss for primary total hip replacement.

Effect of an independent-sector treatment centre on provision of elective orthopaedic surgery in east and north Hertfordshire

Introduction Independent Sector Treatment Centres (ISTCs) were created to relieve pressure from Acute Hospital Trusts. In October 2011, an ISTC opened on the grounds of a hospital within the East and North Hertfordshire NHS Trust. Most elective orthopaedic procedures were transferred there. We investigated the effect on productivity of operating theatres working in the ISTC compared with those working in the Acute Hospital Trust (AHT). Methods A 3-month period of working at the AHT was compared with the same period 9-months later in the ISTC, which were termed 'pre-' and 'post-ISTC' opening, respectively. Data for upper limb (UL) as well as foot and ankle (F&A) surgery were collected. Differences in the number of lists and patients per list constituted usage analyses. Financial productivity was calculated from the latest Payment by Results (PbR) data. A two-tailed Mann-Whitney U-test at a confidence level of 95% was employed to compare costs between groups. Results The UL surgeon undertook 18 lists in both years with 66 patients (pre-ISTC) and 32 (post-ISTC), eliciting a reduction in productivity of 51.5%. There were 13 lists for F&A surgery pre-ISTC with 67 procedures, and 20 lists with 49 patients post-ISTC. Allowing for the difference in the number of lists, a reduction of 52.5% was noted. PbR analyses confirmed productivity of £169,695 (pre-ISTC) and £95,760 (post-ISTC) at a loss of £73,935 for the UL surgeon. F&A data revealed £97,801 (pre-ISTC) and £91,960 (post-ISTC) at a loss of £54,742 when correcting for the difference in the number of lists. There was a combined reduction in potential financial productivity of £128,677 over 3 months or £514,708 over 1 year. Discussion Implementation of the ISTC was detrimental to departmental efficiency, with <50% of the number of patients being treated and a marked reduction in financial productivity.

Factors influencing the outcome of deep infection following total knee arthroplasty

BACKGROUND

Whereas clinical studies have revealed a number of important risk factors for postoperative infection following total knee arthroplasty (TKA), it is unclear which factor influences clinical results. A multicenter study was therefore performed by reviewing 51 patients with deep infection after TKA and seeking for the factors related to clinical outcomes.

METHODS

Fifty-one deep infections after TKA were treated from 2000 to 2011 at the multicenter including a university or three arthroplasty centers. Among them, two clinical outcome measures including retention of prosthesis at initial treatment and functional prosthetic knee were assessed for several factors such as age, sex, primary diagnosis, onset time after primary TKA, type of hospital where the primary TKA was performed and the organism's resistance to methicillin using the logistic regression analysis model.

RESULTS

Among the factors, type of hospital where the primary TKA was performed and onset time after primary TKA had higher multivariable-adjusted odds ratios (ORs) for retention of primary prosthesis (ORs 35.21 and 11.69, respectively.). The cases which primary surgery were performed in arthroplasty centers had higher multivariable-adjusted ORs for functional prosthetic knee (OR 4.9). Thirty-one infection cases with non-methicillin-resistant organisms were all able to keep functional prosthetic knee after the operation, whereas 13 out of 20 infection cases with methicillin-resistant organisms lost their knee function after the operation.

CONCLUSIONS

Onset time after primary TKA, type of hospital where the primary surgery was performed and the organism's resistance to methicillin are important factors influencing the clinical outcomes after infected TKA.

LEVEL OF EVIDENCE

Level 3. Retrospective comparative study.

Total joint arthroplasty readmission rates and reasons for 30-day hospital readmission

Given institutional pressures to reduce hospital length of stay (LOS) we hypothesized that "failure to cope" would be a significant factor for readmission following total joint arthroplasty (TJA). A retrospective review of 4288 TJA patients was conducted to determine readmission rates and reasons for readmit within 30 days of discharge. Ninety-five patients (2.2%; 95% CI: 1.8%-2.7%) were readmitted. Leading diagnoses were surgical site infection (23.2%) and cardiovascular event (16.8%). Of readmits 5.3% (5/95) were readmitted for failure to cope, representing 0.1% of the sample. In multivariate analysis, increased age was a significant predictor of readmission (OR = 0.974, 95% CI 0.952-0.997). Contrary to our hypothesis failure to cope was not a leading diagnosis for readmission; concerns remain that early discharge may however correlate with increased readmit rates.

Review of Kinemax total knee replacements performed at the NHS treatment centre, Weston-Super-Mare: five-year results

As part of the national initiative to reduce waiting times for joint replacement surgery in Wales, the Cardiff and Vale NHS Trust referred 224 patients to the NHS Treatment Centre in Weston-Super-Mare for total knee replacement (TKR). A total of 258 Kinemax TKRs were performed between November 2004 and August 2006. Of these, a total of 199 patients (232 TKRs, 90%) have been followed up for five years. This cohort was compared with 258 consecutive TKRs in 250 patients, performed at Cardiff and Vale Orthopaedic Centre (CAVOC) over a similar time period. The five year cumulative survival rate was 80.6% (95% confidence interval (CI) 74.0 to 86.0) in the Weston-Super-Mare cohort and 95.0% (95% CI 90.2 to 98.2) in the CAVOC cohort with revision for any reason as the endpoint. The relative risk for revision at Weston-Super-Mare compared with CAVOC was 3.88 (p < 0.001). For implants surviving five years, the mean Oxford knee scores (OKS) and mean EuroQol (EQ-5D) scores were similar (OKS: Weston-Super-Mare 29 (2 to 47) vs CAVOC 29.8 (3 to 48), p = 0.61; EQ-5D: Weston-Super-Mare 0.53 (-0.38 to 1.00) vs CAVOC 0.55 (-0.32 to 1.00), p = 0.79). Patients with revised TKRs had significantly lower Oxford knee and EQ-5D scores (p < 0.001). The results show a higher revision rate for patients operated at Weston-Super-Mare Treatment Centre, with a reduction in functional outcome and quality of life after revision. This further confirms that patients moved from one area to another for joint replacement surgery fare poorly.

Prosthetic hip dislocations: is relocation in the emergency department by emergency medicine staff better?

OBJECTIVE

Prosthetic hip dislocation is common. This study compares prosthetic hip relocations attempted within the ED by emergency doctors and those under orthopaedic care in the ED or operating theatre (OT).

METHODS

Retrospective cohort study of patients presenting to Auckland City Hospital Adult Emergency Department with prosthetic hip dislocations between 1 January 2003 and 14 April 2008. Primary outcomes were proportion of successful relocation attempts and length of hospital stay. Secondary outcomes were: time to relocation, complications, post-procedural advice, representation rate and long-term outcomes for first-time dislocations. There were 410 eligible presentations during the study period.

RESULTS

Emergency medicine (EM) was successful in 254/323 attempts (79%, 95% confidence interval [CI] 74-83). Orthopaedics were successful in 25/35 reductions in the ED (71%, 95% CI 55-84) and 49/51 OT attempts (96%, 95% CI 86-100), P = 0.004 for location OT versus ED. Median times to discharge were 8.8 h for EM, 28.3 h for orthopaedics in the ED and 81 h for orthopaedics in the OT, P < 0.001 for EM versus orthopaedics. Mechanical complications of procedures and early redislocations were infrequent. Complication of sedation were more often seen in OT compared to ED (23/47 [49%, 95% CI 35-63]vs 37/318 [12%, 95% CI 9-16]).

CONCLUSION

There was no difference between EM and orthopaedics in the proportion of hips successfully relocated or complications in the ED; however, EM patients were discharged much sooner, with important resource implications. Procedures carried out in the OT were more successful than in the ED but resulted in prolonged hospital stays and were associated with more complications.