Diagnostic Algorithm for Residual Pain After Total Knee Arthroplasty

Excellent 2-Year Outcomes of a Midlevel Constrained Liner Used in Stemless Primary TKA

Introduction

Instability after total knee arthroplasty (TKA) remains a leading cause of revision TKA and can lead to patient dissatisfaction. While many companies have developed midlevel constrained (MLC) polyethylene inserts in primary TKAs, there is little data on their outcomes.

Purpose

We sought to analyze short-term outcomes including survivorship, rates of manipulation under anesthesia (MUA), and improvements in patient-reported outcome measures (PROMs) preoperatively to postoperatively in one design of MLC TKA.

Methods

We prospectively followed consecutive primary TKA patients who received constrained inserts (Journey II or Legion Genesis II, Smith and Nephew) from 5 surgeons, 2019 to 2020, at a single academic institution. We analyzed revision-free survivorship, MUA rates, and PROMs, preoperatively to postoperatively.

Results

A total of 356 patients were included with a mean age of 64 years; 49% were male and the mean body mass index (BMI) was 31 kg/m2. Sixteen patients (4.5%) underwent MUA and 3 patients (0.8%) underwent revision. Two patients underwent polyethylene exchange and patellar resection for patellar loosening. One patient underwent liner exchange for instability. The 2-year revision-free survivorship was 98.5% (95% confidence interval [CI]: 96.6%-100%). Survivorship free from revision for tibial or femoral aseptic loosening was 100% at 2 years. The 2-year survivorship free from MUA was 92.3% (95% CI: 88.6%-96.1%). The mean Knee Osteoarthritis and Injury Outcomes Score Joint Replacement (KOOS JR) was 81 at 2 years follow-up, while the Lower Extremity Activity Score (LEAS) score was 10.5.

Conclusion

At a mean of 3 years follow-up, 2 types of MLCs used in primary TKA were associated with a low rate of early revision, low rate of MUA, and reliable improvement in functional outcomes. These MLCs were not associated with early loosening or unique failure modes.

Nickel allergy does not correlate with function after total knee arthroplasty

PURPOSE

The purpose of this study is to determine if there is a relationship between clinical outcomes and nickel allergy by evaluating asymptomatic total knee arthroplasty (TKA) patients with well-functioning implants through quantitative metal allergy (MA) testing.

METHODS

A prospective case series was performed on 50 patients with well-functioning TKA of various implant types. Inclusion criteria included primary TKA with a minimum 12-month follow-up and Oxford knee score (OKS) ≥ 40. A commercially available Lymphocyte Transformation Test measured the amount of a hypersensitivity lymphocyte immune response after exposure to a particular antigen. MA results were stratified based on the stimulation index (SI). The Cochran-Mantel-Haenzel test was used to test the homogeneity of metal reactivities. The Wilcoxon-Mann-Whitney test was used to compare individual metal SI by gender and the association of OKS and metal SI was ascertained with the Spearman correlation.

RESULTS

Nickel, cobalt, and chromium do not have the same reactivity scores (p < 0.001), and only nickel showed reactive/highly reactive scores. Females were found to have 3.41 times the odds of males for higher Ni reactivity (p = 0.0295, odds ratio [OR], 95% confidence interval [CI] = 3.41 [1.13-10.3]) only. Clinically, there was no correlation between metal SI and OKS score by metal (Ni rho = -0.1779; Co rho = -0.0036; Cr rho = -0.1748).

CONCLUSION

This is the first study looking at MA in well-functioning TKA. There is no correlation between clinical results and nickel reactivity. Surgeons should exercise caution when revising a painful or poorly functioning TKA based solely on a 'positive' Nickel Allergy test and look for other possible reasons for failure.

LEVEL OF EVIDENCE

Level II.

Perioperative intravenous dexamethasone did not reduce the severity of persistent postsurgical pain after total knee arthroplasty: a prospective, randomized, double-blind, placebo-controlled trial

BACKGROUND

Even with the great advancements in recent years in total knee arthroplasty (TKA), some patients continue to have persistent postsurgical pain (PPSP). The advantages of systemic corticosteroids in the perioperative context have been further supported by previously published trials. However, the impact of dexamethasone on the intensity of post-TKA PPSP is still unclear. We aimed to investigate its effect on the degree of PPSP and compare that with a placebo.

METHODS

In this randomized, double-blind, placebo-controlled study, 48 patients undergoing unilateral TKA were given intravenous dexamethasone 10 mg or saline just before spinal anesthesia was induced, and they also received two additional doses of dexamethasone 10 mg or saline 24 and 48 h after surgery. A standardized, multimodal analgesic regimen was administered to each patient. The modified WOMAC pain scores at 12 weeks postoperative were the main outcome. The secondary outcomes included pain during a walk of five meters, pain during active knee flexion at 45 degrees, maximum pain at rest during the previous 24 h, nausea visual analogue scale values, and use of rescue opioid and antiemetic medications.

RESULTS

There was no difference in modified WOMAC pain scores 12 weeks after surgery between patients who received and did not receive perioperative dexamethasone. At 24, 30, 48, 54, and 72 h following surgery, the dexamethasone group experienced considerably less pain during a five-meter walk and during 45 degrees active knee flexion (p < 0.01). At postoperative 0-24, 24-48, and 48-72 h, the dexamethasone group experienced less maximal pain at rest (p < 0.01). The dexamethasone group also had less visual analogue scale scores for nausea at 6, 24, 30, 48, and 54 h after surgery (p < 0.02). During the first 0-24 and 24-48 h, the dexamethasone group consumed fewer opioids and antiemetic medications (p < 0.01). All patients showed no signs of wound complications.

CONCLUSIONS

When compared to a placebo at 12 weeks after TKA, intravenous dexamethasone did not reduce PPSP. Nevertheless, early postoperative pain was relieved by perioperative intravenous dexamethasone, which also decreased the need for opioid and antiemetic medications and decreased postoperative nausea and vomiting.

TRIAL REGISTRATION

NCT02760459.

Isolated lateral-sided knee pain in total knee arthroplasty. A review

Isolated lateral-sided knee pain is a unique problem following total knee arthroplasty (TKA). Reported causes include soft tissue impingement against extruded cement, an overhanging tibial tray, remnant osteophytes rubbing against the iliotibial band (ITB), popliteal tendon impingement, fabella syndrome, and synovial tissue impingement in the lateral gutter. In addition, iliotibial band traction syndrome secondary to guided motion Bi-cruciate stabilizing knee arthroplasty has been recognized as a new clinical entity. Initial work up should include ruling out the most common causes of painful TKA including infection, aseptic loosening, and instability. Radiographs and CT scan are utilized to identify potential source of pain. Ultrasound evaluation (with elicited probe tenderness) can increase diagnostic accuracy. Ultrasound guided local anesthetic injections can confirm the source of pain. Anti-inflammatory medications, physical therapy with ITB stretches, and therapeutic local steroid injections are initial treatment modalities. Satisfactory resolution of symptoms may require surgical intervention directed at the specific cause and may avoid the morbidity associated with revision TKA.

Meta-analysis of factors influencing anterior knee pain after total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a mature procedure recommended for correcting knee osteoarthritis deformity, relieving pain, and restoring normal biomechanics. Although TKA is a successful and cost-effective procedure, patient dissatisfaction is as high as 50%. Knee pain after TKA is a significant cause of patient dissatisfaction; the most common location for residual pain is the anterior region. Between 4% and 40% of patients have anterior knee pain (AKP).

AIM

To investigate the effect of various TKA procedures on postoperative AKP.

METHODS

We searched PubMed, EMBASE, and Cochrane from January 2000 to September 2022. Randomized controlled trials with one intervention in the experimental group and no corresponding intervention (or other interventions) in the control group were collected. Two researchers independently read the title and abstract of the studies, preliminarily screened the articles, and read the full text in detail according to the selection criteria. Conflicts were resolved by consultation with a third researcher. And relevant data from the included studies were extracted and analyzed using Review Manager 5.4 software.

RESULTS

There were 25 randomized controlled trials; 13 were comparative studies with or without patellar resurfacing. The meta-analysis showed no significant difference between the experimental and control groups (P = 0.61). Six studies were comparative studies of circumpatellar denervation vs non-denervation, divided into three subgroups for meta-analysis. The two-subgroup meta-analysis showed no significant difference between the experimental and the control groups (P = 0.31, P = 0.50). One subgroup meta-analysis showed a significant difference between the experimental and control groups (P = 0.001). Two studies compared fixed-bearing TKA and mobile-bearing TKA; the results meta-analysis showed no significant difference between the experimental and control groups (P = 0.630). Two studies compared lateral retinacular release vs non-release; the meta-analysis showed a significant difference between the experimental and control groups (P = 0.002); two other studies compared other factors.

CONCLUSION

Patellar resurfacing, mobile-bearing TKA, and fixed-bearing TKA do not reduce the incidence of AKP. Lateral retinacular release can reduce AKP; however, whether circumpatellar denervation can reduce AKP is controversial.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

The Impact of Dorsal Root Ganglion Stimulation on Pain Levels and Functionality in Patients With Chronic Postsurgical Knee Pain

BACKGROUND

Chronic postsurgical pain is a considerable source of disabling neuropathic pain. Rates of knee replacement surgeries are increasing, and many patients report chronic postsurgical pain in their wake. When conventional therapies prove ineffective, neuromodulation options such as dorsal root ganglion stimulation (DRGS) may be used. However, little is known about the effect of DRGS on improvements in quantitative functional outcome parameters.

MATERIALS AND METHODS

In a prospective observational study at two pain centers, patients with chronic postsurgical knee pain underwent implantation with a DRGS system after an interdisciplinary multimodal pain program. Ratings of pain, mood, quality of life, and function were captured at baseline and through 12 months of treatment. Quantitative measures (range of motion, walking distance, and pain medication usage) were also recorded.

RESULTS

Visual analog scale ratings of pain decreased from 8.6 to 3.0 (p < 0.0001; N = 11), and other pain measures agreed. Quality of life on the 36-Item Short Form Health Survey questionnaire improved from 69.3 to 87.6 (p < 0.0001), whereas the improvement in depression ratings was nonsignificant. International Knee Documentation Committee questionnaire ratings of function improved from 27.7 to 51.7 (p < 0.0001), which aligned with other functional measures. On average, knee range of motion improved by 24.5°, and walking distance dramatically increased from 125 meters to 1481. Cessation of opioids, antidepressants, and/or anticonvulsants was achieved by 73% of participants.

CONCLUSIONS

Both subjective-based questionnaire and quantitative examination-based variables were in broad agreement on the value of DRGS in improving functionality and chronic postsurgical pain in the knee. Although this finding is limited by the small sample size, this intervention may have utility in the many cases in which pain becomes problematic after orthopedic knee surgery.

Peripheral nerve stimulation for chronic knee pain following total knee arthroplasty: a systematic review

Chronic knee pain following total knee arthroplasty (TKA) affects a subset of patients that is refractory to pharmacological and non-pharmacological modalities. Peripheral nerve stimulation (PNS) has been used in patients with chronic knee pain following TKA and has shown some efficacy. Methods: Comprehensive search of Ovid Medline, Elsevier Embase, Cochrane Central Register of Controlled Trials, CINAHL Plus with Full Text, Scopus, SPORTDiscus with Full Text and the Web of Science platform. From inception to August 2022, for studies using PNS to treat chronic knee pain following TKA. Primary outcomes included pain scores, functional status and medication usage. Results: Nine studies were extrapolated with all demonstrating effectiveness of PNS for patients with chronic knee pain following TKA. Discussion: PNS for chronic knee pain following TKA has been shown to be an efficacious treatment modality. The level of evidence is low and more research is needed to assess its safety and effectiveness.

ACR Appropriateness Criteria® Imaging After Total Knee Arthroplasty: 2023 Update

Total knee arthroplasty is the most commonly performed joint replacement procedure in the United States. This manuscript will discuss the recommended imaging modalities for six clinical variants; 1. follow-up of symptomatic or asymptomatic patients with a total knee arthroplasty. Initial imaging, 2. Suspected infection after total knee arthroplasty. Additional imaging following radiographs, 3. Pain after total knee arthroplasty. Infection excluded. Suspect aseptic loosening or osteolysis or instability. Additional imaging following radiographs, 4. Pain after total knee arthroplasty. Suspect periprosthetic or hardware fracture. Additional imaging following radiographs, 5. Pain after total knee arthroplasty. Measuring component rotation. Additional imaging following radiographs, and 6. Pain after total knee arthroplasty. Suspect periprosthetic soft-tissue abnormality unrelated to infection, including quadriceps or patellar tendinopathy. Additional imaging following radiographs. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Effectiveness of Geniculate Artery Embolization for Chronic Pain after Total Knee Replacement-A Pilot Study

PURPOSE

To evaluate the efficacy and safety of embolization of hyperemic synovial tissue for the treatment of persistent pain after total knee arthroplasty (TKA).

MATERIALS AND METHODS

Twelve patients with persistent pain after TKA were enrolled in this prospective, single-center pilot study. Genicular artery embolization (GAE) was performed using 75-μm spherical particles. The patients were assessed using a 100-point Visual Analog Scale (VAS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) at baseline and 3 and 6 months thereafter. Adverse events were recorded at all time points.

RESULTS

A mean of 1.8 ± 0.8 abnormal hyperemic genicular arteries were identified and embolized, with a median volume of diluted embolic material of 4.3 mL in all 12 (100%) patients. The mean VAS score on walking improved from 73 ± 16 at baseline to 38 ± 35 at the 6-month follow-up (P < .05). The mean KOOS pain score improved from 43.6 ± 15.5 at baseline to 64.6 ± 27.1 at the 6-month follow-up (P < .05). At the 6-month follow-up, 55% and 73% of the patients attained a minimal clinically important change in pain and quality of life, respectively. Self-limited skin discoloration occurred in 5 (42%) patients. The VAS score increased by more than 20 immediately after embolization in 4 (30%) patients, who required analgesic treatment for 1 week.

CONCLUSION

GAE is a safe method of treating persistent pain after TKA that demonstrates potential efficacy at 12 months.

What can we expect from patellar denervation in knee arthroplasty? An updated systematic review and meta-analysis

Denervation by electrocauterization was proposed to be efficient in preventing anterior knee pain (AKP) following arthroplasty. The purpose of this study was to evaluate the effects of patellar denervation (PD) in primary knee arthroplasty. Systematic search was performed in PubMed, ScienceDirect, Cochrane Library, and ClinicalKey databases until July 2022 for published articles. The quantitative analyses were carried out by Review Manager 5.4 software. Twenty-one studies were included. Overall incidence of AKP, visual analog scale (VAS), and knee society score were significantly superior in PD group. Denervation also showed better outcomes in incidence of AKP at each follow-up time point, and in VAS and range of motion (ROM) at ≤3 months. Subanalyses based on depth of electrocautery showed statistically better results with 2–3 mm depth in VAS and PS compared to ≤1 mm. This study concluded that PD might contribute to lower incidence of knee pain. Patients who expect quicker recovery in pain and ROM may benefit from this procedure.

Mid-Flexion Instability After Total Knee Arthroplasty: Diagnosis, Implant Design, and Outcomes

Mid-flexion instability (MFI) in total knee arthroplasty refers to a distinct clinical entity where the knee is stable at full extension and 90° of flexion, but unstable somewhere between these 2 points. The presentation of MFI is often vague, and studies defining objective clinical or intraoperative measurements are limited. In this review, we aim to properly define the condition, describe diagnostic criteria and risk factors contributing to MFI, review current implant design, and present outcomes of revision surgery performed for MFI. [Orthopedics. 2023;46(1):e13-e19.].

Femoral defects in revision hip arthroplasty: a therapy-oriented classification

INTRODUCTION

The complex field of femoral defects in revision hip arthroplasty displays a lack of standardized, intuitive pre- and intraoperative assessment. To address this issue, the femoral defect classification (FDC) is introduced to offer a reliable, reproducible and an intuitive classification system with a clear therapeutic guideline.

MATERIALS AND METHODS

The FDC is based on the integrity of the main femoral segments which determine function and structural support. It focuses on the femoral neck, the metaphysis consisting of the greater and lesser trochanter, and the femoral diaphysis. The four main categories determine the location of the defect while subcategories a, b and c are being used to classify the extent of damage in each location. In total, 218 preoperative radiographs were retrospectively graded according to FDC and compared to intraoperatively encountered bone defects. To account for inter-rater and intra-rater agreement, 5 different observers evaluated 80 randomized cases at different points in time.

RESULTS

A Cohens kappa of 0.832 ± 0.028 could be evaluated, accounting for excellent agreement between preoperative radiographs and intraoperative findings. To account for inter-rater reliability, 80 patients have been evaluated by 5 different observers. Testing for inter-rater reliability, a Fleiss Kappa of 0.688 could be evaluated falling into the good agreement range. When testing for intra-rater reliability, Cohens Kappa of each of the 5 raters has been analyzed and the mean was evaluated at 0.856 accounting for excellent agreement.

CONCLUSION

The FDC is a reliable and reproducible classification system. It combines intuitive use and structured design and allows for consistent preoperative planning and intraoperative guidance. A therapeutic algorithm has been created according to current literature and expert opinion. Due to the combination of the FDC with the recently introduced Acetabular Defect Classification (ADC) a structured approach to the entire field of hip revision arthroplasty is now available.

Mismatch between trochlear coronal alignment of arthritic knees and currently available prosthesis: a morphological analysis of 4116 knees and 45 implant designs

PURPOSE

In up to a fifth of total knee replacements (TKR), surgeons are not capable of achieving good clinical and functional results. Despite comprehensive diagnostic workup, an underlying cause is not always identified in these patients. The purpose of this study is to compare native and prosthetic trochlear anatomies, to evaluate a potential source of morphologic mismatch and theoretically, of poor clinical outcomes.

METHODS

Native trochlear angles of 4116 knee CTs from 360 Knee Systems database of arthritic pre-operative TKR patients were evaluated. A semi-automated tridimensional analysis was performed to define the native trochlear angle in the coronal plane (NTA) among other 142 parameters. An active search was conducted to identify currently available TKR models; prosthetic trochlear orientation in the coronal plane (PTA) was extracted from the technical data provided by manufacturers.

RESULTS

The mean native trochlear angle (NTA) was 1.6° ± 6.6° (valgus) with a range from - 23.8° (varus) to 30.3°(valgus). A valgus NTA was present in 60.6% of the knees and 39.4% of them had a varus NTA. 89 TKR models were identified; trochlear details were available for 45 of them, of which 93% were designed with a valgus orientation of the prosthetic trochlear angle (PTA) and 6.9% showed a neutral (0°) PTA. Varus alignment of PTA was not present in any system. Angular numeric values for PTA were available for 34 models; these ranged from 0° to 15° of valgus, with a median value of 6.18° (SD ± 2.88°).

CONCLUSION

This study shows a significant mismatch between native and prosthetic trochlear angles. A relevant proportion of the studied knees (41.45%) fall out of the trochlear angle range of currently available implants; representing a potential source for biomechanical imbalance. While further research is warranted to fully understand the clinical implications of the present study, manufacturers may need to take these findings into account for future implant designs.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Impact of patient and prosthesis characteristics on common reasons for total knee replacement revision: a registry study of 36,626 revision cases from Australia, Sweden, and USA

BACKGROUND AND PURPOSE

Total knee replacement (TKR) studies usually analyze all-cause revision when considering relationships with patient and prosthesis factors. We studied how these factors impact different revision diagnoses.

PATIENTS AND METHODS

We used data from 2003 to 2019 of TKR for osteoarthritis from the arthroplasty registries of Sweden, Australia, and Kaiser Permanente, USA to study patient and prosthesis characteristics for specific revision diagnoses. There were 1,072,924 primary TKR included and 36,626 were revised. Factors studied included age, sex, prosthesis constraint, fixation method, bearing mobility, polyethylene type, and patellar component use. Revision diagnoses were arthrofibrosis, fracture, infection, instability, loosening, pain, patellar reasons, and wear. Odds ratios (ORs) for revision were estimated and summary effects were calculated using a meta-analytic approach.

RESULTS

We found between-registry consistency in 15 factor/reason analyses. Risk factors for revision for arthrofibrosis were age < 65 years (OR 2.0; 95% CI 1.4-2.7) and mobile bearing designs (MB) (OR 1.7; CI 1.1-2.5), for fracture were female sex (OR 3.2; CI 2.2-4.8), age ≥ 65 years (OR 2.8; CI 1.9-4) and posterior stabilized prostheses (PS) (OR 2.1; CI 1.3-3.5), for infection were male sex (OR 1.9; CI 1.7-2.0) and PS (OR 1.5; CI 1.2-1.8), for instability were age < 65 years (OR 1.5; CI 1.3-1.8) and MB (OR 1.5; CI 1.1-2.2), for loosening were PS (OR 1.5; CI 1.4-1.6), MB (OR 2.2; CI 1.6-3.0) and use of ultra-high molecular weight polyethylene (OR 2.3; CI 1.8-2.9), for patellar reasons were not resurfacing the patella (OR 13.6; CI 2.1-87.2) and MB (OR 2.0; CI 1.2-3.3) and for wear was cementless fixation (OR 4.9; CI 4.3-5.5).

INTERPRETATION

Patients could be counselled regarding specific age and sex risks. Use of minimally stabilized, fixed bearing, cemented prostheses, and patellar components is encouraged to minimize revision risk.

Arthroscopic management of unexplained pain following total knee arthroplasty

INTRODUCTION

Arthrofibrosis develops in 3-10% of knees after total knee arthroplasty (TKA), which may result in pain and restricted range-of-motion. Treatment options include manipulation under anaesthesia, arthroscopic debridement, and quadricepsplasty, but there is little consensus on their efficacy for treatment of unexplained pain after TKA. The purpose of this study was to report the prevalence and characteristics of unexplained pain after TKA as revealed by arthroscopic exploration, and assess the efficacy of arthroscopic procedures to relieve pain.

MATERIALS AND METHODS

From a consecutive series of 684 TKAs, 11 patients (1.6%) had unexplained pain at 7-48 months after TKA. Causes of pain remained unidentified after systematic and differential assessment, but arthroscopic exploration revealed fibrotic tissues, which were debrided during the same procedure. Patients were assessed first at 6-61 months and last at 90-148 months, with pain on a visual analog scale (pVAS) and range-of-motion recorded during both assessments, but Oxford Knee Score (OKS) and Forgotten Joint Score (FJS) only during the last assessment. Residual pain was classified as little or no pain (pVAS, 0-1), moderate pain (pVAS, 2-4), and severe pain (pVAS, 5-10).

RESULTS

At first follow-up (n = 11) pVAS improved by 4.1 ± 1.1 (p < 0.001), and range-of-motion improved by 5.0° ± 7.1° (p = 0.041). Seven patients (64%) had little or no residual pain, while four (36%) had moderate residual pain. At final follow-up (n = 9) pVAS improved by 3.2 ± 2.9 (p < 0.001), and range-of-motion improved by 4.4° ± 8.5° (p = 0.154). Six patients (67%) had little or no residual pain, while one (11%) had moderate and two (22%) had severe residual pain.

CONCLUSION

Arthroscopic exploration revealed that all 11 knees with unexplained pain had fibrotic tissues, the removal of which alleviated pain in only 67%, while moderate to severe pain persisted in 33% which merits further scrutiny.

A Mid-Level Constrained Insert Reduces Coupled Axial Rotation but Not Coronal Mid-Flexion Laxity Induced by Joint Line Elevation in Posterior-Stabilized Total Knee Arthroplasty: A Computational Study

BACKGROUND

Surgeons may resect additional distal femur during primary posterior-stabilized (PS) total knee arthroplasty (TKA) to correct a flexion contracture. However, the resultant joint line elevation (JLE) increases mid-flexion laxity. We determined whether a mid-level constraint (MLC) insert reduced mid-flexion laxity after JLE.

METHODS

Six computational knee models were developed using computed tomography scans and average soft tissue properties yielding balanced extension gaps but with a 10° flexion contracture. Distal femoral resections of +2 and +4 mm were simulated with PS and MLC inserts. Varus-valgus ±10 Nm moments were applied at 30°, 45°, and 60° of flexion. Coronal laxity (the sum of varus-valgus angulation) and coupled axial rotation (the sum of internal/external rotation) were measured and compared between insert models.

RESULTS

At 30° of flexion, coronal laxities with the PS insert at the +2 and +4 mm resections averaged 7.9° ± 0.6° and 11.3° ± 0.6°, respectively, and decreased by 0.8° (P = .06) and 1.0° (P = .07), respectively, with the MLC insert. PS rotational laxities at the +2 and +4 mm resections averaged 11.1° ± 3.9° and 12.5° ± 4.6°, respectively, and decreased by 5.6° (P = .01) and 7.1° (P = .02), respectively, with the MLC insert. Similar patterns were observed at 45° and 60° of flexion.

CONCLUSION

With additional distal femoral resections to alleviate a flexion contracture, utilizing an MLC insert substantially reduced coupled axial rotation but had a minimal impact on coronal laxity compared to a PS insert. Efforts should be taken to avoid JLE in primary total knee arthroplasty as even MLC inserts may not mitigate coronal laxity.

Diagnosis of Central Sensitization and Its Effects on Postoperative Outcomes following Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Central sensitization (CS) has been extensively researched as a cause of persistent pain after total knee arthroplasty (TKA). This systematic review study sought to investigate the diagnosis of CS in patients who underwent TKA for knee osteoarthritis (OA) and the effect of CS on clinical outcomes after TKA. Three comprehensive databases, including MEDLINE, EMBASE, and the Cochrane Library, were searched for studies that evaluated the outcomes of TKA in knee OA patients with CS. Data extraction, risk of bias assessment, and (where appropriate) meta-analysis were performed. The standardized mean difference (SMD) with a 95% confidence interval was used to assess the different scales of pain. A total of eight studies were selected, including two retrospective studies and five prospective observational studies. One study used additional randomized controlled trial data. Five studies were finally included in the meta-analysis. All studies had a minimum follow-up period of 3 months. The Central Sensitization Inventory (CSI), whole-body pain diagram, and quantitative sensory testing (QST) were used for measuring CS. The pooled analysis showed that patients with CS had more severe postoperative pain after TKA (SMD, 0.65; 95% CI, 0.40−0.90; p < 0.01) with moderate heterogeneity (I2 = 60%). In patients who underwent TKA with knee OA, CSI is most often used for the diagnosis of CS, and the QST and whole-body pain diagram are also used. CS is closely associated with more severe and persistent pain after TKA.

Metal Hypersensitivity or Missed Periprosthetic Joint Infection? A Critical Review

The World Association Against Infection in Orthopedics And Trauma (W.A.I.O.T.) Study Group on Bone And Joint Infection Definitions Metal hypersensitivity (MHS) has been investigated by several authors as a possible reason for painful total joint arthroplasty, with controversial results. Periprosthetic joint infection (PJI) is another possible source of unexplained pain and implant failure that may be difficult to diagnose if not properly investigated. We performed this critical review to assess whether the current literature on MHS includes an adequate diagnostic workup to discern metal allergy from PJI. The results of this review highlight the importance of assessing patients for PJI before making a diagnosis of MHS and emphasize that the methods currently used to exclude PJI are substantially inadequate. Therefore, well-designed clinical trials with adequate diagnostic protocols and definitions of PJI that can differentiate MHS from low-grade PJI are needed. [Orthopedics. 2022;45(2):e73-e78.].

Stress-Induced, Aseptic Osteolysis of the Mid-Tibia in a Revision Hinged Total Knee Arthroplasty Mimicking Infection

In this report, we present the case of an 80-year-old female with pain located over the tip of her cemented tibial stem in a revision hinge total knee arthroplasty with localized osteolysis that looked suspicious for infection. A thorough workup was negative for infection. We postulate that the osteolysis at the end of her tibial stem was initiated by a modulus of elasticity mismatch at the stem tip, which generated a focal area of increased sagittal bone bending and microparticle generation. She was treated with lesional exploration, debridement, synthetic bone grafting, and tibial plating to distribute stress loads away from the tibial stem tip. Histologic analysis identified no organisms or neoplasm. Her pain ultimately resolved, and the patient returned to her customary activities.

The lifetime risk of revision following total knee arthroplasty : a New Zealand Joint Registry study

AIMS

The success of total knee arthroplasty (TKA) is usually measured using functional outcome scores and revision-free survivorship. However, reporting the lifetime risk of revision may be more meaningful to patients when gauging risks, especially in younger patients. We aimed to assess the lifetime risk of revision for patients in different age categories at the time of undergoing primary TKA.

METHODS

The New Zealand Joint Registry database was used to obtain revision rates, mortality, and the indications for revision for all primary TKAs performed during an 18-year period between January 1999 and December 2016. Patients were stratified into age groups at the time of the initial TKA, and the lifetime risk of revision was calculated according to age, sex, and the American Society of Anesthesiologists (ASA) grade. The most common indications for revision were also analyzed for each age group.

RESULTS

The overall ten-year survival rate was 95.6%. This was lowest in the youngest age group (between 46 and 50 years) and increased sequentially with increasing age. The lifetime risk of requiring revision was 22.4% in those aged between 46 and 50 years at the time of the initial surgery, and decreased linearly with increasing age to 1.15% in those aged between 90 and 95 years at the time of surgery. Higher ASA grades were associated with increased lifetime risk of revision in all age groups. The three commonest indications for revision were aseptic loosening, infection, and unexplained pain. Young males, aged between 46 and 50 years, had the highest lifetime risk of revision (25.2%).

CONCLUSION

Lifetime risk of revision may be a more meaningful measure of outcome than implant survival at defined time periods when counselling patients prior to TKA. This study highlights the considerably higher lifetime risk of revision surgery for all indications, including infection, in younger male patients. Cite this article: Bone Joint J 2022;104-B(2):235-241.

Evaluation and Management of a Painful Knee After Total Knee Arthroplasty

Pain after total knee arthroplasty (TKA) is not infrequent and may be indicative of a broad spectrum of prosthesis-related, intra-articular, or extra-articular pathologies. To diagnose and treat the underlying cause of a painful TKA, systematic evaluation of the patient is critical to ensure that they are managed appropriately and expeditiously. This evidence-based review presents current concepts regarding the pathophysiology, etiology, and diagnosis of painful TKA and our recommended approach for management. [Orthopedics. 2021;44(6):341-352.].

A retrospective study on patients with chronic knee pain treated with ultrasound-guided radiofrequency of the genicular nerves (RECORGEN trial)

INTRODUCTION

Radiofrequency (RF) treatment of the genicular nerves is a promising treatment for chronic osteoarthritic and persistent postsurgical knee pain (PPSP), refractory to conventional medical management.

METHODS

The RECORGEN study is a retrospective single-center cohort study of patients treated with ultrasound-guided conventional RF of the genicular nerves for chronic knee pain in Hospital Oost-Limburg, Genk from September 2017 to June 2020. Subgroup analysis based on etiology of pain (PPSP and degenerative knee pain) was performed in addition to the total study population analysis. Outcome parameters were global perceived effect (GPE), Numeric Rating Scale for pain, consumption of strong opioids, and safety of the treatment at 6 weeks and cross-sectionally at a variable time point. Treatment success was defined as GPE≥50%.

RESULTS

Sixty-eight cases were screened of which 59 (46 diagnosed with PPSP and 13 with degenerative knee pain) were included in the study. Treatment success at 6 weeks was achieved in 19 of 59 interventions (32.2%) and was similar in both groups. Seventeen responders were evaluated at follow-up. 45.1% (8/17) continued to have a positive effect at the second time point. The mean duration of effect of the RF treatment was 8.3 months. Safety analysis at 6 weeks and at the second time point showed a good safety profile of the treatment.

CONCLUSION

Conventional RF of the genicular nerves was clinically successful in more than 30% of the study population refractory to conventional medical management. Overall, the treatment was well tolerated. The mean duration of effect was 8.3 months.

Classification algorithm for the International Classification of Diseases-11 chronic pain classification: development and results from a preliminary pilot evaluation

ABSTRACT

The International Classification of Diseases-11 (ICD-11) chronic pain classification includes about 100 chronic pain diagnoses on different diagnostic levels. Each of these diagnoses requires specific operationalized diagnostic criteria to be present. The classification comprises more than 200 diagnostic criteria. The aim of the Classification Algorithm for Chronic Pain in ICD-11 (CAL-CP) is to facilitate the use of the classification by guiding users through these diagnostic criteria. The diagnostic criteria were ordered hierarchically and visualized in accordance with the standards defined by the Society for Medical Decision Making Committee on Standardization of Clinical Algorithms. The resulting linear decision tree underwent several rounds of iterative checks and feedback by its developers, as well as other pain experts. A preliminary pilot evaluation was conducted in the context of an ecological implementation field study of the classification itself. The resulting algorithm consists of a linear decision tree, an introduction form, and an appendix. The initial decision trunk can be used as a standalone algorithm in primary care. Each diagnostic criterion is represented in a decision box. The user needs to decide for each criterion whether it is present or not, and then follow the respective yes or no arrows to arrive at the corresponding ICD-11 diagnosis. The results of the pilot evaluation showed good clinical utility of the algorithm. The CAL-CP can contribute to reliable diagnoses by structuring a way through the classification and by increasing adherence to the criteria. Future studies need to evaluate its utility further and analyze its impact on the accuracy of the assigned diagnoses.

Additional distal femoral resection increases mid-flexion coronal laxity in posterior-stabilized total knee arthroplasty with flexion contracture : a computational study

AIMS

Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture, which leads to femoral joint line elevation. There is a paucity of data describing the effect of joint line elevation on mid-flexion stability and knee kinematics. Thus, the goal of this study was to quantify the effect of joint line elevation on mid-flexion laxity.

METHODS

Six computational knee models with cadaver-specific capsular and collateral ligament properties were implanted with a posterior-stabilized (PS) TKA. A 10° flexion contracture was created in each model to simulate a capsular contracture. Distal femoral resections of + 2 mm and + 4 mm were then simulated for each knee. The knee models were then extended under a standard moment. Subsequently, varus and valgus moments of 10 Nm were applied as the knee was flexed from 0° to 90° at baseline and repeated after each of the two distal resections. Coronal laxity (the sum of varus and valgus angulation with respective maximum moments) was measured throughout flexion.

RESULTS

With + 2 mm resection at 30° and 45° of flexion, mean coronal laxity increased by a mean of 3.1° (SD 0.18°) (p < 0.001) and 2.7° (SD 0.30°) (p < 0.001), respectively. With + 4 mm resection at 30° and 45° of flexion, mean coronal laxity increased by 6.5° (SD 0.56°) (p < 0.001) and 5.5° (SD 0.72°) (p < 0.001), respectively. Maximum increased coronal laxity for a + 4 mm resection occurred at a mean 15.7° (11° to 33°) of flexion with a mean increase of 7.8° (SD 0.2°) from baseline.

CONCLUSION

With joint line elevation in primary PS TKA, coronal laxity peaks early (about 16°) with a maximum laxity of 8°. Surgeons should restore the joint line if possible; however, if joint line elevation is necessary, we recommend assessment of coronal laxity at 15° to 30° of knee flexion to assess for mid-flexion instability. Further in vivo studies are warranted to understand if this mid-flexion coronal laxity has negative clinical implications. Cite this article: Bone Joint J 2021;103-B(6 Supple A):87-93.

Efficacy and safety of duloxetine for postoperative pain after total knee arthroplasty in centrally sensitized patients: study protocol for a randomized controlled trial

Background

Postoperative residual knee pain after total knee arthroplasty (TKA) is a significant factor that contributes to patient dissatisfaction. Patients with preoperative central sensitization (CS) may be more susceptible to unexplained chronic pain after TKA, and duloxetine has been reported to be effective in post-TKA pain control in patients with CS. However, there remains limited evidence to support this off-label use in routine clinical practice. Hence, we designed this randomized, placebo-controlled, triple-blind clinical trial to evaluate the effects of preoperative screening and targeted duloxetine treatment of CS on postoperative residual pain compared with the care-as-usual control group.

Methods

This randomized controlled trial includes patients with knee osteoarthritis on a waiting list for primary unilateral TKA. Patients with preoperative CS will be randomly allocated to the perioperative duloxetine treatment group (duloxetine group) or the care-as-usual control group (placebo group). Patients in the duloxetine group will receive a half-dose of preemptive duloxetine (30 mg/day) for a week before surgery and a full-dose of duloxetine (60 mg/day) for six weeks after surgery. The primary outcome is the intensity of residual pain at six months after TKA, including the visual analogue scale, 11-point numeric rating scale, the sensory dimension of the brief pain inventory, and the pain subscale of the Knee injury and Osteoarthritis Outcome Score. The secondary outcome measures will include the pain and function related outcomes. All of the patients will be followed up at one, three, and six months after surgery. All adverse events will be recorded and immediately reported to the primary investigator and ethics committee to decide if the patient needs to drop out from the trial.

Discussion

This clinical trial will convey the latest evidence of the efficacy and safety of the application of duloxetine in postoperative pain control in CS patients who are scheduled for TKA. The study results will be disseminated at national and international conferences and published in peer-reviewed journals.

Trial registration

Chinese Clinical Trial Registry (http://www.chictr.org.cn) registration number: ChiCTR2000031674. Registered 07 April 2020.

Public Interest in Knee Pain and Knee Replacement during the SARS-CoV-2 Pandemic in Western Europe

Due to the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) pandemic, a large number of elective knee replacement procedures had to be postponed in both early and late 2020 in most western countries including Germany and the UK. It is unknown how public interest and demand for total knee arthroplasties was affected. Public interest in knee pain, knee osteoarthritis and knee arthroplasty in Germany and the UK was investigated using Google Trend Analysis. In addition, we monitored for changes in patient composition in our outpatient department. As of early March in Germany and of late March in the UK, until the lockdown measures, a 50 to 60% decrease in relative search frequency was observed in all categories investigated compared to the beginning of the year. While public interest for knee pain rapidly recovered, decreased interest for knee osteoarthritis and replacement lasted until the easing of measures. Shortly prior to and during the first lockdown mean search frequency for knee replacement was significantly decreased from 39.7% and 36.6 to 26.9% in Germany and from 47.7% and 50.9 to 23.7% in the UK (Germany: p = 0.022 prior to lockdown, p < 0.001 during lockdown; UK: p < 0.0001 prior to and during lockdown). In contrast, mean search frequencies did not differ significantly from each other for any of the investigated time frames during the second half of 2020 in both countries. Similarly, during the first lockdown, the proportion of patients presenting themselves to receive primary knee arthroplasty compared to patients that had already undergone knee replacement declined markedly from 64.7% to 46.9%. In contrast, patient composition changed only marginally during the lockdown measures in late 2020 in both Germany and the UK. We observed a high level of public interest in knee arthroplasty despite the ongoing pandemic. The absence of a lasting decline in interest in primary knee arthroplasty suggests that sufficient symptom reduction cannot be achieved without surgical care for a substantial number of patients.

The role of metal patch testing in evaluating patients for metallic prosthetic joint failure

BACKGROUND

Metal allergy may be an uncommon cause of prosthetic joint failure. There exist little data on patch testing to metals in this context and its impact on outcomes of joint revision in these patients.

OBJECTIVE

To explore the use and indications for metal patch testing in the evaluation of patients suspected of having metal allergy as a cause of failed joint replacements and to clarify the outcomes of patients revised with alternative metallic joints because of positive patch testing result.

METHODS

A retrospective analysis from January 2016 to April 2020 was completed on a patient cohort referred for evaluation of metal hypersensitivity. Charts were reviewed for age, biological sex, referring specialty, patch testing results, joint, revision status, and outcome measures. Biostatistical analysis and descriptive statistics were performed to determine patch testing performance and functional outcome trends among this patient cohort.

RESULTS

The sensitivity and specificity of patch testing, in general, are limited when evaluating patients with metallic joint replacements. However, the predictive value of testing seemed to improve with strongly positive patch testing results. Functional outcomes in patients when positive results were used to guide revision prosthesis revealed clinical improvement.

CONCLUSION

The attribution of metal allergy or hypersensitivity as a cause of failure in metal prosthetic joint replacement remains unproven. Some patients with positive histories and patch testing results that were used to modify the implanted prosthesis had improved functional outcomes. These results suggest that patch testing may be useful in patients with history of metal sensitivity and prosthetic failure.

Complex Regional Pain Syndrome Following Total Knee Arthroplasty

Complex regional pain syndrome (CRPS) is an uncommon cause of residual pain after total knee arthroplasty (TKA). The presentation is variable, and there is no gold standard diagnostic test. Diagnosis is more difficult after TKA because some classic signs of CRPS may be unreliable and imaging may be difficult to interpret. Early intervention is the most important factor in predicting improvement, necessitating high suspicion in patients with exaggerated pain and stiffness after excluding more common causes. This article reviews the literature regarding CRPS following TKA, explains the diagnosis, and discusses treatment. [Orthopedics. 2020;43(6):e486-e491.].

Endovascular Occlusion of Neovascularization as a Treatment for Persistent Pain After Total Knee Arthroplasty

Approximately 20% of patients have persistent unexplained pain after total knee arthroplasty (TKA). Currently available treatments are unsatisfactory. The present report describes four patients in whom transcatheter arterial embolization had a remarkable effect on pain after TKA. Abnormal neovessels were identified in all patients. For 48 h, one patient experienced remarkable postprocedural pain at the inner side of the knee that was subsided by level 1 analgesics and another patient development of a spontaneous skin ulceration resolving within 8 days. The mean Knee injury and Osteoarthritis Outcome Score pain subtotal had increased from 39 to 82 one month after treatment. Endovascular occlusion of neovascularization, decreasing chronic inflammation and the growth of unmyelinated sensory nerves may be treatment options for persistent unexplained pain following TKA.Level of Evidence IV, Case report.

Loosening of total knee arthroplasty - always aseptic?

PURPOSE

When revision surgery is needed in total knee arthroplasty (TKA) the most frequent reasons are aseptic loosening (AL) and periprosthetic joint infection (PJI). However preoperative distinction between AL and PJI remains challenging. Aim of this study is to determine the incidence of PJI in patients with suspected AL after TKA and to evaluate a diagnostic algorithm for reliable differential diagnosis.

METHODS

In this study a total of 149 symptomatic patients with radiographic signs of prosthetic loosening and suspected AL were included. Preoperatively all patients underwent a standardized diagnostic algorithm. For each patient demographics, as well as the results of laboratory and microbiological testing were collected from the medical records.

RESULTS

Of the included patients 117 (78.5%) were diagnosed with AL and 32 (21.5%) with PJI. The latency period from primary arthroplasty to the presentation with symptomatic implant loosening was significantly shorter for PJI compared to AL (p < 0.05). The initial CRP values were significantly higher in patients with PJI compared to patients with AL (p < 0.05). Elevated count of white blood cells or percentage of neutrophils within the synovial fluid support the diagnosis of PJI. The sensitivity of synovial cell count (CC) count for PJI in patients with radiographic signs of loosening was 0.84 (CI 0.81-0.87) with a specificity of 0.96 (CI 0.92-0.98). The single best measure for the diagnosis of PJI was synovial fluid cultures with a specificity of 1, however this measure provides poor sensitivity.

CONCLUSION

Patients with radiographic signs of loosening in TKA need thorough diagnostics. Information about primary TKA, serological testing, and results of joint aspiration can rule out a PJI in most cases.

Mechanical alignment changes during flexion in total knee arthroplasty without affecting clinical outcomes

BACKGROUND

Primary aim of this study is to investigate if Hip-Knee-Ankle angle, measured in the coronal plane, changes with knee flexion after total knee arthroplasty. The secondary aim is to assess the relationship between Hip-Knee-Ankle during knee flexion and clinical outcome at mid-term follow up.

METHODS

334 computer assisted total knee arthroplasties were retrospectively evaluated. A total of 233 patients were available for assessment of clinical outcomes at last follow up (mean 35 months). Hip-Knee-Ankle angle at different degrees of knee flexion and components' alignment were recorded intraoperatively.

FINDINGS

Patients were stratified based on the preoperative alignment: 202 varus knees, 99 neutral knees, and 33 valgus knees. In the varus knee group, 146 patients (89%) maintained a neutral overall limb alignment when flexed to 20°, 118 (72%) remained neutrally aligned at 45° and 92 (54%) at 90°. In valgus knee group, 26 (90%) remained neutrally aligned at 20°, 22 (75%) at 45° and 16 (55%) at 90°. In neutrally-aligned knee group, 88 (96%) remained neutrally aligned at 20°, 73 (79%) at 45° and 61 (66%) at 90°. Femoral component external rotation was correlated with varus alignment in flexion. Good outcomes were reported in 181 (78%) cases, fair results in 28 (12%) cases, poor results in 24 (10%) of cases. Poor results were not correlated to Hip-Knee-Ankle angle at different knee flexion angles.

INTERPRETATION

This study demonstrates that intraoperative Hip-Knee-Ankle angle changes as the knee moves into deeper flexion. However, neutral Hip-Knee-Ankle through the range of motion does not correlate with superior outcomes.

Two-Stage Revision Total Knee Arthroplasty for Suspected Periprosthetic Joint Infection and Metal and Bone Cement Hypersensitivity

Hypersensitivity to implant components and periprosthetic joint infection should be detected before all revision arthroplasty, as misdiagnosis can lead to replacement loosening and the need for further revision procedures. We describe the case of a 69-year-old woman presenting a history of a painful cemented total knee replacement. Postoperative investigations showed loosening of X-ray components, suspected periprosthetic joint infection, and patch test hypersensitivity to nickel sulfate and methyl methacrylate. Two months later, a more specific patch test indicated non-allergy to the solid scratch of one bone cement. The patient underwent a two-stage revision with prosthesis removal and the temporary application of a specific cement spacer followed by the successful reimplantation of a cemented revision prosthesis. All candidates for the revision arthroplasty procedure must be investigated for hypersensitivity to metal and bone cement in order to avoid complications related to prosthesis intolerance and the need for further revision surgery; in the presence of hypersensitivity to bone cement and periprosthetic joint infection with a two-stage revision indication, the patient must be submitted to further patch tests with scratches of solid bone cement.

Prospective, observational study to evaluate the relation between patient-reported outcomes and component rotation in total knee replacement: protocol for the CRACK study

INTRODUCTION

Total knee replacement (TKR) for osteoarthritis results in a satisfactory outcome in the majority of patients, although up to one in five patients may be dissatisfied with the outcome. Persistent pain is a main contributor to patient dissatisfaction, and femoral and tibial component malrotation have been identified as a potential cause for both persistent pain and patellofemoral problems. Based on the assumption that component malrotation is the causative factor for persistent pain, early revision for patients with symptomatic malrotated components has been advocated in the literature. However, convincing evidence that component malrotation indeed results in less than optimal outcomes is lacking. This study aims to assess the relation between knee prosthesis component rotation and patient-reported outcomes in a large group of patients and to determine the range of femoral, tibial and combined rotation that results in the best clinical outcomes.

METHODS AND ANALYSIS

In this single-centre, prospective observational cohort study, a total of 500 patients will undergo TKR. All patients will have a 3D-CT assessment of femoral and tibial component rotation within 8 weeks after surgery. Outcome measures will include the Oxford Knee Score, the Knee Injury and Osteoarthritis Outcome Score, EQ-5D, visual analogue scale for pain, the American Knee Society Score and the knee joint range of motion. We will assess the relation between femoral, tibial and combined component rotation and patient-reported outcome measures at 8 weeks and 1 year of follow-up, and we will determine the range of femoral, tibial and combined rotation that results in the best clinical outcomes.

ETHICS AND DISSEMINATION

Ethical approval for this study has been granted by the Isala Hospital ethics committee. The results will be published in a peer-reviewed journal and presented at relevant meetings.

TRIAL REGISTRATION NUMBER

NL7635.

Does navigated patellar resurfacing in total knee arthroplasty result in proper bone cut, motion and clinical outcomes?

BACKGROUND

In total knee arthroplasty with patellar resurfacing, patellar bone preparation, component positioning and motion assessments are still not navigated. Only femoral/tibial component positioning is supported by computer-assistance. The aim of this study was to verify, in-vivo, whether knee surgical navigation extended to patellar resurfacing, by original instrumentation and procedures for patellar-based tracking, could achieve accurate patella preparation in terms of original thickness restoration, bone cut orientation, and normal knee motion.

METHODS

An additional navigation system for patellar data acquisition was used together with a standard navigation system for total knee arthroplasty in 20 patients. This supported the surgeon for patellar resurfacing via measurement of removed bone thickness, three-dimensional patellar cut orientations, and patello-femoral motion. Radiological and clinical examinations at 6 and 24-month follow-up were also performed.

FINDINGS

The medio-lateral patellar-bone cut orientation was respectively 0.5° (standard deviation: 3.0°) and 1.4° (1.7°) lateral tilt, as measured via navigation and post-operatively on the Merchant x-ray view. The cranio-caudal orientation was 3.8° (7.2°) of flexion. The thickness variation between patellar pre- and post-implantation was 0.2 (1.3) mm. Immediately after implantation, patello-femoral as well as tibio-femoral kinematics was within the normality. Good radiological and clinical examinations at 6 and 24-month follow-up were also observed.

INTERPRETATION

For the first time, the effect of patellar navigation for its resurfacing was assessed in-vivo during surgery, with very good results for thickness restoration, proper cut orientation, and normal knee motion. These results support the introduction of patella-related navigation-based surgical procedures for computer-assisted total knee arthroplasty.

Allergy in total knee replacement surgery: Is it a real problem?

Total knee arthroplasty is a common procedure, with extremely good clinical results. Despite this success, it produces 20% unsatisfactory results. Among the causes of these failures is metal hypersensitivity. Metal sensitization is higher in patients with a knee arthroplasty than in the general population and is even higher in patients undergoing revision surgery. However, a clear correlation between metal sensitization and symptomatic knee after surgery has not been ascertained. Surely, patients with a clear history of metal allergy must be carefully examined through dermatological and laboratory testing before surgery. There is no globally accepted diagnostic algorithm or laboratory test to diagnose metal hypersensitivity or metal reactions. The patch test is the most common test to determine metal hypersensitivity, though presenting some limitations. Several laboratory assays have been developed, with a higher sensitivity compared to patch testing, yet their clinical availability is not widespread, due to high costs and technical complexity. Symptoms of a reaction to metal implants present across a wide spectrum, ranging from pain and cutaneous dermatitis to aseptic loosening of the arthroplasty. However, although cutaneous and systemic hypersensitivity reactions to metals have arisen, thereby increasing concern after joint arthroplasties, allergies against implant materials remain quite rare and not a well-known problem. The aim of the following paper is to provide an overview on diagnosis and management of metal hypersensitivity in patients who undergo a total knee arthroplasty in order clarify its real importance.

Patellar complications after total knee arthroplasty

Patellar complications are a source of poor total knee arthroplasty (TKA) outcomes that can require re-operation or prosthetic revision. Complications can occur with or without patellar resurfacing. The objective of this work is to answer six questions. (1) Have risk factors been identified, and can they help to prevent patellar complications? Patellar complications are associated with valgus, obesity, lateral retinacular release, and a thin patella. Selecting a prosthetic trochlea that will ensure proper patellar tracking is important. Resurfacing is an option if patellar thickness is greater than 12mm. (2) What is the best management of patellar fracture? The answer depends on two factors: (a) is the extensor apparatus disrupted? and (b) is the patellar implant loose? When either factor is present, revision surgery is needed (extensor apparatus reconstruction, prosthetic implant removal). When neither factor is present, non-operative treatment is the rule. (3) What is the best management of patellar instability? Rotational malalignment should be sought. In the event of femoral and/or tibial rotational malalignment, revision surgery should be considered. If not performed, options consist of medial patello-femoral ligament reconstruction and/or medialization tibial tuberosity osteotomy. (4) What is the best management of patellar clunk syndrome? When physiotherapy fails, arthroscopic resection can be considered. Recurrence can be treated by open resection, despite the higher risk of complications with this method. (5) What is the best management of anterior knee pain? The patient should be evaluated for causes amenable to treatment (fracture, instability, clunk, osteonecrosis, bony impingement on the prosthetic trochlea). If patellar resurfacing was performed, loosening should be considered. Otherwise, secondary resurfacing is appropriate only after convincingly ruling out other causes of pain. A painstaking evaluation is mandatory before repeat surgery for anterior knee pain: surgery is not in order in the 10% to 15% of cases that have no identifiable explanation. (6) What can be done to treat patellar defects? Available options include re-implantation (with bone grafting, cement, a biconvex implant, or a metallic frame), bone grafting without re-implantation, patellar reconstruction, patellectomy (best avoided due to the resulting loss of strength), osteotomy, and extensor apparatus allograft reconstruction. LEVEL OF EVIDENCE: V, expert opinion.

Bloodpool SPECT as part of bone SPECT/CT in painful total knee arthroplasty (TKA): validation and potential biomarker of prosthesis biomechanics

PURPOSE

To compare bloodpool SPECT with planar imaging in bone SPECT/CT of painful total knee arthroplasty (TKA) with respect to inter-rater agreement, confidence, prosthesis outcome, and biomechanical functioning.

METHODS

Retrospective study of bloodpool SPECT and planar control images. Four raters used the validated Bruderholz scheme and a 5-point scale to grade uptake. Inter-rater agreement and overall confidence scores were calculated. Variable cluster analysis was performed to identify patterns of uptake, and associations between patterns and prosthesis outcome and biomechanical functioning were examined.

RESULTS

In all, 55 knees in 43 patients were analyzed (median follow-up 17 months; revision rate 21.8%). SPECT significantly improved inter-rater agreement in 24% of regions (all P < 0.05) and overall confidence by 20% (P < 0.001). Regional uptake cluster analysis showed improved antero-posterior separation with SPECT, and distinct patterns associated with prosthesis survival in lateral femoral (P = 0.041) and medial tibial (P < 0.001) regions. The prognostic value of SPECT outperformed planar imaging for tibial (P < 0.001), patellar (P = 0.009), and synovial (P = 0.040) assessment. Internal femoral malrotation resulted in increased uptake in posteromedial (P = 0.042) and anterolateral (P = 0.016) femoral, and lateral patellar (P = 0.011) regions. Internal tibial malrotation increased uptake in posterolateral (P = 0.026) and posteromedial tibial (P = 0.005), and medial patellar regions (P = 0.004). Bloodpool SPECT improved the prognostic value of late-phase SPECT/CT for the assessment of the medial tibial region.

CONCLUSIONS

Bloodpool SPECT outperforms planar assessment of painful TKAs and the identification of distinct uptake patterns make it a potentially clinically relevant biomarker of prosthesis survival and biomechanical functioning.

Significant increase of pathogen detection rate by dry arthroscopic biopsies at suspected low-grade infection following total knee arthroplasty: a prospective observational study

INTRODUCTION

The differentiation between stiff-knee and low-grade periprosthetic joint infection (PJI) is the current diagnostic challenge in total knee (TKA) revision arthroplasty. The aim of this study was to investigate the additional value of dry biopsies, compared to wet biopsies, in patients presenting with knee stiffness following primary TKA.

MATERIALS AND METHODS

Single center, prospective observational study. Consecutive patients with joint stiffness of unknown origin following primary TKA were enrolled. Patient assessment followed the diagnostic standard algorithm. During diagnostic arthroscopy, synovial fluid (synovial WBC, PMN%) and five dry biopsies (dry) were collected. Then fluid was infused and another five microbiology (wet) and five histological biopsies gathered, all from identical locations. The primary outcome parameter was the difference between the pathogens in wet and dry biopsies.

RESULTS

71 patients (61% females, 67 ± 10 years) were eligible. Preoperative blood serology mean CRP (0.7 ± 1.5 mg/dl; p = 0.852), WBC (6.6 ± 1.7 G/l; p = 0.056), and synovial fluid mean WBC (1639 ± 2111; p = 0.602), PMN% (38 ± 28; p = 0.738) did not differ between patients with negative, positive wet or dry biopsies. The histology was in 11% positive (p = 0.058). In 32% at least one pathogen was detected, 48% from wet, 44% from dry biopsies. An inhomogeneous distribution was found. Cutibacterium acnes (100%) was solely found in wet, Micrococcus luteus (75%), Staphylococcus capitis (67%), and Micrococcus lylae (100%) were predominantly found in dry biopsies. Additional dry biopsies increased the pathogen detection rate by 49%.

CONCLUSION

The addition of dry biopsies to the current standard diagnostic algorithm for PJI increased the pathogen detection rate by 49%.

Chronic pain after total knee arthroplasty

Despite a good outcome for many patients, approximately 20% of patients experience chronic pain after total knee arthroplasty (TKA).

Chronic pain after TKA can affect all dimensions of health-related quality of life, and is associated with functional limitations, pain-related distress, depression, poorer general health and social isolation.

In both clinical and research settings, the approach to assessing chronic pain after TKA needs to be in-depth and multidimensional to understand the characteristics and impact of this pain. Assessment of this pain has been inadequate in the past, but there are encouraging trends for increased use of validated patient-reported outcome measures.

Risk factors for chronic pain after TKA can be considered as those present before surgery, intraoperatively or in the acute postoperative period. Knowledge of risk factors is important to guide the development of interventions and to help to target care. Evaluations of preoperative interventions which optimize pain management and general health around the time of surgery are needed.

The causes of chronic pain after TKA are not yet fully understood, although research interest is growing and it is evident that this pain has a multifactorial aetiology, with a wide range of possible biological, surgical and psychosocial factors that can influence pain outcomes.

Treatment of chronic pain after TKA is challenging, and evaluation of combined treatments and individually targeted treatments matched to patient characteristics is advocated. To ensure that optimal care is provided to patients, the clinical- and cost-effectiveness of multidisciplinary and individualized interventions should be evaluated.

Cite this article: EFORT Open Rev 2018;3:461-470. DOI: 10.1302/2058-5241.3.180004

Patch Testing for Evaluation of Hypersensitivity to Implanted Metal Devices: A Perspective From the American Contact Dermatitis Society

The American Contact Dermatitis Society recognizes the interest in the evaluation and management of metal hypersensitivity reactions. Given the paucity of robust evidence with which to guide our practices, we provide reasonable evidence and expert opinion-based guidelines for clinicians with regard to metal hypersensitivity reaction testing and patient management. Routine preoperative evaluation in individuals with no history of adverse cutaneous reactions to metals or history of previous implant-related adverse events is not necessary. Patients with a clear self-reported history of metal reactions should be evaluated by patch testing before device implant. Patch testing is only 1 element in the assessment of causation in those with postimplantation morbidity. Metal exposure from the implanted device can cause sensitization, but a positive metal test does not prove symptom causality. The decision to replace an implanted device must include an assessment of all clinical factors and a thorough risk-benefit analysis by the treating physician(s) and patient.

Performance Comparison of Single-Radius Versus Multiple-Curve Femoral Component in Total Knee Arthroplasty: A Prospective, Randomized Study Using the Lower Quarter Y-Balance Test

Midflexion stability after total knee arthroplasty (TKA) is dependent, in part, on implant design. Midflexion performance of a single-radius (SR) design and a multi-radius, or J-curve (JC), design were compared using the Lower Quarter Y-Balance Test (YBT-LQ). Patient-reported outcomes and measures of physical performance were also compared. The authors hypothesized that the SR design would provide superior midflexion stability and, therefore, a greater reach distance in the YBT-LQ when compared with the JC design. Patients undergoing primary, unilateral TKA were prospectively enrolled and block randomized to receive either the SR (n=30) or the JC (n=30) implant. Patients reported outcome measures (Knee Injury and Osteoarthritis Outcome Score, Knee Society Score, and University of California at Los Angeles Activity Score), performed the YBT-LQ, and completed physical performance measures (walking speed, timed up-and-go test, and sit-to-stand test) before surgery and 1 year postoperatively. One year postoperatively, 40 patients (20 SR, 20 JC) were available for analysis. There were no significant differences between the groups regarding age, sex, body mass index, American Society of Anesthesiologists score, YBT-LQ results, or any other variable of interest. In both groups, significant improvements were observed for all variables of interest when compared from preoperatively to 1 year postoperatively. Implant type did not affect patient-reported or physical performance outcomes following TKA; however, patients showed significant improvement in most outcome measures by 1 year postoperatively. The significant limitations in strength and balance in this cohort of patients likely outweigh any subtle differences in implant design. [Orthopedics. 2017; 40(6):e1074-e1080.].

Evaluation of a multimodal pain therapy concept for chronic pain after total knee arthroplasty: a pilot study in 21 patients

Background

In spite of the improvement of many aspects around Total knee arthroplasty (TKA), there is still a group of 10% to 34% of patients who is not satisfied with the outcome. The therapy of chronic pain after TKA remains a medical challenge that requires an interdisciplinary therapy concept. The aim of this prospective pilot study was to evaluate the efficacy of a multimodal pain therapy in chronic complaints after TKA.

Methods

In a prospective cohort pilot study, we included patients with chronic pain after TKA who obtained in-patient care, especially multimodal pain therapy (MMPT), for at least 10 days. Essential elements of this therapy concept were physiotherapy, pain medication therapy, topical application of ketamine, local infiltration and Traditional Chinese Medicine. Patients with varying causes of complaints were excluded in advance. Before the start of the study all test persons were informed and gave their written consent. Moreover, each patient was examined and questioned at hospital admission, discharge and at its first as well as second follow-up. Additionally, knee joint mobility and stability were investigated at all examination times.

Results

From 03/07/2016 to 07/14/2016, 21 patients were included in the pilot study. 52% of the considered population were female (11 persons). The median age was 65 years (45–79 years) and the median stay in hospital amounted 9 days (8–14 days). The first follow-up was scheduled after six weeks (median: 38 days, 30–112 days) and the second one after six months (median: 8 months, 7–12 months). The number of patients of the first follow-up was 17 out of 21 (19% drop out). The drop out of the last follow-up accounted for 33%. All patients benefit from the presented applications and therapies with regard to pain, function and range of motion. Especially, during the period of in-patient treatment, nearly all patients have improved in all terms. However, during the first follow-up clear deteriorations occurred in all areas, which stagnated up to the second follow-up. The range of motion has even worsened slightly.

Conclusions

With the presented pilot study on multimodal in-patient therapy of chronic complaints due to TKA, the improvement of pain, function and mobility could be verified, especially during the stationary stay. Even though the results deteriorate during the follow-up period, they did never relapse to their initial level. In order to ensure an effective treatment, a clear diagnostic algorithm is essential, by which treatable causes, such as low-grade infections or loosenings, are safely excluded. Further prospective studies are necessary to obtain precise statements on prospects of success of our therapy plan.

Have the Causes of Revision for Total and Unicompartmental Knee Arthroplasties Changed During the Past Two Decades?

BACKGROUND

Revisions after knee arthroplasty are expected to increase, and the epidemiology of failure mechanisms is changing as new implants, technology, and surgical techniques evolve.

QUESTIONS/PURPOSES

(1) Was there improvement in survival for TKA and unicompartmental knee arthroplasty (UKA) when comparing two consecutive 11-year periods with similar followups in a national registry? (2) Were there changes in the causes of revision during the two times? (3) Could the changes in revision causes be attributed to patient or implant characteristics?

METHODS

A total of 60,623 TKAs (2426 revisions) and 7648 UKAs (725 revisions) were selected from the Norwegian Arthroplasty Register and analyzed based on year of primary surgery: 1994 to 2004 (Period 1) and 2005 to 2015 (Period 2). TKAs had median followup of 3.5 years in Period 1 and 4.2 years in Period 2. Median followup for UKAs was 2.7 years in Period 1 and 4.6 years in Period 2. Of the patients included in the registry, 99.6% were accounted for at the time of analysis, whereas 0.4% had moved abroad. We used Kaplan-Meier analyses and log-rank test to investigate changes in survival. Relative risk of revision in Period 2 relative to Period 1 was calculated for each registered revision cause in a Cox regression model adjusted for age, sex, diagnosis, fixation, and patella resurfacing.

RESULTS

For TKAs, the 10-year Kaplan-Meier survival free from revision improved from Period 1 to Period 2 from 91% (95% CI, 90%-92%) to 94% (95% CI, 94%-95%; p < 0.001). Revisions resulting from aseptic loosening of the femoral component, polyethylene wear/breakage, patellar dislocation, and unexplained pain decreased, whereas revisions resulting from early infection increased. Patients in Period 2 were younger and more often men compared with patients in Period 1. A higher risk of revision was found for male sex (relative risk [RR], 1.1; 95% CI, 1.0-1.2; p = 0.048) and age younger than 65 years (RR, 1.7; 95% CI, 1.6-1.9; p < 0.001). With UKAs, the 10-year survival free from revision was 80% (95% CI, 76%-84%) in Period 1 and 81% (95% CI, 79%-83%; p = 0.261) in Period 2. Revisions resulting from tibial aseptic loosening, polyethylene wear/breakage, and periprosthetic fractures decreased, but there were more revisions resulting from progression of osteoarthritis. In Period 2, there were more men and the average age was younger than for patients in Period 1. For UKAs, age younger than 65 years had a higher risk of revision (RR, 1.7; 95% CI, 1.5-2.0; p < 0.001), whereas sex did not affect the risk of revision.

CONCLUSIONS

We found an improvement in survival free from revision for TKA in the last period, but no similar improvement for UKA, and the survivorship for UKAs remains rather dramatically lower than that observed for TKAs. The decision to perform a UKA should be made with the explicit awareness that its survivorship is substantially inferior to that of TKA; any perceived advantages of UKA should be balanced against this issue of its decreased durability.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Metal Hypersensitivity Reactions to Orthopedic Implants

Total hip and knee replacement surgery using metal alloy devices is common. Type IV allergic reactions to these implants occur, though infrequently. While uncommon, peri-implant metal allergic reactions may cause significant morbidity for the affected individual-including aseptic loosening, pseudotumor formation and frank device failure. It is challenging to predict who will have these reactions, even in those with established pre-implant metal allergy. At this time, the scientific literature clearly supports few conclusions. Despite this, we believe several conclusions can be made: routine pre-implant testing in asymptomatic individuals is not indicated; listen to patient's concerns about metal allergy if the concern arises; patch testing is probably the best pre- and post-implant screening test; post-implantation testing is controversial and even positive LTT or patch test does not definitively diagnose morbidity from a metal allergy; and complete recovery following revision placement of an immunologically inert device is diagnostic. More research is needed to scientifically approach this issue.