Acta Orthopaedica, owned by the Nordic Orthopaedic Federation, is a non-profit electronic, immediate Open Access journal, meaning your work is free for every-one to access online as soon as it’s published (Gold OA). The journal presents articles, from all parts of the world, of basic research interest, as well as clinical studies in the field of orthopedics and related subdisciplines
Background and purpose: Although nonoperative treatment of Achilles tendon rupture (ATR) has become increasingly common, the optimal duration of immobilization and early functional rehabilitation remains uncertain. We aimed to compare outcomes of 8-week and 6-week nonoperative treatment protocols for ATR, with particular focus on re-rupture rates and treatment failure requiring surgery.
Methods: This register study included all university hospital-treated ATRs in the Northern Savo region, Finland, between 2014 and 2023. Patients were identified using ICD-10 and NOMESCO procedure codes. We compared outcomes between an 8-week nonoperative treatment protocol used in 2014–2018 and a 6-week protocol used in 2019–2023. Outcomes included patient demographics, treatment distribution, indications for surgery, and complications.
Results: Among 479 ATRs, 429/479 (90%) were treated nonoperatively. Operative treatment was mainly done in athletes. Operative treatment was performed in 32/251 (13%) patients in the 8-week protocol group and in 18/228 (7.9%) patients in the 6-week protocol group. Re-rupture rates were similar between the 8-week and 6-week protocols (7/251 [2.8%] vs 4/228 [1.8%] absolute risk difference −1.0 percentage point, 95% confidence interval −3.7 to 1.6). Operative treatment was mainly indicated for athletes, chronic ruptures, and re-ruptures, with a postoperative complication rate of 14%.
Conclusion: Outcomes regarding re-rupture and treatment failure following the 6-week nonoperative protocol were comparable to those observed with the 8-week protocol However, larger comparative studies in more diverse populations are needed to confirm the generalizability of these findings.
Background and purpose: Only scattered knowledge is available on when patients resume driving following surgery. We primarily aimed to investigate the timing of driving resumption and secondarily to investigate the influence of patients’ and surgical factors after fast-track hip and knee arthroplasty.
Methods: This prospective cohort study included patients undergoing primary total hip arthroplasty (THA), total knee arthroplasty (TKA), and medial unicompartmental knee arthroplasty (mUKA) in a fast-track setup at Odense University Hospital, Denmark, from September 2022 to July 2023. Eligible patients received a survey 3 to 12 months post-discharge, regarding timing of driving resumption.
Results: 408 patients received the survey with a response rate of 88%. Within 2 weeks postoperatively, 13% (95% confidence interval [CI] 8–20) of THA, 11% (CI 6–19) of TKA, and 28% (CI 18–40) of mUKA resumed driving, which increased to 77% (CI 69–84) of THA, 65% (CI 55–74) of TKA, and 80% (CI 68–88) of mUKA by week 6. Median time to driving resumption was 6 weeks for THA and TKA, and 4 weeks for mUKA. The overall median time to resume driving was shorter for patients who underwent surgery on the left leg (4 weeks) than those who underwent surgery on the right leg (6 weeks). Female patients had a higher odds ratio of delayed (> 6 weeks) driving resumption (OR 3, CI 2–5).
Conclusion: Overall, 65–80% of patients resumed driving within 6 weeks with median time being shorter (4 weeks) among mUKA patients and patients who underwent surgery on the left leg. Female sex was associated with delayed resumption of car driving beyond 6 weeks postoperatively
Background and purpose: Lateral knee replacement is not commonly performed. Possible explanations are the lower incidence of lateral knee osteoarthritis, relative technical complexity, and different biomechanics, which may affect failure modes and survival rates. We aimed to analyze the difference in risk of revision between lateral and total knee replacements (TKRs) using the Dutch Arthroplasty Register data.
Methods: From 2007 to 2021, procedures were selected from the Dutch Arthroplasty Register. Unique patients based on their first procedure were identified. Procedures performed between 2014 and 2021 were analyzed separately because BMI and Charnley score were collected from 2014 onwards. We used ATT (Average Treatment effect on the Treated) weights based on the propensity score to estimate the average treatment effect in the lateral knee replacement group. The endpoint was revision, censored for death. Kaplan–Meier survival analyses were performed in propensity-based ATT-weighted cohorts of lateral knee replacement and TKR patients. Weighted univariable Cox regression models were used to estimate revision hazard ratios (HR).
Results: In the total cohort, 847 lateral knee replacements and 240,047 TKR patients were included. In the subgroup, 560 lateral knee replacements and 155,621 TKR patients were included. The risk of revision in both the total cohort and the subgroup was higher for lateral knee replacements compared with TKRs with an ATT-adjusted HR for the total cohort of 2.15 (95% confidence interval [CI] 1.74–2.64, P < 0.001) and for the subgroup an ATT-adjusted HR of 1.55 (CI 1.08–2.21, P = 0.02). Comparison of these ATT-weighted effects with the conditional effect estimates from a regular multivariable Cox proportional hazards regression did not show large differences in this study.
Conclusion: This study showed a significantly higher risk of revision for lateral knee replacements compared with TKRs.
Background and purpose: Radiostereometric analysis (RSA) is the gold standard for assessing implant migration, with 1-year migration thresholds predicting later revision. While inducible displacement under immediate load may enable single-session functional stability assessment, no established threshold exists. We systematically reviewed RSA-measured inducible displacement after primary knee arthroplasty to determine whether a threshold identifying at-risk implants can be derived from the existing literature, and to characterize responses to loading, differences between fixation methods, temporal patterns, and the relationship to migration.
Methods: We searched PubMed, Web of Science, Scopus, and Embase (April 2025) for studies reporting in vivo RSA-measured inducible displacement after primary knee arthroplasty, requiring quantitative data with specified reference and load conditions. Studies were evaluated for links between inducible displacement and supine, non-weightbearing migration. We assessed bias risk using RoB 2 and ROBINS-E. Due to high heterogeneity, a descriptive synthesis was performed; meta-analysis and regression were not feasible (PROSPERO CRD420251043748).
Results: 23 studies were included. The most common outcome was maximum total point motion (MTPM) during supine-to-single-leg weightbearing (SLWB). Cemented tibial components tended to show greater displacement than cementless designs. Rotatory stress tests produced the largest absolute displacements; differences within the same study from SLWB were minimal. Predictive evidence remained limited.
Conclusion: Inducible displacement may indicate functional stability. The existing literature provides no threshold to identify at-risk implants and reporting was too heterogeneous to support a cut-off value. SLWB was the most common protocol. Prospective studies with standardized protocols and clinical endpoints are necessary.
Background and purpose: Clinical outcomes are well described after hip arthroscopy (HA), but less is known about the demographic, socioeconomic, and work-related characteristics of individuals undergoing the procedure at a population level. We aimed to describe demographic, socioeconomic, and regional characteristics of individuals undergoing HA in Sweden based on nationwide registry data compared with an age- and sex-matched reference population, and to describe regional variation in the annual incidence of HA using nationwide registry data.
Methods: We conducted a nationwide descriptive registry study including all individuals aged 18–65 years who underwent HA in Sweden between 2006 and 2018. Each individual was matched by sex and year of birth to 5 reference individuals from the general population. National registers provided information on demographics, region of residence, education, citizenship, employment status, income, and compensated sick leave.
Results: The study included 4,633 individuals undergoing HA and 23,060 matched reference individuals. Mean age was 36 years, and 3,019/4,633 (65%) were men. Residence-based HA incidence was highest in metropolitan and nearby counties. Individuals undergoing HA more often had post-secondary education (1,874/4,633 [40%] vs 8,003/23,060 [35%]), employment before surgery (4,299/4,633 [93%] vs 19,267/23,060 [84%]), and high-income levels (1,996/4,633 [43%] vs 7,358/23,060 [32%]) than the reference population. Compensated sick leave was more common among individuals undergoing HA both before surgery (741/4,633 [16%] vs 1,614/23,060 [7%]) and during the year after surgery (1,436/4,633 [31%] vs 1,845/23,060 [8%]).
Conclusion: Individuals undergoing HA were more often employed and belonged to higher-income groups than a matched reference population. HA incidence varied substantially between regions, and individuals undergoing HA demonstrated higher levels of compensated sick leave both before and after surgery.
Background and purpose: Although hip dysplasia is a risk factor for osteoarthritis (OA), its natural progression in adults remains poorly understood. In a longitudinal observational study, we aimed to estimate differences in OA incidence, time to OA, and minimum joint space width (JSW) between dysplastic hips and contralateral non-dysplastic hips.
Methods: Adults aged 20–70 years who underwent pelvic radiographs in Malmö, Sweden, during 2007–2008 were included. Inclusion criteria were unilateral hip dysplasia (lateral center edge angle ≤ 20°), no OA at baseline, and available follow-up imaging of both hips. OA incidence was assessed using last available follow-up imaging, whereas minimum JSW was measured bilaterally on the last available radiograph of native hips.
Results: 50 participants (median age 47 years, IQR 39–62, 36 women) were included, with median follow-up 12.5 years (IQR 7.8–14.7). OA developed in 19/50 dysplastic hips and 16/50 non-dysplastic hips, corresponding to a paired risk difference of 6 percentage points (95% confidence interval [CI] –7 to 20). Mean time to OA was 8.2 years (SD 5.2) for dysplastic hips and 9.6 years (SD 5.1) for non-dysplastic hips (mean difference –1.2 years, CI –4.8 to 2.4). Minimum JSW at follow-up was 3.3 mm (SD 1.3) in dysplastic hips and 3.5 mm (SD 0.9) in non-dysplastic hips (mean difference –0.2 mm, CI – 0.6 to 0.2).
Conclusion: No clear differences were observed in OA incidence, time to OA, or minimum JSW between dysplastic and contralateral non-dysplastic hips.
Background and purpose: Several European countries offer nationwide prenatal ultrasound screening for fetal anomalies. Few studies have examined prenatal detection of upper limb anomalies, and existing reports originate exclusively from high‑volume centers outside Europe. We aimed to assess the timing of diagnosis in patients with all Oberg–Manske–Tonkin diagnoses except tumorous dysplasias referred to the largest specialized unit in Norway, investigate prenatal detection rates, and explore associations between patient‑ and hospital‑related factors and prenatal detection.
Methods: We extracted data on timing of diagnosis according to Oberg–Manske–Tonkin phenotype, and patient- and hospital-related variables from the CULA (congenital upper limb anomaly) North Oslo Registry from 2018 to 2025. For patients with anomalies detected prenatally or at birth, we analyzed associations between patient- and hospital-related factors and prenatal detection rate by multivariable logistic regression.
Results: 703 consecutive patients were enrolled. 402 (57%) patients had their anomaly detected at birth and 252 (36%) later in life. Prenatal ultrasonography detected the upper limb anomaly in 49 (7.0%) of the patients. Among 426 patients with anomalies visible at birth whose mothers had at least 1 prenatal ultrasound scan, the examination detected the anomaly in 49 (12%). Among phenotypes observed in more than 5 patients, congenital contractures (amyoplasia, distal arthrogryposis), reduction deficiencies (transverse, radial, ulnar), and ulnar polydactyly had the highest detection rates. Prenatally detected cases were more often born in university hospitals and more frequently had bilateral upper limb involvement and/or associated anomalies than those diagnosed at birth.
Conclusion: 7.0% of the upper limb anomalies were detected prenatally, 57% at birth, and 36% later in life. Prenatal detection rates were lower than those reported from larger non-European hand units, likely due to the inclusion of all upper limb anomaly diagnoses in this study and Norway’s decentralized prenatal care system.
Background and purpose: Bicruciate-retaining (BCR) total knee arthroplasty (TKA) aims to restore physiological knee kinematics and joint stability by preserving both cruciate ligaments, potentially improving patient satisfaction. However, long-term clinical outcomes and tibial component migration remain insufficiently understood. We therefore aimed to evaluate long-term implant fixation and clinical outcome after BCR-TKA compared with cruciate-retaining (CR) TKA.
Methods: We performed a long-term follow-up of a randomized controlled trial using radiostereometric analysis (RSA) to compare tibial implant migration between BCR-TKA and CR-TKA. The primary outcome was maximum total point motion (MTPM) of the tibial component, measured with model-based RSA at 3 months, 1, 2, 5, and 10 years. Secondary outcomes included the Oxford Knee Score (OKS) and Forgotten Joint Score (FJS) at identical time points. Mortality, reoperations, and revisions were recorded.
Results: 25 patients were included in each group. At 10 years, the estimated mean MTPM was 0.88 mm (95% confidence interval [CI] 0.64–1.12) in the BCR group and 0.64 mm (CI 0.40–0.88) in the CR group (between-group difference −0.23 mm, CI −0.57 to 0.10). Estimated changes in OKS and FJS showed no evidence of differing longitudinal trajectories between groups. 2 revisions occurred in the BCR group, whereas none occurred in the CR group.
Conclusion: No significant differences were detected between BCR-TKA and CR-TKA in tibial implant migration or patient-reported outcomes over the 10-year follow-up. In contrast, the incidence of complications was higher in the BCR group, indicating that careful patient selection and optimization of surgical strategies remain important for BCR-TKA.
Background and purpose: Routine removal of elastic stable intramedullary nails (ESIN) after pediatric diaphyseal forearm fractures remains common practice despite limited supporting evidence. We aimed to evaluate refracture risk following ESIN retention compared with implant removal and assessed complications and healthcare resource use.
Methods: In this retrospective cohort study, patients treated with ESIN for diaphyseal forearm fractures at a single center were included. Following a policy change, routine implant removal was discontinued in favor of retaining implants unless symptomatic. Patients were grouped into removal and non-removal. The primary outcome was refracture, analyzed using Cox regression, and early refractures (< 12 months), using logistic regression. Secondary outcomes included complications and healthcare resource utilization (outpatient visits, radiographic examinations during follow-up).
Results: 288 patients were included, of whom 136 underwent implant removal and 152 retained their implants. Among patients with implant retention, 9/152 (5.9%) subsequently required removal, most commonly due to implant-related irritation. Refracture occurred in 13/136 (9.6%) after implant removal and 8/152 (5.3%) after implant retention (absolute risk difference 4.3 percentage points, 95% confidence interval [CI] −1.8 to 10.4; HR 1.4, CI 0.5–3.4). Early refracture occurred in 8/136 (5.9%) patients after implant removal and 5/152 (3.3%) after implant retention (absolute risk difference 2.6 percentage points, CI −2.3 to 7.5; OR 1.8, CI 0.6–6.2), including 3 cases within 6 months after removal. Complications occurred in 11/136 (8.1%) patients after implant removal. Infection occurred in 5/136 (3.7%) after implant removal vs 4/288 (1.4%) after the initial surgery (risk difference 2.3 percentage points, CI −1.2 to 5.7).
Conclusion: ESIN retention was well tolerated and associated with reduced healthcare utilization. No clear difference in refracture risk was observed between groups, although the study was not powered to detect moderate differences in risk.
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