SLSverre Løken

Sverre Løken

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Previous Organizations / Institutes

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Sverre Løken has a total of 29 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    Arthroscopic Surgery Versus Sham Surgery for Femoroacetabular Impingement Syndrome and/or Labral Tears: A Double-Blind Randomized Controlled Pilot Trial (HIPARTI)

    by Kristian Marstrand Warholm, Elsie Hibbert, Eva Ageberg, Anders Pålsson, Ioannis Kostogiannis, Agnethe Nilstad, Sverre Løken, Lars Nordsletten, Joanne L. Kemp, May Arna Risberg

    Background: Femoroacetabular impingement syndrome is a common cause of hip pain in young adults. Hip arthroscopy has demonstrated substantial improvements in observational studies and several randomized trials comparing surgery with physical therapist–led treatment; however, randomized placebo-controlled trials remain scarce. Purpose/Hypothesis: The primary aim was to compare arthroscopic surgery with sham surgery on hip-related quality of life at 1 year, measured with the 33-item International Hip Outcome Tool (iHOT-33). Secondary aims were to evaluate effects on patient-reported outcomes, hip strength, range of motion, functional performance, and radiographic measures. It was hypothesized that arthroscopic surgery would yield superior iHOT-33 scores. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: Patients were randomized to arthroscopic surgery or sham surgery followed by a 3-month, physical therapist–led, postsurgical rehabilitation program. The primary outcome was the between-group difference in iHOT-33 at 1 year. Secondary outcomes included Hip disability and Osteoarthritis Outcome Score (HOOS) scores, hip range of motion, isometric hip strength, functional performance, and radiographic changes. Follow-up measurements were performed at 6 months, 1 year, and 2 years. Results: A total of 30 patients (31 hips; mean age, 30.0 ± 7.9 years; 63% male) were included. No significant differences in iHOT-33 scores were observed between the surgical and sham surgical groups at 1 year ( P = .08), or 2 years ( P = .54). Both groups showed improvements exceeding the minimal clinically important difference (MCID), with the surgical group demonstrating the greatest gains at 2 years (mean changes: 17.4 at 6 months; 21.7 at 1 year; 32.1 at 2 years). Both groups improved; HOOS Pain reached MCID earlier in the sham surgery group (6 months) and at 1 year in the surgical group, with more sustained improvement in the surgical group at 2 years. Strength and functional performance improved in both groups, but the surgical group showed greater gains in side bridge endurance and single-leg hop performance at 2 years. Radiographs confirmed normalization of alpha angle in the surgical group, with reductions in alpha angle on anteroposterior and Dunn 45º/20º views at 1-year follow-up. Conclusion: Arthroscopic surgery did not demonstrate superiority over sham surgery for iHOT-33 at any time point. Both groups improved, but the surgical group showed more consistent and clinically meaningful gains in secondary outcomes and achieved substantial radiographic cam correction. Given the limited sample size, the study was underpowered to detect between-group differences. A fully powered multicenter RCT is warranted to confirm these findings. Registration: NCT02692807 (ClinicalTrials.gov identifier).

  • Open Access

    Long-Term Outcomes of Arthroscopically Verified Focal Cartilage Lesions in the Knee

    by Thomas Birkenes, Ove Furnes, Stein Haakon Laastad Lygre, Eirik Solheim, Asbjorn Aaroen, Gunnar Knutsen, Jon Olav Drogset, Stig Heir, Lars Engebretsen, Sverre Loken, et al.

    Background: Focal cartilage lesions (FCLs) are frequently found during knee arthroscopies and may impair quality of life (QoL) significantly. Several treatment options with good short-term results are available, but the natural history without any treatment is largely unknown. The aim of this study was to evaluate patient-reported outcome measures (PROMs), the need for subsequent cartilage surgery, and the risk of treatment failure 20 years after diagnosis of an FCL in the knee. Methods: Patients undergoing any knee arthroscopy for an FCL between 1999 and 2012 in 6 major Norwegian hospitals were identified. Inclusion criteria were an arthroscopically classified FCL in the knee, patient age of ≥18 years at surgery, and any preoperative PROM. Exclusion criteria were lesions representing knee osteoarthritis or “kissing lesions” at surgery. Demographic data, later knee surgery, and PROMs were collected by questionnaire. Regression models were used to adjust for and evaluate the factors impacting the long-term PROMs and risk factors for treatment failure (defined as knee arthroplasty, osteotomy, or a Knee injury and Osteoarthritis Outcome Score-Quality of Life [KOOS QoL] subscore of 1 FCL (OR, 1.9 [CI, 1.1 to 3.3]), a full-thickness lesion (OR, 2.5 [95% CI, 1.3 to 5.0]), and a lower level of education (OR, 1.8 [95% Cl, 1.1 to 2.8]). Autologous chondrocyte implantation (ACI) was associated with significantly higher KOOS QoL, by 17.5 (95% CI, 3.2 to 31.7) points, and a lower risk of treatment failure compared with no cartilage treatment, microfracture, or mosaicplasty. Conclusions: After a mean follow-up of 19 years, patients with an FCL who did not require a subsequent knee arthroplasty had significantly higher PROM scores than preoperatively. Nonsurgical treatment of FCLs had results equal to those of the surgical FCL treatments except for ACI, which was associated with a better KOOS and lower risk of treatment failure. Full-thickness lesions, >1 FCL, a lower level of education, and a greater BMI were the main risk factors associated with poorer results. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.


  • Open Access

    Previous cartilage surgery is associated with inferior patient‐reported outcomes after knee arthroplasty

    by Thomas Birkenes, Ove Furnes, Stein Håkon Låstad Lygre, Eirik Solheim, Asbjørn Årøen, Gunnar Knutsen, Jon Olav Drogset, Stig Heir, Lars Engebretsen, Sverre Løken, et al.

    Purpose: The hypothesis of the present study assumed that a history of focal cartilage lesions would not affect Knee Injury and Osteoarthritis Outcome scores (KOOSs) following knee arthroplasty compared to a matched national cohort of knee arthroplasty patients.Methods: Fifty‐eight knee arthroplasty patients with previous surgery for focal cartilage lesions (cartilage cohort) were compared to a matched cohort of 116 knee arthroplasty patients from the Norwegian Arthroplasty Register (control group). Age, sex, primary or revision arthroplasty, type of arthroplasty (total, unicondylar or patellofemoral), year of arthroplasty surgery and arthroplasty brand were used as matching criteria. Demographic data and KOOS were obtained through questionnaires. Regression models were employed to adjust for confounding factors.Results: Mean follow‐up post knee arthroplasty surgery was 7.6 years (range 1.2–20.3) in the cartilage cohort and 8.1 (range 1.0–20.9) in the control group. The responding patients were at the time of surgery 54.3 versus 59.0 years in the cartilage and control group, respectively. At follow‐up the control group demonstrated higher adjusted Knee Injury and Osteoarthritis Outcome subscores than the previous focal cartilage patients with a mean adjusted difference (95% confidence interval in parentheses): Symptoms 8.4 (0.3, 16.4), Pain 11.8 (2.2, 21.4), Activities of daily living (ADL) 9.3 (−1.2, 18.6), Sport and recreation 8.9 (−1.6, 19.4) and Quality of Life (QoL) 10.6 (0.2, 21.1). The control group also demonstrated higher odds of reaching the patient‐acceptable symptom state threshold for the Knee Injury and Osteoarthritis Outcome subscores with odds ratio: Symptoms 2.7 (1.2, 6.4), Pain 3.0 (1.3, 7.0), ADL 2.1 (0.9, 4.6) and QoL 2.4 (1.0, 5.5).Conclusion: Previous cartilage surgery was associated with inferior patient‐reported outcomes after knee arthroplasty. These patients also exhibited significantly lower odds of reaching the patient‐acceptable symptom state threshold for the Knee Injury and Osteoarthritis Outcome subscores.Level of Evidence: Level III.


  • Open Access

    The Long-Term Risk of Knee Arthroplasty in Patients with Arthroscopically Verified Focal Cartilage Lesions

    by Thomas Birkenes, Ove Furnes, Stein Haakon Laastad Lygre, Eirik Solheim, Asbjorn Aaroen, Gunnar Knutsen, Jon Olav Drogset, Stig Heir, Lars Engebretsen, Sverre Loken, et al.

    Background: Focal cartilage lesions are common in the knee. The risk of later ipsilateral knee arthroplasty remains unknown. The purposes of the present study were to evaluate the long-term cumulative risk of knee arthroplasty after arthroscopic identification of focal cartilage lesions in the knee, to investigate the risk factors for subsequent knee arthroplasty, and to estimate the subsequent cumulative risk of knee arthroplasty compared with that in the general population. Methods: Patients who had undergone surgical treatment of focal cartilage lesions at 6 major Norwegian hospitals between 1999 and 2012 were identified. The inclusion criteria were an arthroscopically classified focal cartilage lesion in the knee, an age of ≥18 years at the time of surgery, and available preoperative patient-reported outcomes (PROMs). The exclusion criteria were osteoarthritis or “kissing lesions” at the time of surgery. Demographic data, later knee surgery, and PROMs were collected with use of a questionnaire. A Cox regression model was used to adjust for and investigate the impact of risk factors, and Kaplan-Meier analysis was performed to estimate cumulative risk. The risk of knee arthroplasty in the present cohort was compared with that in the age-matched general Norwegian population. Results: Of the 516 patients who were eligible, 322 patients (328 knees) consented to participate. The mean age at the time of the index procedure was 36.8 years, and the mean duration of follow-up was 19.8 years. The 20-year cumulative risk of knee arthroplasty in the cartilage cohort was 19.1% (95% CI, 14.6% to 23.6%). Variables that had an impact on the risk of knee arthroplasty included an ICRS grade of 3 to 4 (hazard ratio [HR], 3.1; 95% CI, 1.1 to 8.7), an age of ≥40 years at time of cartilage surgery (HR, 3.7; 95% CI, 1.8 to 7.7), a BMI of 25 to 29 kg/m2 (HR, 3.9; 95% CI, 1.7 to 9.0), a BMI of ≥30 kg/m2 (HR, 5.9; 95% CI, 2.4 to 14.3) at the time of follow-up, autologous chondrocyte implantation (ACI) at the time of the index procedure (HR, 3.4; 95% CI, 1.0 to 11.4), >1 focal cartilage lesion (HR, 2.1; 95% CI, 1.1 to 3.7), and a high preoperative visual analog scale (VAS) score for pain at the time of the index procedure (HR, 1.1; 95% CI, 1.0 to 1.1). The risk ratio of later knee arthroplasty in the cartilage cohort as compared with the age-matched general Norwegian population was 415.7 (95% CI, 168.8 to 1,023.5) in the 30 to 39-year age group. Conclusions: In the present study, we found that the 20-year cumulative risk of knee arthroplasty after a focal cartilage lesion in the knee was 19%. Deep lesions, higher age at the time of cartilage surgery, high BMI at the time of follow-up, ACI, and >1 cartilage lesion were associated with a higher risk of knee arthroplasty. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.


  • How to Avoid Complications in Hip Arthroscopy

    by Sverre Løken, Olufemi R. Ayeni

  • Open Access

    Norwegican Cartilage Project - a study protocol for a double-blinded randomized controlled trial comparing arthroscopic microfracture with arthroscopic debridement in focal cartilage defects in the knee

    by Tommy Frøseth Aae, Per-Henrik Randsborg, Anne Berg Breen, Håvard Visnes, Søren Vindfeld, Einar Andreas Sivertsen, Sverre Løken, Jan Brinchmann, Heidi Andreassen Hanvold, Asbjørn Årøen

    Focal lesions to the articular cartilage in the knee might have demolishing consequences to the knee. There exists a wide range of possible surgical procedures targeting these injuries, however no significant differences have been found between these procedures. This may support that the improvement is a result of rehabilitation, and not the surgery itself. Arthroscopic microfracture (MF) treatment has gained popularity, and has become the treatment of choice in patients with knee cartilage defects globally. In this study we want to increase knowledge, both clinical and economic, about arthroscopic microfracture (AF) compared to arthroscopic debridement (AD) and physical rehabilitation both in the short run, and in the long run. To compare arthroscopic microfracture with arthroscopic debridement and physiotherapy for the treatment of focal cartilage lesions in the knee, a long-term, double-blinded, randomized controlled multicenter trial will be conducted. A total of 114 men and non-pregnant women with a symptomatic focal full thickness cartilage lesion in the knee less than 2 cm2 will be included in the study. The two treatment allocations will receive identical rehabilitation, which is made up of 3 phases: accommodation, rehabilitation and return to activity. Follow up is 24 months, where all will be invited to participate in late follow ups after 5 and 10 years. The Knee Injury and Osteoarthritis Outcome Score (KOOS) knee-related quality of life (QoL) subscore is the primary endpoint. Clinical parameters, questionnaires and radiologic modalities (Magnetic Resonance Imaging (MRI) and x-ray) will be used as secondary endpoints. This is an ongoing multicenter study with a high level of evidence to compare arthroscopic microfracture with arthroscopic debridement and physiotherapy for the treatment of isolated symptomatic full thickness cartilage lesions in the knee joint. ClinicalTrials.gov ID: NCT02637505 (December 15, 2015).


  • Open Access

    Paper #167: Microfracture Technique vs Mosaic Plasty: No Difference in Knee Scores at 5‐11 Years Follow‐up in a Prospective Randomized Clinical Trial

    by Stig Heir, Svend Ulstein, Asbjørn Årøen, Jan Harald Røtterud, Sverre Løken, Lars Engebretsen