Stephan Maximilian Herbert Röhrl

• Randers, Engelke Marie; Kibsgård, Thomas Johan; Parreiras Nogueira, Liebert; Kjensjord, Trygve; Röhrl, Stephan Maximilian & Nordsletten, Lars [Show all 7 contributors for this article] (2024). Osseointegration of minimally invasive sacroiliac joint fixation implants—A human retrieval study. Journal of Orthopaedic Research. ISSN 0736-0266. doi: 10.1002/jor.25820.
• Randers, Engelke Marie; Gerdhem, Paul; Stuge, Britt Karin; Diarbakerli, Elias; Nordsletten, Lars & Röhrl, Stephan Maximilian [Show all 7 contributors for this article] (2024). The effect of minimally invasive sacroiliac joint fusion compared to sham operation: a double-blind randomized placebo-controlled trial. EClinicalMedicine. ISSN 2589-5370. 68. doi: 10.1016/j.eclinm.2024.102438.
• Øhrn, Frank-David; Engseth, Lars; Pripp, Are Hugo; Röhrl, Stephan Maximilian & Schulz, Anselm (2023). Dose reduction does not impact the precision of CT-based RSA in tibial implants: a diagnostic accuracy study on precision in a porcine cadaver. Acta Orthopaedica. ISSN 1745-3674. 94, p. 550–554. doi: 10.2340/17453674.2023.24022. Full text in Research Archive
• Engseth, Lars; Grønsund, Jørgen; Aunan, Eirik; Brattgjerd, Jan Egil; Schulz, Anselm & Moatshe, Gilbert [Show all 7 contributors for this article] (2023). A novel instrument for ligament balancing: a biomechanical study in human cadaveric knees. Journal of Experimental Orthopaedics. ISSN 2197-1153. 10(1). doi: 10.1186/s40634-023-00643-7. Full text in Research Archive Show summary

  Purpose: Ligament balancing is a prerequisite for good function and survival in total knee arthroplasty (TKA). Various balancing techniques exist, but none have shown superior results. The pie-crusting technique by Bellemans of the medial collateral ligament is commonly utilized; however, it can be difficult to achieve repeatable ligament lengthening with this technique. Therefore, we invented a novel instrument to standardize the pie-crusting technique of the superficial and deep medial collateral ligament (hereafter MCL). The purpose was to examine if pie-crusting with the instrument could produce repeatable ligament lengthening. Methods: The MCL was isolated in 16 human cadaveric knees, and subjected to axial tension. The instrument was composed of a specific grid of holes in rows, used to guide sequential pie-crusting puncturing of the MCL with a Ø1.6 mm end-cutting cannula. Ligament lengthening was measured after each row of punctures. Regression analysis was performed on the results. Results: Mean lengthening ± SD in human cadaveric MCL for puncturing of row 1 in the instrument was 0.06 ± 0.09 mm, 0.06 ± 0.04 mm for row 2, 0.09 ± 0.08 mm for row 3, 0.06 ± 0.05 mm for row 4 and 0.06 ± 0.04 mm for row 5, giving a mean total lengthening of 0.33 ± 0.20 mm. Linear regression revealed that MCLs were repeatably lengthened by 0.07 mm per row when punctured using the instrument. Conclusions: MCLs showed linear lengthening in human cadavers for subsequent use of the instrument. Our instrument shows promising results for repeatable ligament lengthening.

• Poulsen, Magnus; Stødle, Are Haukåen; Nordsletten, Lars & Röhrl, Stephan Maximilian Herbert (2023). CT-based radiostereometric analysis for assessing midfoot kinematics: precision compared with marker-based radiostereometry. Acta Orthopaedica. ISSN 1745-3674. 94, p. 366–372. doi: 10.2340/17453674.2023.16905. Full text in Research Archive
• Rivrud, Sean C. S.; Röhrl, Stephan Maximilian & Leeuwen, Justin Arlen Maarten Joséphus (2023). Effects of patient-specific positioning guides (PSPGs) vs. conventional instrumentation on patient-reported outcome in total knee arthroplasty: secondary analysis of a randomized controlled trial after 5 years. Acta Orthopaedica. ISSN 1745-3674. 94, p. 354–359. doi: 10.2340/17453674.2023.15335. Show summary

  Background and purpose: The use of patient-specific positioning guides (PSPGs) in total knee arthroplasty (TKA) has been advocated as a means of improving patient outcomes, but the reception of PSPGs has been mixed. The aim of our study was to compare patient-reported outcomes (KOOS, NRS-11, EQ-5D-3L, EQ-VAS) after TKA using PSPG with conventional instrumentation (CI) to determine whether there is a discernible clinical benefit to using PSPGs. Patients and methods: This multicenter randomized controlled trial (RCT) followed 77 patients who were randomly assigned to 1 of 2 cohorts between September 2011 and January 2014-one receiving TKA with PSPGs (from Materialise NV) and one receiving TKA with CI-with each cohort followed up until 5 years after the operation. The Vanguard Cruciate Retaining Total Knee System and Refobacin Bone Cement R were used in all operations. KOOS was evaluated using confidence intervals, with differences of less than 10 KOOS units between the cohorts interpreted as indicating the absence of a clinically meaningful difference. Results: No significant differences were found in any of the measured clinical outcomes-KOOS, NRS-11, EQ-5D-3L, EQ-VAS, range of motion, or radiolucent lines scoring-between the cohort operated on using PSPG and the cohort operated on using CI after 5 years of follow-up. Conclusion: There was no statistically significant effect of PSPGs on patient-reported outcomes or range of motion in TKA.

• Engseth, Lars; Schulz, Anselm; Pripp, Are Hugo; Röhrl, Stephan Maximilian & Øhrn, Frank-David (2023). CT-based migration analysis is more precise than radio-stereometric analysis for tibial implants: a phantom study on a porcine cadaver. Acta Orthopaedica. ISSN 1745-3674. 94, p. 207–214. doi: 10.2340/17453674.2023.12306. Full text in Research Archive
• Poulsen, Magnus; Stødle, Are Haukåen; Nordsletten, Lars & Röhrl, Stephan Maximilian Herbert (2022). Does temporary bridge plate fixation preserve joint motion after an unstable Lisfranc injury? Foot and Ankle Surgery. ISSN 1268-7731. p. 1–7. doi: 10.1016/j.fas.2022.12.007. Full text in Research Archive
• Holm Glad, Trygve Andreas; Røkkum, Magne; Röhrl, Stephan Maximilian Herbert; Roness, Siri Pernille; Godang, Kristin & Reigstad, Ole (2022). A randomized controlled trial comparing two modern total wrist arthroplasties : improved function with stable implants, but high complication rates in non-rheumatoid wrists at two years. The Bone & Joint Journal. ISSN 2049-4394. 104-B(10), p. 1132–1141. doi: 10.1302/0301-620X.104B10.BJJ-2022-0201.R2.
• Thoen, Peder Svenkerud; Lygre, Stein Håkon Låstad; Nordsletten, Lars; Furnes, Ove Nord; Stigum, Hein & Hallan, Geir [Show all 7 contributors for this article] (2022). Risk factors for revision surgery due to dislocation within 1 year after 111,711 primary total hip arthroplasties from 2005 to 2019: a study from the Norwegian Arthroplasty Register. Acta Orthopaedica. ISSN 1745-3674. 93, p. 593–601. doi: 10.2340/17453674.2022.3474. Full text in Research Archive Show summary

  Dislocation of a hip prosthesis is the 3rd most frequent cause (after loosening and infection) for hip revision in Norway. Recently there has been a shift in surgical practice including preferred head size, surgical approach, articulation, and fixation. We explored factors associated with the risk of revision due to dislocation within 1 year and analyzed the impact of changes in surgical practice. Patients and methods: 111,711 cases of primary total hip arthroplasty (THA) from the Norwegian Arthroplasty Register were included (2005–2019) after primary THA with either 28 mm, 32 mm, or 36 mm femoral heads, or dualmobility articulations. A flexible parametric survival model was used to calculate hazard ratios for risk factors. Kaplan–Meier survival rates were calculated. Results: There was an increased risk of revision due to dislocation with 28 mm femoral heads (HR 2.6, 95% CI 2.0–3.3) compared with 32 mm heads. Furthermore, there was a reduced risk of cemented fixation (HR 0.6, CI 0.5–0.8) and reverse hybrid (HR 0.6, CI 0.5–0.8) compared with uncemented. Also, both anterolateral (HR 0.5, CI 0.4–0.7) and lateral (HR 0.6, CI 0.5–0.7) approaches were associated with a reduced risk compared with the posterior approach. The time-period 2010–2014 had the lowest risk of revision due to dislocation. The trend during the study period was towards using larger head sizes, a posterior approach, and uncemented fixation for primary THA. Interpretation: Patients with 28 mm head size, a posterior approach, or uncemented fixation had an increased risk of revision due to dislocation within 1 year after primary THA. The shift from lateral to posterior approach and more uncemented fixation was a plausible explanation for the increased risk of revision due to dislocation observed in the most recent time-period. The increased risk of revision due to dislocation was not fully compensated for by increasing femoral head size from 28 to 32 mm.

• Øhrn, Frank-David; Lian, Øystein Bjerkestrand; Tsukanaka, Masako & Röhrl, Stephan Maximillian (2021). Early migration of a medially stabilized total knee arthroplasty : a radiostereometric analysis study up to two years. Bone & Joint Open (BJO). ISSN 2633-1462. 2(9), p. 737–744. doi: 10.1302/2633-1462.29.BJO-2021-0115.R1. Full text in Research Archive Show summary

  Aims Medial pivot (MP) total knee arthroplasties (TKAs) were designed to mimic native knee kinematics with their deep medial congruent fitting of the tibia to the femur almost like a ball-on- socket, and a flat lateral part. GMK Sphere is a novel MP implant. Our primary aim was to study the migration pattern of the tibial tray of this TKA. Methods A total of 31 patients were recruited to this single-group radiostereometric analysis (RSA) study and received a medial pivot GMK Sphere TKA. The distributions of male patients versus female patients and right versus left knees were 21:10 and 17:14, respectively. Mean BMI was 29 kg/m2 (95% confidence interval (CI) 27 to 30) and mean age at surgery was 63 years (95% CI 61 to 66). Maximum total point motions (MTPMs), medial, proximal, and anterior translations and transversal, internal, and varus rotations were calculated at three, 12, and 24 months. Patient-reported outcome measure data were also retrieved. Results MTPMs at three, 12, and 24 months were 1.0 mm (95% CI 0.8 to 1.2), 1.3 mm (95% CI 0.9 to 1.7), and 1.4 mm (0.8 to 2.0), respectively. The Forgotten Joint Score was 79 (95% CI 39 to 95) and Knee Injury and Osteoarthritis Outcome Score obtained at two years was 94 (95% CI 81 to 100), 86 (95% CI 75 to 93), 94 (95% CI 88 to 100), 69 (95% CI 48 to 88), and 81 (95% CI59 to 100) for Pain, Symptoms, Activities of Daily Living, Sport & Recreation, and Quality of Life, respectively. Conclusion In conclusion, we found that the mean increase in MTPM was lower than 0.2 mm between 12 and 24 months and thus apparently stable. Yet the GMK Sphere had higher migration at one and two years than anticipated. Based on current RSA data, we therefore cannot conclude on the long-term performance of the implant, pending further assessment.

• Alm, Carl Erik; Gjertsen, Jan-Erik; Basso, Trude; Matre, Kjell; Röhrl, Stephan Maximillian & Madsen, Jan Erik [Show all 7 contributors for this article] (2021). Trochanteric stabilizing plate in the treatment of trochanteric fractures: a scoping review. Acta Orthopaedica. ISSN 1745-3674. 92, p. 1–6. doi: 10.1080/17453674.2021.1954305. Full text in Research Archive Show summary

  Background and purpose — The trochanteric stabilizing plate (TSP) may be used as an adjunct to a sliding hip screw (SHS) in the treatment of trochanteric fractures to increase construct stability. We performed a scoping review of the literature to clarify when and how the TSP may be useful. Methods — A systematic search was performed in 5 databases and followed by a backwards-and-forwards citation search of the identified papers. 24 studies were included. Results — 6 biomechanical studies and 18 clinical studies were included in the review. The studies presented mainly low-level evidence. All studies were on unstable trochanteric fractures or fracture models. Due to the heterogeneity of methods and reporting, we were not able to perform a meta-analysis. In the biomechanical trials, the TSP appeared to increase stability compared with SHS alone, up to a level comparable with intramedullary nails (IMNs). We identified 1,091 clinical cases in the literature where a TSP had been used. There were 82 (8%) reoperations. The rate of complications and reoperations for SHS plus TSP was similar to previous reports on SHS alone and IMN. It was not possible to conclude whether the TSP gave better clinical results, when compared with either SHS alone or with IMN. Interpretation — The heterogeneity of methods and reporting precluded any clear recommendations on when to use the TSP, or if it should be used at all.

• Fraser, Alexander Nilsskog; Bøe, Berte Marie Grimsmo; Fjalestad, Tore; Madsen, Jan Erik & Röhrl, Stephan Maximillian (2021). Stable glenoid component of reverse total shoulder arthroplasty at 2 years as measured with model-based radiostereometric analysis (RSA). Acta Orthopaedica. ISSN 1745-3674. 92(6), p. 644–650. doi: 10.1080/17453674.2021.1943932. Full text in Research Archive
• Leta, Tesfaye Hordofa; Gjertsen, Jan-Erik; Dale, Håvard; Hallan, Geir; Lygre, Stein Håkon Låstad & Fenstad, Anne Marie [Show all 26 contributors for this article] (2021). Antibiotic-loaded bone cement in prevention of periprosthetic joint infections in primary total knee arthroplasty: A register-based multicentre randomised controlled non-inferiority trial (ALBA trial). BMJ Open. ISSN 2044-6055. 11:e41096, p. 1–8. doi: 10.1136/bmjopen-2020-041096. Full text in Research Archive
• Øhrn, Frank-David; Gøthesen, Øystein; Lygre, Stein Håkon Låstad; Peng, Yi; Lian, Øystein Bjerkestrand & Lewis, Peter L [Show all 8 contributors for this article] (2020). Decreased survival of medial pivot designs compared with cruciate-retaining designs in TKA without patellar resurfacing. Clinical Orthopaedics and Related Research. ISSN 0009-921X. 478(6), p. 1207–1218. doi: 10.1097/CORR.0000000000001120. Full text in Research Archive
• Halvorsen, Vera Baasland; Fenstad, Anne Marie; Röhrl, Stephan Maximillian; Engesæter, Lars B.; Nordsletten, Lars & Terjesen, Terje [Show all 8 contributors for this article] (2020). Hoftelidelser hos barn og unge- utredning og behandling av senfølger. Tidsskrift for Den norske legeforening. ISSN 0029-2001. doi: 10.4045/tidsskr.20.0274. Full text in Research Archive
• Thoen, Peder Svenkerud; Nordsletten, Lars; Pripp, Are Hugo & Röhrl, Stephan Maximillian (2020). Results of a randomized controlled trial with five-year radiostereometric analysis results of vitamin E-infused highly crosslinked versus moderately crosslinked polyethylene in reverse total hip arthroplasty. The Bone & Joint Journal. ISSN 2049-4394. 102-B(12), p. 1646–1653. doi: 10.1302/0301-620X.102B12.BJJ-2020-0721.R1. Show summary

  Aims Vitamin E-infused highly crosslinked polyethylene (VEPE) has been introduced into total hip arthroplasty (THA) with the aim of further improving the wear characteristics of moderately and highly crosslinked polyethylenes (ModXLPE and HXLPE). There are few studies analyzing the outcomes of vitamin E-infused components in cemented arthroplasty, though early acetabular component migration has been reported. The aim of this study was to measure five-year polyethylene wear and acetabular component stability of a cemented VEPE acetabular component compared with a ModXLPE cemented acetabular component. Methods In a prospective randomized controlled trial (RCT), we assessed polyethylene wear and acetabular component stability (primary outcome) with radiostereometric analysis (RSA) in 68 patients with reverse hybrid THA at five years follow-up. Patients were randomized to either a VEPE or a ModXLPE cemented acetabular component. Results Mean polyethylene wear in the proximal direction was 0.17 mm (SD 0.15) for the VEPE group and 0.20 mm (SD 0.09) for the ModXLPE group (p = 0.005) at five years. Annual proximal wear rates were 0.03 mm/year (VEPE) and 0.04 mm/year (ModXLPE). Total 3D wear was 0.21 mm (SD 0.26) and 0.23 mm (SD 0.10) for the VEPE and ModXLPE groups, respectively (p = 0.009). Total 3D cup translation was 0.72 mm (SD 0.70) (VEPE) and 0.50 mm (SD 0.44) (ModXLPE) (p = 0.409). Conclusion At five years, there was less polyethylene wear in the VEPE group than in the ModXLPE group. Both VEPE and ModXLPE cemented components showed low annual wear rates. Component stability was similar in the two groups and remained constant up to five years. Whether these results will equate to a lower long-term revision rate is still unknown.

• Yang, Zhengming; Röhrl, Stephan Maximillian & Nordsletten, Lars (2019). Displaced Acetabular Fracture in Elderly Patients: Is Acute Arthroplasty an Effective Option? Zeitschrift für Orthopädie und Unfallchirurgie. ISSN 1864-6697. 157(6), p. 676–683. doi: 10.1055/a-0842-2320.
• Flatøy, Bernhard; Dahl, Jon; Röhrl, Stephan Maximillian & Nordsletten, Lars (2019). Does radiopaque cement conceal periprosthetic bone loss around femoral stems? HIP International. ISSN 1120-7000. p. 1–8. doi: 10.1177/1120700019863352.
• Halvorsen, Vera Baasland; Fenstad, Anne Marie; Engesæter, Lars B.; Nordsletten, Lars; Overgaard, Søren & Pedersen, Alma B. [Show all 11 contributors for this article] (2019). Outcome of 881 total hip arthroplasties in 747 patients 21 years or younger: data from the Nordic Arthroplasty Register Association (NARA) 1995-2016. Acta Orthopaedica. ISSN 1745-3674. 90(4), p. 331–337. doi: 10.1080/17453674.2019.1615263. Full text in Research Archive
• Brun, Ole-Christian Laahne; Sund, Helge Norheim; Nordsletten, Lars; Röhrl, Stephan Maximillian & Mjaaland, Knut Erik (2019). Component Placement in Direct Lateral vs Minimally Invasive Anterior Approach in Total Hip Arthroplasty: Radiographic Outcomes From a Prospective Randomized Controlled Trial. Journal of Arthroplasty. ISSN 0883-5403. 34(8), p. 1718–1722. doi: 10.1016/j.arth.2019.04.003.
• Lindalen, Einar; Thoen, Peder Svenkerud; Nordsletten, Lars; Høvik, Øystein & Röhrl, Stephan Maximillian (2018). Low wear rate at 6-year follow-up of vitamin E-infused cross-linked polyethylene: a randomised trial using 32- and 36-mm heads. HIP International. ISSN 1120-7000. doi: 10.1177/1120700018798790.
• Holm Glad, Trygve Andreas; Reigstad, Ole; Tsukanaka, Masako; Røkkum, Magne & Röhrl, Stephan Maximillian (2018). High Precision and Accuracy of Model-Based RSA for Analysis of Wrist Arthroplasty. Journal of Orthopaedic Research. ISSN 0736-0266. 36(11), p. 3053–3063. doi: 10.1002/jor.24063.
• Figved, Wender; Svenøy, Stian; Röhrl, Stephan Maximillian; Dahl, Jon; Nordsletten, Lars & Frihagen, Frede Jon (2018). Higher cartilage wear in unipolar than bipolar hemiarthroplasties of the hip at 2 years: A randomized controlled radiostereometric study in 19 fit elderly patients with femoral neck fractures. Acta Orthopaedica. ISSN 1745-3674. 89(5), p. 503–508. doi: 10.1080/17453674.2018.1475899. Full text in Research Archive
• Aunan, Eirik & Röhrl, Stephan Maximillian (2018). No detrimental effect of ligament balancing on functional outcome after total knee arthroplasty: a prospective cohort study on 129 mechanically aligned knees with 3 years` follow-up. Acta Orthopaedica. ISSN 1745-3674. 89(5), p. 548–554. doi: 10.1080/17453674.2018.1485283.
• Fraser, Alexander Nilsskog; Tsukanaka, Masako; Fjalestad, Tore; Madsen, Jan Erik & Röhrl, Stephan Maximillian (2018). Model-based RSA is suitable for clinical trials on the glenoid component of reverse total shoulder arthroplasty. Journal of Orthopaedic Research. ISSN 0736-0266. 36(12), p. 3299–3307. doi: 10.1002/jor.24111.
• Petursson, Gunnar; Fenstad, Anne Marie; Gøthesen, Øystein; Dyrhovden, Gro Sævik; Hallan, Geir & Röhrl, Stephan Maximillian [Show all 8 contributors for this article] (2018). Computer-assisted compared with conventional total knee replacement: A Multicenter Parallel-Group Randomized Controlled Trial. Journal of Bone and Joint Surgery. American volume. ISSN 0021-9355. 100(15), p. 1265–1274. doi: 10.2106/JBJS.17.01338.
• Øhrn, Frank-David; Leeuwen, Justin Arlen Maarten Joséphus; Tsukanaka, Masako & Röhrl, Stephan Maximillian (2018). A 2-year RSA study of the Vanguard CR total knee system: A randomized controlled trial comparing patient-specific positioning guides with conventional technique. Acta Orthopaedica. ISSN 1745-3674. 89(4), p. 418–424. doi: 10.1080/17453674.2018.1470866. Full text in Research Archive Show summary

  Backgound and purpose - There is some concern regarding the revision rate of the Vanguard CR TKA in 1 registry, and the literature is ambiguous about the effi cacy of patient-specifi c positioning guides (PSPGs). The objective of this study was to investigate the stability of the cemented Vanguard CR Total Knee using 2 different surgical techniques. Our hypothesis was that there is no difference in migration when implanting the Vanguard CR with either PSPGs or conventional technique. We hereby present a randomized controlled trial of 2-year follow-up with radiostereometric analysis (RSA). Patients and methods — 40 TKAs were performed between 2011 and 2013 with either PSPGs or the conventional technique and 22 of these were investigated with RSA. Results — The PSPG (8 knees) and the conventional (14 knees) groups had a mean maximum total point motion (MTPM) (95% CI) of 0.83 (0.48–1.18) vs. 0.70 (0.43–0.97) mm, 1.03 (0.60–1.43) vs. 0.86 (0.53–1.19), and 1.46 (1.07– 1.85) vs. 0.80 (0.52–1.43) at 3, 12, and 24 months respectively (p = 0.1). 5 implants had either an MTPM > 1.6 mm at 12 months and/or a migration of more than 0.2 mm between 1- and 2-year follow-ups. 2 of these also had a peripheral subsidence of more than 0.6 mm at 2 years. Interpretation — 5 implants (3 in the PSPG group) were found to be at risk of later aseptic loosening. The PSPG group continuously migrated between 12 and 24 months. The conventional group had an initial high migration between postoperative and 3 months, but seemed more stable after 1 year. Although the difference was not statistically signifi cant, we think the migration in the PSPG group is of some concern

• Leeuwen, Justin Arlen Maarten Joséphus; Snorrason, Finnur & Röhrl, Stephan Maximillian (2018). No radiological and clinical advantages with patient-specific positioning guides in total knee replacement: A multicenter randomized controlled trial. Acta Orthopaedica. ISSN 1745-3674. 89(1), p. 89–94. doi: 10.1080/17453674.2017.1393732. Full text in Research Archive
• Kibsgård, Thomas; Röhrl, Stephan Maximillian; Røise, Olav; Sturesson, Bengt & Stuge, Britt (2017). Movement of the sacroiliac joint during the Active Straight Leg Raise test in patients with long-lasting severe sacroiliac joint pain. Clinical Biomechanics. ISSN 0268-0033. 47, p. 40–45. doi: 10.1016/j.clinbiomech.2017.05.014.
• Aunan, Eirik; Kibsgård, Thomas & Röhrl, Stephan Maximillian (2017). Minimal effect of patella eversion on ligament balancing in cruciate-retaining total knee arthroplasty. Archives of Orthopaedic and Trauma Surgery. ISSN 0936-8051. 137(3), p. 387–392. doi: 10.1007/s00402-017-2625-y. Show summary

  Purpose The effect of patellar eversion on ligament laxity measurements is still unclear. The purpose of this study was to investigate the influence of patellar eversion on medial and lateral ligament laxity measurements performed intra-operatively in total knee arthroplasty (TKA). Methods A total of 49 knees (27 female) with mean age 70 years (42–83) and mean body mass index of 28.5 were operated consecutively with a cruciate-retaining prosthesis. Medial and lateral ligament laxity in extension and in 90° of flexion was measured with the spatula-method intra-operatively after implantation of the prosthetic components with the patella everted and thereafter with the patella repositioned. The corresponding changes in gap height and inclination were calculated. Results A statistically significant increase of 0.6 mm (p < 0.001) in ligament laxity (condylar lift-off) laterally in flexion was found with the patella repositioned compared to everted. No differences were found in extension or medially in flexion. Correspondingly, the flexion gap increased by 0.4 mm (p < 0.001) and the flexion gap inclination increased by 0.6° (p = 0.002) when the patella was repositioned. Conclusions Earlier research has shown that ligament laxity must be at least 1–2 mm to cause inferior function after TKA. In the current study, we found that the effect of patellar eversion on ligament laxity measurements is too small to be considered clinically relevant.

• Tsukanaka, Masako; Støen, Ragnhild Øydna; Figved, Wender; Frihagen, Frede Jon; Nordsletten, Lars & Röhrl, Stephan Maximillian (2017). Steady state acetabular cartilage wear after bipolar hemiarthroplasty: a case series of 10 patients With radiostereometric analysis. HIP International. ISSN 1120-7000. 27(2), p. 193–197. doi: 10.5301/hipint.5000437.
• Tsukanaka, Masako; Röhrl, Stephan Maximillian; von Schewelov, Thord & Nordsletten, Lars (2016). Identification of femoral head center of bipolar hemiarthroplasy in radiostereometric analysis with elementary geometrical shape models. Journal of Biomechanics. ISSN 0021-9290. 49(3), p. 469–473. doi: 10.1016/j.jbiomech.2015.11.054.
• Otten, Volker T.C.; Crnalic, Sead; Röhrl, Stephan Maximillian; Nivbrant, Bo & Nilsson, Kjell G. (2016). Stability of Uncemented Cups - Long-Term Effect of Screws, Pegs and HA Coating: A 14-Year RSA Follow-Up of Total Hip Arthroplasty. Journal of Arthroplasty. ISSN 0883-5403. 31(1), p. 156–161. doi: 10.1016/j.arth.2015.07.012.
• Petursson, Gunnar; Fenstad, Anne Marie; Gøthesen, Øystein; Haugan, Kristin; Dyrhovden, Gro Sævik & Hallan, Geir [Show all 10 contributors for this article] (2016). Similar migration in computer-assisted and conventional total knee arthroplasty: A multicenter, parallel-group, randomized controlled trial involving 54 patients. Acta Orthopaedica. ISSN 1745-3674. 88(2), p. 166–172. doi: 10.1080/17453674.2016.1267835.
• Tsukanaka, Masako; Halvorsen, Vera Baasland; Nordsletten, Lars; Engesæter, Ingvild Øvstebø; Engesæter, Lars B. & Fenstad, Anne Marie [Show all 7 contributors for this article] (2016). Implant survival and radiographic outcome of total hip replacement in patients less than 20 years old. Acta Orthopaedica. ISSN 1745-3674. 87(5), p. 479–484. doi: 10.1080/17453674.2016.1212180.
• Leeuwen, Justin Arlen Maarten Joséphus & Röhrl, Stephan Maximillian (2016). Patient-specific positioning guides do not consistently achive the planned implant position in UKA. Knee Surgery, Sports Traumatology, Arthroscopy. ISSN 0942-2056. p. 1–7. doi: 10.1007/s00167-016-4268-x.
• Flatøy, Bernhard; Röhrl, Stephan Maximillian; Bøe, Berte Marie Grimsmo & Nordsletten, Lars (2016). No medium-term advantage of electrochemical deposition of hydroxyapatite in cementless femoral stems. Acta Orthopaedica. ISSN 1745-3674. 87(1), p. 42–47. doi: 10.3109/17453674.2015.1084768.
• Flatøy, Bernhard; Rydinge, Jonas; Dahl, Jon; Röhrl, Stephan Maximillian & Nordsletten, Lars (2015). Low wear, high stability - promises of success in a moderately cross-linked cup? HIP International. ISSN 1120-7000. 25(3), p. 199–203. doi: 10.5301/hipint.5000230.
• Petursson, Gunnar; Fenstad, Anne Marie; Havelin, Leif Ivar; Gøthesen, Øystein; Lygre, Stein Håkon Låstad & Röhrl, Stephan Maximillian [Show all 7 contributors for this article] (2015). Better survival of hybrid total knee arthroplasty compared to cemented arthroplasty. Acta Orthopaedica. ISSN 1745-3674. 86(6), p. 714–720. doi: 10.3109/17453674.2015.1073539. Full text in Research Archive
• Flatøy, Bernhard; Röhrl, Stephan Maximillian; Rydinge, Jonas; Dahl, Jon; Diep, Lien My & Nordsletten, Lars (2015). Triple taper stem design shows promising fixation and bone remodelling characteristics: Radiostereometric analysis in a randomised controlled trial. The Bone & Joint Journal. ISSN 2049-4394. 97B(6), p. 755–761. doi: 10.1302/0301-620X.97B6.34736.
• Leeuwen, Justin Arlen Maarten Joséphus; Grøgaard, Bjarne; Nordsletten, Lars & Röhrl, Stephan Maximillian (2015). Comparison of planned and achieved implant position in total knee arthroplasty with patient-specific positioning guides. Acta Orthopaedica. ISSN 1745-3674. 86(2), p. 201–207. doi: 10.3109/17453674.2014.985154. Show summary

  Objectives Misinterpretation of radiological examinations is an important contributing factor to diagnostic errors. Double reading reduces interpretation errors and increases sensitivity. Consultant radiologists in Norwegian hospitals submit 39% of computed tomography (CT) reports for quality assurance by double reading. Our objective was to estimate the proportion of radiology reports that were changed during double reading and to assess the potential clinical impact of these changes. Materials and methods In this retrospective cross-sectional study we acquired preliminary and final reports from 1023 consecutive double read chest CT examinations conducted at five public hospitals. The preliminary and final reports were compared for changes in content. Three experienced pulmonologists independently rated the clinical importance of these changes. The severity of the radiological findings in clinically important changes was classified as increased, unchanged, or decreased. Results Changes were classified as clinically important in 91 (9%) of 1023 reports. Of these: 3 were critical (demanding immediate action), 15 were major (implying a change in treatment) and 73 were intermediate (affecting subsequent investigations). More clinically important changes were made to urgent examinations and less to female first readers. Chest radiologist made more clinically important changes than other second readers. The severity of the radiological findings was increased in 73 (80%) of the clinically important changes. Conclusion A 9% rate of clinically important changes made during double reading may justify quality assurance of radiological interpretation. Using expert second readers and targeting a selection of urgent cases prospectively may increase the yield of discrepant cases and reduce harm to patients.

• Lindalen, Einar; Nordsletten, Lars; Høvik, Øystein & Röhrl, Stephan Maximillian (2015). E-vitamin infused highly cross-linked polyethylene: RSA results from a randomised controlled trial using 32 mm and 36 mm ceramic heads. HIP International. ISSN 1120-7000. 25(1), p. 50–55. doi: 10.5301/hipint.5000195.
• Li, Ye; Röhrl, Stephan Maximillian; Bøe, Berte Marie Grimsmo & Nordsletten, Lars (2014). Comparison of two different Radiostereometric analysis (RSA) systems with markerless elementary geometrical shape modeling for the measurement of stem migration. Clinical Biomechanics. ISSN 0268-0033. 29(8), p. 950–955. doi: 10.1016/j.clinbiomech.2014.06.007.
• Kibsgård, Thomas Johan; Røise, Olav; Sturesson, Bengt; Röhrl, Stephan Maximillian & Stuge, Britt (2014). Radiosteriometric analysis of movement in the sacroiliac joint during a single-leg stance in patients with long-lasting pelvic girdle pain. Clinical Biomechanics. ISSN 0268-0033. 29(4), p. 406–411. doi: 10.1016/j.clinbiomech.2014.02.002.
• Aunan, Eirik; Kibsgård, Thomas Johan; Diep, Lien My & Röhrl, Stephan Maximillian (2014). Intraoperative ligament laxity influences functional outcome 1 year after total knee arthroplasty. Knee Surgery, Sports Traumatology, Arthroscopy. ISSN 0942-2056. doi: 10.1007/s00167-014-3108-0. Show summary

  Purpose: To find out if there is an association between ligament laxity measured intraoperatively and functional outcome 1 year after total knee arthroplasty (TKA). Methods: Medial and lateral ligament laxities were measured intraoperatively in extension and in 90° of flexion in 108 patients [122 knees; median age 70 (range 42–83) years]. Mechanical axes were measured preoperatively and at 1-year follow-up. Outcome measures were the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Knee Society Clinical Rating System, the Oxford Knee Score and patient satisfaction. The relationships between laxity and outcome scores were examined by median regression analyses. Results: Post-operative mechanical axis had a significant effect on the association between ligament laxity and KOOS. Therefore, the material was stratified on post-operative mechanical axis. In perfectly aligned and valgus-aligned TKAs, there was a negative correlation between medial laxity and all subscores in KOOS. The most important regression coefficient (β) was recorded for the effect of medial laxity in extension on activities of daily living (ADLs) (β = −7.32, p < 0.001), sport/recreation (β = −6.9, p = 0.017) and pain (β = −5.9, p = 0.006), and for the effect of medial laxity in flexion on ADLs (β = −3.11, p = 0.023) and sport/recreation (β = −4.18, p = 0.042). Conclusions: In order to improve the functional results after TKA, orthopaedic surgeons should monitor ligament laxity and mechanical axis intraoperatively and avoid medial laxity more than 2 mm in extension and 3 mm in flexion in neutral and valgus-aligned knees.

• Dahl, Jon; Snorrason, Finnur; Nordsletten, Lars & Röhrl, Stephan Maximillian (2013). More than 50% reduction of wear in polyethylene liners with alumina heads compared to cobalt-chrome heads in hip replacements A 10-year follow-up with radiostereometry in 43 hips. Acta Orthopaedica. ISSN 1745-3674. 84(4), p. 360–364. doi: 10.3109/17453674.2013.810516.
• Dahl, Jon; Figved, Wender; Snorrason, Finnur; Nordsletten, Lars & Röhrl, Stephan Maximillian (2013). Center index methodan alternative for wear measurements with radiostereometry (RSA). Journal of Orthopaedic Research. ISSN 0736-0266. 31(3), p. 480–484. doi: 10.1002/jor.22241.
• Söderlund, Per; Dahl, Jon; Röhrl, Stephan Maximillian; Nivbrant, Bo & Nilsson, Kjetil G. (2012). 10-year results of a new low-monomer cement Follow-up of a randomized RSA study. Acta Orthopaedica. ISSN 1745-3674. 83(6), p. 604–608. doi: 10.3109/17453674.2012.742392.
• Lindalen, Einar; Dahl, Jon; Nordsletten, Lars; Snorrason, Finnur; Høvik, Øystein & Röhrl, Stephan Maximillian (2012). Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry 43 hips followed for 2 years in a prospective trial. Acta Orthopaedica. ISSN 1745-3674. 83(6), p. 592–598. doi: 10.3109/17453674.2012.742393.
• Röhrl, Stephan Maximillian; Nivbrant, Bo & Nilsson, Kjell G. (2012). No adverse effects of submelt-annealed highly crosslinked polyethylene in cemented cups An RSA study of 8 patients 10 years after surgery. Acta Orthopaedica. ISSN 1745-3674. 83(2), p. 148–152. doi: 10.3109/17453674.2011.652889.
• Aunan, Eirik; Kibsgård, Thomas Johan; Clarke-Jenssen, John & Röhrl, Stephan Maximillian (2012). A new method to measure ligament balancing in total knee arthroplasty: laxity measurements in 100 knees. Archives of Orthopaedic and Trauma Surgery. ISSN 0936-8051. 132(8), p. 1173–1181. doi: 10.1007/s00402-012-1536-1.
• Dahl, Jon; Söderlund, Per; Nivbrant, Bo; Nordsletten, Lars & Röhrl, Stephan Maximillian (2012). Less wear with aluminium-oxide heads than cobalt-chrome heads with ultra high molecular weight cemented polyethylene cups: A ten-year follow-up with radiostereometry. International Orthopaedics. ISSN 0341-2695. 36(3), p. 485–490. doi: 10.1007/s00264-011-1334-3.
• Lindalen, Einar; Nordsletten, Lars & Röhrl, Stephan Maximillian (2012). Segment choice and cup stability influence wear measurements using radiostereometric analysis A radiostereometric study comparing wear measured by markers in the polyethylene with markers in the periacetabular bone. Clinical Biomechanics. ISSN 0268-0033. 27(5), p. 511–514. doi: 10.1016/j.clinbiomech.2011.11.009.
• Figved, Wender; Dahl, Jon; Snorrason, Finnur; Frihagen, Frede Jon; Röhrl, Stephan Maximillian & Madsen, Jan Erik [Show all 7 contributors for this article] (2012). Radiostereometric analysis of hemiarthroplasties of the hip - a highly precise method for measurements of cartilage wear. Osteoarthritis and Cartilage. ISSN 1063-4584. 20(1), p. 36–42. doi: 10.1016/j.joca.2011.11.006.
• Kibsgård, Thomas Johan; Røise, Olav; Stuge, Britt & Röhrl, Stephan Maximillian (2012). Precision and Accuracy Measurement of Radiostereometric Analysis Applied to Movement of the Sacroiliac Joint. Clinical Orthopaedics and Related Research. ISSN 0009-921X. 470(11), p. 3187–3194. doi: 10.1007/s11999-012-2413-5.
• Lindalen, Einar; Havelin, Leif Ivar; Nordsletten, Lars; Dybvik, Eva; Fenstad, Anne Marie & Hallan, Geir [Show all 9 contributors for this article] (2011). Is reverse hybrid hip replacement the solution? 3,963 primary hip replacements with cemented cup and uncemented stem, from the Norwegian Arthroplasty Register. Acta Orthopaedica. ISSN 1745-3674. 82(6), p. 639–645. doi: 10.3109/17453674.2011.623569. Show summary

  Abstract BACKGROUND AND PURPOSE: Reverse hybrid hip replacement uses a cemented all-polyethylene cup and an uncemented stem. Despite increasing use of this method in Scandinavia, there has been very little documentation of results. We have therefore analyzed the results from the Norwegian Arthroplasty Register (NAR), with up to 10 years of follow-up. PATIENTS AND METHODS: The NAR has been collecting data on total hip replacement (THR) since 1987. Reverse hybrid hip replacements were used mainly from 2000. We extracted data on reverse hybrid THR from this year onward until December 31, 2009, and compared the results with those from cemented implants over the same period. Specific cup/stem combinations involving 100 cases or more were selected. In addition, only combinations that were taken into use in 2005 or earlier were included. 3,963 operations in 3,630 patients were included. We used the Kaplan-Meier method and Cox regression analysis for estimation of prosthesis survival and relative risk of revision. The main endpoint was revision for any cause, but we also performed specific analyses on different reasons for revision. RESULTS: We found equal survival to that from cemented THR at 5 years (cemented: 97.0% (95% CI: 96.8-97.2); reverse hybrid: 96.7% (96.0-97.4)) and at 7 years (cemented: 96.0% (95.7-96.2); reverse hybrid: 95.6% (94.4-96.7)). Adjusted relative risk of revision of the reverse hybrids was 1.1 (0.9-1.4). In patients under 60 years of age, we found similar survival of the 2 groups at 5 and 7 years, with an adjusted relative risk of revision of reverse hybrids of 0.9 (0.6-1.3) compared to cemented implants. INTERPRETATION: With a follow-up of up to 10 years, reverse hybrid THRs performed well, and similarly to all-cemented THRs from the same time period. The reverse hybrid method might therefore be an alternative to all-cemented THR. Longer follow-up time is needed to evaluate whether reverse hybrid hip replacement has any advantages over all-cemented THR.

• Bøe, Berte Marie Grimsmo; Röhrl, Stephan Maximillian; Heier, Tore; Snorrason, Finnur & Nordsletten, Lars (2011). A prospective randomized study comparing electrochemically deposited hydroxyapatite and plasma-sprayed hydroxyapatite on titanium stems. Acta Orthopaedica. ISSN 1745-3674. 82(1), p. 13–19. doi: 10.3109/17453674.2010.548027.

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• Sandberg, Olof H.; Kärrholm, Johan; Olivecrona, Henrik; Röhrl, Stephan Maximilian Herbert; Sköldenberg, Olof G. & Brodén, Cyrus (2023). Computed tomography-based radiostereometric analysis in orthopedic research: practical guidelines. Acta Orthopaedica. ISSN 1745-3674. 94, p. 373–378. doi: 10.2340/17453674.2023.15337. Full text in Research Archive
• Pripp, Are Hugo; Schulz, Anselm; Röhrl, Stephan Maximilian Herbert & Øhrn, Frank-David (2022). Presisjon av et nytt CT-basert analyseprogram sammenlignet med radiostereometrisk analyse – en fantomstudie på gris .
• Grønsund, Jørgen; Aunan, Eirik; Brattgjerd, Jan Egil; Schulz, Anselm; Moatshe, Gilbert & Röhrl, Stephan Maximilian Herbert (2022). A novel instrument for ligament balancing in Total Knee Arthroplasty – a biomechanical study in porcine tissue.
• Aunan, Eirik; Schulz, Anselm; Moatshe, Gilbert; Brattgjerd, Jan Egil; Grønsund, Jørgen & Röhrl, Stephan Maximilian Herbert (2022). A novel instrument for ligament balancing in Total Knee Arthroplasty – a biomechanical study in porcine and human tissue.
• Röhrl, Stephan Maximillian (2020). “Great balls on fire:” known algorithm with a new instrument? Acta Orthopaedica. ISSN 1745-3674. 91(6), p. 621–623. doi: 10.1080/17453674.2020.1840029.
• Leeuwen, Justin Arlen Maarten Joséphus & Röhrl, Stephan Maximillian (2015). Comparison Of Planned And Achieved Implant Position In Medial Unicompartmental Knee Arthroplasty (UKA) With Patient Specific Positioning Guides (PSPG).
• Petursson, Gunnar ; Gøthesen, Øystein; Fenstad, Anne Marie; Dyrhovden, Gro Sævik; Haugan, Kristin & Havelin, Leif Ivar [Show all 11 contributors for this article] (2014). Computernavigasjon vs konvensjonell teknikk ved kneprotesekirurgi. En prospektiv, randomisert, blindet RSA-studie.

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