MRI of complex regional pain syndrome in the foot.

PURPOSE: To evaluate the diagnostic potential of MRI in patients with suspected CRPS (complex regional pain syndrome). METHOD: A retrospective health-record search was conducted for patients with suspected CRPS (foot). Fifty patients with initially suspected CRPS were included (37 females (51 ± 13 years) and 13 males (44 ± 15 years)). All patients underwent MRI. Two radiologists assessed skin, bone, and soft tissue parameters on MRI. The final diagnosis was CRPS (Gold standard: Budapest criteria) or non-CRPS. MRI parameters were compared between CRPS patients and non-CRPS patients. RESULTS: CRPS was diagnosed in 22/50(44 %) patients. Skin thickness (1.9 ± 0.5 mm vs. 1.7 ± 0.3 mm, p = 0.399), enhancement, and subcutaneous edema showed no differences between CRPS and non-CRPS patients. Bone marrow edema presence and pattern were not different between groups. Up to 50 % of CRPS patients showed no bone marrow edema. Subcortical enhancement and periosteal enhancement were not different between groups. For reader 1, muscle edema score was higher in the non-CRPS group compared to the CRPS group (0.1 ± 0.2 vs. 0.6 ± 1.0, p = 0.008), but not different for reader 2 (0.1 ± 0.5 vs. 0.2 ± 0.8, p = 0.819). Perfusion pattern was more extensive in non-CRPS patients for reader 1 (p = 0.048), but not for reader 2 (p = 0.157). Joint effusions showed no difference between groups. CONCLUSIONS: MRI cannot distinguish between CRPS and non-CRPS patients. The role of MR imaging in patients with suspected CRPS is to exclude alternative diagnoses that would better explain patients' symptoms.

Anomalous insertion of the medial meniscus into a triple bundle anterior cruciate ligament: A rare combination of two anatomical variants.

Rare anatomical variants in the human knee joint include the anomalous insertion of the medial meniscus (AIMM) into the anterior cruciate ligament (ACL) or the presence of a triple bundle ACL. The functional implications of those anomalies have not yet been fully elucidated and might be important in reconstructive surgery of the damaged knee. We report the case of a 35-year-old female patient with an AIMM into a triple bundle ACL associated with tears of the medial meniscus in both of her knees. Arthroscopic partial meniscectomy was performed on one side, and conservative treatment with physiotherapy was chosen for the other side with good clinical outcomes.

Magnetic resonance imaging (MRI) versus single photon emission computed tomography (SPECT/CT) in painful total hip arthroplasty: a comparative multi-institutional analysis.

OBJECTIVE: To investigate the value of MRI in comparison to single photon emission computed tomography (SPECT)/CT in patients with painful hip arthroplasties. METHODS: A prospective, multi-institutional study was performed. Therefore, 35 consecutive patients (21 female, 14 male, mean age 61.8 ± 13.3 years) with 37-painful hip arthroplasties were included. A hip surgeon noted the most likely diagnosis based on clinical examination and hip radiographs. Then, MRI and SPECT/CT of the painful hips were acquired. MRI and SPECT/CT were assessed for loosening, infection, fracture, tendon pathology and other abnormalities. Final diagnosis and therapy was established by the hip surgeon after integration of MRI and SPECT/CT results. The value of MRI and SPECT/CT for diagnosis was assessed with a 3-point scale (1 = unimportant, 2 = helpful, 3 = essential). RESULTS: Loosening was observed in 13/37 arthroplasties (6 shaft only, 6 cup only, 1 combined). Sensitivity, specificity, positive predictive value and negative predictive value for loosening of MRI were 86%/88%/60%/100% and of SPECT/CT 93%/97%/90%/100%, respectively. MRI and SPECT/CT diagnosed infection correctly in two of three patients and fractures in two patients, which were missed by X-ray. MRI detected soft tissue abnormalities in 21 patients (6 bursitis, 14 tendon lesions, 1 pseudotumor), of which only 1 tendon abnormality was accurately detected with SPECT/CT. All 5 arthroplasties with polyethylene wear were correctly diagnosed clinically and with both imaging modalities. MRI and SPECT/CT were judged as not helpful in 0/0%, as helpful in 16%/49% and essential in 84%/51%. CONCLUSION: In patients with painful hip arthroplasty SPECT/CT is slightly superior to MR in the assessment of loosening. MRI is far superior in the detection of soft tissue, especially tendon pathologies. ADVANCES IN KNOWLEDGE: To our knowledge this is the first prospective, multiinstitutional study which compares MRI with SPECT/CT in painful hip arthroplasties. We found that MRI is far superior in the detection of soft tissue pathologies, whereas SPECT/CT remains slightly superior regarding loosening.

Long-Term Outcomes of Pectoralis Major Transfer for the Treatment of Irreparable Subscapularis Tears: Results After a Mean Follow-up of 20 Years.

BACKGROUND: One recognized salvage option in the treatment of an irreparable subscapularis tear is the pectoralis major tendon transfer (PMT). We aimed to analyze the long-term clinical and imaging outcome of PMT for irreparable subscapularis deficiency. METHODS: Twenty-eight consecutive patients representing 30 shoulders underwent PMT at a mean age of 53.0 years (range, 35 to 67 years). At a mean of 19.7 years (range, 18 to 22 years) postoperatively, 24 shoulders (80%) were clinically examined and 21 were radiographically and sonographically assessed. The long-term results were compared with preoperative findings and previously published short-term results. RESULTS: The mean relative Constant score (percentage of age and sex-matched normal scores; CS%) and the Subjective Shoulder Value (SSV) both improved significantly from preoperatively (CS%, 47%, and SSV, 22%) to postoperatively (CS%, 77%, and SSV, 71%; p < 0.001 for both). All patients rated their results as good or excellent. Active anterior elevation was improved from preoperatively (120°) to postoperatively (131°), but the difference was not significant. Active internal and external rotation decreased significantly from the short-term (32-month) follow-up to the time of the latest follow-up (p = 0.005 and p = 0.002, respectively); however, internal rotation remained at 6 points compared with the 8 points recorded at short-term follow-up and external rotation decreased only from a mean of 51° to 39°. Loss of active range of motion was not observed subjectively and was not subjectively limiting, represented by the high ultimate SSV and overall satisfaction. Four shoulders (19%) showed evidence of glenohumeral arthropathy (Samilson and Prieto grade 3), but clinically were mildly symptomatic to asymptomatic at the time of the latest follow-up (CS% range, 67% to 88%; SSV range, 70% to 80%). Rupture of the PMT was sonographically identified in 2 patients (10%) and was associated with radiographic evidence of advanced cuff tear arthropathy (Hamada stages ≥4). Six (20%) of the initial 30 shoulders were revised, and 1 (4%) of the 24 shoulders that were clinically examined underwent reverse total shoulder arthroplasty. CONCLUSIONS: At long-term follow-up, PMT for isolated and combined subscapularis tears is associated with good to excellent clinical results. Although one-third of the shoulders developed mildly symptomatic or asymptomatic osteoarthritis, the need for salvage with use of reverse total shoulder arthroplasty was rare. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Can quantitative sensory tests predict failed back surgery?: A prospective cohort study.

BACKGROUND: Failed back surgery syndrome (FBSS) is a pain condition refractory to therapy, and is characterised by persistent low back pain after spinal surgery. FBSS is associated with severe disability, low quality of life and high unemployment. We are currently unable to identify patients who are at risk of developing FBSS. Patients with chronic low back pain may display signs of central hypersensitivity as assessed by quantitative sensory tests (QST). This can contribute to the risk of developing persistent pain after surgery. OBJECTIVE: We tested the hypothesis that central hypersensitivity as assessed by QST predicts FBSS. DESIGN: Prospective cohort study. SETTING: Three tertiary care centres. PATIENTS: 141 patients scheduled for up to three segment spinal surgery for chronic low back pain (defined as at least 3 on a numerical rating scale on most days during the week and with a minimum duration of 3 months) due to degenerative changes. OUTCOMES: We defined FBSS as persistent pain, persistent disability or a composite outcome defined as either persistent pain or disability. The primary outcome was persistent pain 12 months after surgery. We applied 14 QST using electrical, pressure and temperature stimulation to predict FBSS and assessed the association of QST with FBSS in multivariable analyses adjusted for sociodemographic, psychological and clinical and surgery-related characteristics. RESULTS: None of the investigated 14 QST predicted FBSS, with 95% confidence intervals of crude and adjusted associations of all QST including one as a measure of no association. Results remained robust in all sensitivity and secondary analyses. CONCLUSION: The study indicates that assessment of altered central pain processing using current QST is unlikely to identify patients at risk of FBSS and is therefore unlikely to inform clinical decisions.

Guided growth with tension band plate or definitive epiphysiodesis for treatment of limb length discrepancy?

BACKGROUND: It is not exactly known whether guided growth or definitive epiphysiodesis techniques are superior in treating limb length discrepancy (LLD). The purpose of the present study was therefore to find out if definitive epiphysiodesis is associated with more powerful LLD correction than tension band plate epiphysiodesis. METHODS: Pediatric patients with LLD treated either with tension band plating as a guided growth technique (temporary epiphysiodesis) or a percutaneous drilling technique (definitive epiphysiodesis) around the knee and a minimum follow-up of 12 months were included in this retrospective study. Radiographic measurements were performed by two independent reviewers. The reduction in side difference between preoperative radiographs and last follow-up was calculated and compared between surgical techniques. RESULTS: Thirty-eight patients (mean age 13.6 years) were included, 17 treated with temporary and 21 with definitive epiphysiodesis. Average follow-up was at 578 days. The reduction of the LLD in 12 months was 5.7 mm in patients treated with temporary epiphysiodesis and 8.4 mm with definitive epiphysiodesis, respectively (p = 0.22). In both groups, LLD could be statistically significantly reduced after 12 and 24 months. Definitive epiphysiodesis had a lower revision rate (4.8% vs. 17.6%). Intra- and interobserver reliability of the measurements was excellent. CONCLUSIONS: As in earlier studies supposed, temporary epiphysiodesis with tension band plating seems to correct LLD less powerful compared to definitive percutaneous epiphysiodesis. However, in the present study, the differences of LLD correction were not statistically significant. We do not recommend the use of tension band plates for LLD correction due to inferior correction with higher complication and revision rate.

MR imaging of pubic symphysis after uncomplicated vaginal delivery and planned caesarean delivery in the first postpartum week.

PURPOSE: To compare changes in the pubic symphysis between women with vaginal delivery and women with caesarean sections within the first postpartum week. MATERIALS AND METHODS: After institutional review board approval 30 healthy women were prospectively examined with MRI (transverse STIR-sequence) three days after delivery. 17 women with vaginal delivery (mean age 33.2 ±â€¯4 years) and 13 with caesarean delivery (35.2 ±â€¯5.6 years) were compared by two musculoskeletal radiologists. Bone marrow edema (location and extent), fluid in the joint gap, joint space width and stress fractures were assessed. RESULTS: Prevalence of bone marrow edema was high and not different between groups (13/17 (76.5%) vaginal deliveries) and 10/13 (76.9% caesarean deliveries) for reader 1 (p = 0.992) and 14/17 (82.4%) and 10/13 (76.9%) for reader 2 (p = 0.762). Size of bone marrow edema was not statistically significantly different for both readers (results reader 1: right side 2.5 ±â€¯3.3 mm vs. 6.3 ±â€¯7.3 mm, p = 0.300; left side 3.4 ±â€¯4.1 mm vs. 4.1 ±â€¯4.6 mm, p = 0.837). Fluid in the joint was seen in 4/17 (23.5%) vs. 2/13 (15.4%) (p = 0.580) for reader 1 (similar for reader 2). Joint space width did not differ between groups (2.6 ±â€¯0.7 mm vs. 3.1 ±â€¯1.2 mm, p = 0.198). Pubic symphysis diastasis (joint space width > 10 mm) was not observed. Interreader agreement for these parameters was substantial to almost perfect (0.671-0.984, kappa values/intraclass correlation). Reader 1 found no stress fractures, while reader 2 suspected 1 stress fracture on a right pubic bone in a woman after caesarean delivery. CONCLUSIONS: Pubic bone marrow edema is present in 3 of 4 women in the first postpartum week unrelated to the delivery mode.

Postpartum Bone Marrow Edema at the Sacroiliac Joints May Mimic Sacroiliitis of Axial Spondyloarthritis on MRI.

OBJECTIVE: The objective of our study was to compare MRI findings in the sacroiliac joints of postpartum women (as a model of mechanical changes) and women with known axial spondyloarthritis (as an inflammatory model). SUBJECTS AND METHODS: For this prospective multicenter age-matched, case-control study, sacroiliac joint MRI examinations of 30 healthy women (mean age, 34.0 years) in the early postpartum period (mechanical group) and 30 age-matched women (mean age, 33.8 years) with known axial spondyloarthritis (retrospective inflammatory group) were compared. Blinded to clinical information, readers assessed MR images using the following scoring systems: Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index, Berlin method, Assessment of Spondyloarthritis International Society (ASAS) criteria, and SPARCC MRI structural score. Descriptive statistics as percentages of the different findings (i.e., bone marrow edema [BME], erosion, fatty bone marrow replacement, backfill, ankylosis) and scores between groups and between delivery modes were compared. RESULTS: In the postpartum group, 63.3% (19/30) of women showed BME around the sacroiliac joints compared with 86.7% (26/30) of women in the spondyloarthritis group (based on ASAS criteria). Erosions were uncommon in the postpartum group (10.0% [3/30] postpartum vs 56.7% [17/30] spondyloarthritis). Fatty bone marrow replacement, backfill, and ankylosis were not seen in the postpartum group. In subjects with positive MRI findings for sacroiliitis based on ASAS criteria, the SPARCC MRI index (mean ± SD, 13.6 ± 14.5 vs 13.0 ± 10.7; p = 0.818) and Berlin method (4.5 ± 3.0 and 5.5 ± 3.5, p = 0.378) were not different between the postpartum and spondyloarthritis groups. Scores were not different between birth modalities. CONCLUSION: Pregnancy-induced BME at the sacroiliac joints, as a result of prolonged mechanical stress, was present in 63.3% of women who underwent MRI during the early postpartum period and may mimic sacroiliitis of axial spondyloarthritis.

Treatment for Symptomatic SLAP Tears in Middle-Aged Patients Comparing Repair, Biceps Tenodesis, and Nonoperative Approaches: A Cost-Effectiveness Analysis.

PURPOSE: To evaluate the cost-effectiveness of nonoperative management, primary SLAP repair, and primary biceps tenodesis for the treatment of symptomatic isolated type II SLAP tear. METHODS: A microsimulation Markov model was constructed to compare 3 strategies for middle-aged patients with symptomatic type II SLAP tears: SLAP repair, biceps tenodesis, or nonoperative management. A failed 6-month trial of nonoperative treatment was assumed. The principal outcome measure was the incremental cost-effectiveness ratio in 2017 U.S. dollars using a societal perspective over a 10-year time horizon. Treatment effectiveness was expressed in quality-adjusted life-years (QALY). Model results were compared with estimates from the published literature and were subjected to sensitivity analyses to evaluate robustness. RESULTS: Primary biceps tenodesis compared with SLAP repair conferred an increased effectiveness of 0.06 QALY with cost savings of $1,766. Compared with nonoperative treatment, both biceps tenodesis and SLAP repair were cost-effective (incremental cost-effectiveness ratio values of $3,344/QALY gained and $4,289/QALY gained, respectively). Sensitivity analysis showed that biceps tenodesis was the preferred strategy in most simulations (52%); however, for SLAP repair to become cost-effective over biceps tenodesis, its probability of failure would have to be lower than 2.7% or the cost of biceps tenodesis would have to be higher than $14,644. CONCLUSIONS: When compared with primary SLAP repair and nonoperative treatment, primary biceps tenodesis is the most cost-effective treatment strategy for type II SLAP tears in middle-aged patients. Primary biceps tenodesis offers increased effectiveness when compared with both primary SLAP repair and nonoperative treatment and lower costs than primary SLAP repair. LEVEL OF EVIDENCE: Level III, economic decision analysis.

Cost-effectiveness of Virtual Bone Strength Testing in Osteoporosis Screening Programs for Postmenopausal Women in the United States.

Purpose To investigate whether assessment of bone strength with quantitative computed tomography (CT) in combination with dual-energy x-ray absorptiometry (DXA) is cost-effective as a screening tool for osteoporosis in postmenopausal women. Materials and Methods A state-transition microsimulation model of osteoporosis for postmenopausal women aged 55 years or older was developed with a lifetime horizon and U.S. societal perspective. All model inputs were derived from published literature. Three strategies were compared: no screening, DXA with T score-dependent rescreening intervals, and a combination of DXA and quantitative CT with different intervals (3, 5, and 10 years) at different screening initiation ages (55-65 years). Oral bisphosphonate therapy was started if DXA hip T scores were less than or equal to -2.5, 10-year risk for hip fracture was greater than 3% (World Health Organization Fracture Risk Assessment Tool score, or FRAX), 10-year risk for major osteoporotic fracture was greater than 20% (FRAX), quantitative CT femur bone strength was less than 3000 N, or occurrence of first fracture (eg, hip, vertebral body, wrist). Outcome measures were incremental cost-effectiveness ratios (ICERs) in 2015 U.S. dollars per quality-adjusted life year (QALY) gained and number of fragility fractures. Probabilistic sensitivity analysis was also performed. Results The most cost-effective strategy was combined DXA and quantitative CT screening starting at age 55 with quantitative CT screening every 5 years (ICER, $2000 per QALY). With this strategy, 12.8% of postmenopausal women sustained hip fractures in their remaining life (no screening, 18.7%; DXA screening, 15.8%). The corresponding percentages of vertebral fractures for DXA and quantitative CT with a 5-year interval, was 7.5%; no screening, 11.1%; DXA screening, 9%; for wrist fractures, 14%, 17.8%, and 16.4%, respectively; for other fractures, 22.6%, 30.8%, and 27.3%, respectively. In probabilistic sensitivity analysis, DXA and quantitative CT at age 55 years with quantitative CT screening every 5 years was the best strategy in more than 90% of all 1000 simulations (for thresholds of $50 000 per QALY and $100 000 per QALY). Conclusion Combined assessment of bone strength and bone mineral density is a cost-effective strategy for osteoporosis screening in postmenopausal women and has the potential to prevent a substantial number of fragility fractures. © RSNA, 2017 Online supplemental material is available for this article.

The Legend of the Luschka Tubercle and Its Association With Snapping Scapulae: Osseous Morphology of Snapping Scapulae on CT Images.

OBJECTIVE: The purpose of this article is to determine the osseous morphology of snapping scapulae on CT images. MATERIALS AND METHODS: Retrospectively, 2D and 3D CT images of the scapulae of 35 patients with snapping scapula were compared with 35 age-matched control group subjects. Two observers analyzed the following parameters: presence of the Luschka tubercle; abnormalities of the bones and periscapular soft tissues; shape, thickness, and length of the superior angle of the scapula; craniocaudal length of the scapula; minimum distance between the scapula and rib cage; depth of the subscapular fossa; and the superomedial angle. RESULTS: In patients with snapping scapulae, observer 1 did not find any Luschka tubercles, whereas observer 2 detected one; in the control group both observers found two Luschka tubercles (p > 0.49). One scapular osteochondroma was found in the group with snapping scapulae. No further abnormalities of the rib cage or periscapular soft tissues were found in that group. The superior angle of the scapula was significantly thicker in the snapping scapula group compared with the control group (4.8 ± 1.3 mm vs 4.0 ± 1.0 mm, p < 0.012). The subscapular fossa was significantly deeper in patients with snapping scapula than in control group subjects (25.7 ± 5.2 mm vs 21.8 ± 5.0 mm, p < 0.005). The remaining parameters did not differ significantly between the groups. CONCLUSION: The Luschka tubercle was rarely observed and not associated with a snapping scapula. However, the superior angle of the scapula was significantly thicker and the subscapular fossa was significantly deeper in patients with snapping scapula than in control group subjects.

Frequency of Arthritis-Like MRI Findings in the Forefeet of Healthy Volunteers Versus Patients With Symptomatic Rheumatoid Arthritis or Psoriatic Arthritis.

OBJECTIVE: The objective of the present study is to evaluate arthritis-like findings on MRI studies of the forefeet of healthy volunteers versus patients with symptomatic rheumatoid arthritis (RA) or psoriatic arthritis (PsA). MATERIALS AND METHODS: Two observers analyzed MR images of the forefeet of 31 healthy volunteers, 30 patients with symptomatic RA, and 30 patients with symptomatic PsA, to identify MRI patterns of RA or PsA (e.g., bone marrow edema [BME], erosions, tenosynovitis, joint effusion, periarticular soft-tissue edema, or bony proliferations) on the basis of the Outcome Measures in Rheumatoid Arthritis Clinical Trial RA MRI scoring system and the PsA MRI scoring system. The Mann-Whitney test with Bonferroni correction was used for statistical analysis. RESULTS: Reader 1 found BME in 14 healthy volunteers (45%), whereas reader 2 found BME in 10 volunteers (32%). Tenosynovitis was observed by reader 1 in three healthy volunteers (10%). Joint effusion was found by reader 1 in seven healthy volunteers (23%) and by reader 2 in three volunteers (10%); the mean intensity grades for these findings were low (range, 1-1.33). Erosions, soft-tissue edema, and bony proliferations were not found in the forefeet of healthy volunteers. Reader 1 and reader 2 observed all arthritis-like features on the MR images of patients with RA. The percentages of patients with RA who had such MRI features, as identified by reader 1 and reader 2, respectively, were as follows: BME, 83% and 80%; erosions, 40% and 40%; tenosynovitis, 33% and 17%; effusion, 87% and 53%; soft-tissue edema, 20% and 27%; and bony proliferations, 3% and 3%. The percentages of patients with PsA who were found to have arthritis-like findings on MR images, as determined by reader 1 and reader 2, respectively, were as follows: BME, 70% and 67%; erosions, 20% and 20%; tenosynovitis, 57% and 50%; effusion, 70% and 37%; and soft-tissue edema, 60% and 53%. Bony proliferations were observed by reader 2 only in 7% of patients with PsA. The mean minimum intensity grade was 1 (for tenosynovitis in patients with RA, as observed by reader 2), whereas the maximum intensity grade was 2.53 (for erosions in patients with RA, as observed by reader 1). Tenosynovitis and soft-tissue edema were observed more frequently in patients with PsA than in patients with RA (p = 0.001-0.059). CONCLUSION: On the forefoot of healthy volunteers, mild BME is a common finding, and tenosynovitis and joint effusion are occasional findings. The frequency and intensity of arthritis-like findings on MRI are similar in patients with RA and PsA, with the exception of tenosynovitis and soft-tissue edema, which are more frequently observed in patients with PsA than in patients with RA.

Subchondroplasty: What the Radiologist Needs to Know.

OBJECTIVE: Subchondroplasty is a novel minimally invasive procedure that is used to treat painful bone marrow lesions in patients with knee osteoarthritis or insufficiency fractures. The objective of this article is to describe the surgical technique and the pre- and postoperative imaging findings of a small case series acquired at a single center. CONCLUSION: The radiologist should be familiar with the anticipated postoperative imaging appearances after subchondroplasty and the potential complications.

Unicompartmental knee arthroplasty MRI: impact of slice-encoding for metal artefact correction MRI on image quality, findings and therapy decision.

OBJECTIVES: To evaluate the impact of slice-encoding for metal artefact correction (SEMAC) on image quality, findings, and therapy decision in patients with unicompartmental knee arthroplasty (UKA). METHODS: Forty-five painful UKAs were examined at 1.5T-MRI (STIR, proton-density(PD)-weighted sequence, each with SEMAC and high-bandwidth). Artefact size, image quality, anatomic depiction, and clinically relevant findings were compared between SEMAC and high-bandwidth (2 readers). In 30 patients, therapy decision was retrospectively assessed by two orthopaedic surgeons without MRI, with high-bandwidth-MRI, and with SEMAC-MRI. RESULTS: SEMAC reduced mean artefact size for STIR (11.8 cm(2) vs. 37.7 cm(2)) and PD (16.8 cm(2) vs. 18.9 cm(2)), p < 0.0005 for both comparisons. SEMAC showed more blurring than high-bandwidth, p < 0.0005. STIR-SEMAC revealed more bone marrow oedema (29 vs. 18 patients, p = 0.001, 30 vs. 13 patients, p < 0.0005, for reader 1 and 2 respectively). PD-SEMAC was worse in detecting meniscal lesions (6 missed, p = 0.031, 9 missed, p = 0.004, by reader 1 and 2 respectively) than PD-high-bandwidth. Revision-surgery was chosen in 12 and 11 patients without MRI (surgeon 1 and 2), with high-bandwidth-MRI in 15 and 14 patients, and with SEMAC-MRI in 19 and 14 patients. CONCLUSIONS: STIR-SEMAC was useful in detecting bone marrow oedema and influenced the orthopaedic surgeons' decisions towards surgery, while PD-SEMAC showed no clinical benefit. KEY POINTS: • Slice-encoding for metal artefact correction (SEMAC) MRI reduces metal-induced artefact size. • STIR SEMAC detects more bone marrow oedema in painful unicompartmental knee arthroplasty. • STIR SEMAC can help the orthopaedic surgeon with decision making. • PD SEMAC suffers from blurring of images, potentially masking relevant meniscal lesions. • PD SEMAC does not improve cartilage lesion detection in the non-operated compartments.