Joachim Horn

• Gamage, Thilini Hansamali Gamage Yaddehi; Coutinho, Sílvia; Leardini, Alberto; Alves, Inês; Großmann, Nadine & Sakkers, Ralph [Vis alle 13 forfattere av denne artikkelen] (2026). Clinical decision-making in rare bone diseases – A survey among members of the European Paediatric Orthopaedic Society (EPOS) and the European Reference Network on Rare Bone Diseases (ERN BOND). Journal of Children's Orthopaedics. ISSN 1863-2521. 20(4), s. 428–439. doi: 10.1177/18632521261439074.
• Grønseth, Anders; Rysst-Heilmann, Anne M.S.; Terjesen, Terje Gunerius & Horn, Joachim (2026). Intramedullary Nailing Versus Plate Fixation for Femoral Derotational Osteotomy in Adolescents: A Randomized Controlled Trial. Journal of Pediatric Orthopaedics. ISSN 0271-6798. Publish Ahead of Print. doi: 10.1097/BPO.0000000000003302. Fulltekst i vitenarkiv
• Grønseth, Anders; Horn, Joachim; Liyanarachi, Suki; Gunderson, Ragnhild B. & Terjesen, Terje Gunerius (2025). Long-Term Outcome of Idiopathic Increased Femoral Anteversion in 58 Untreated Individuals at a Mean Age of 46.2 Years. Journal of Pediatric Orthopaedics. ISSN 0271-6798. 46(1), s. 13–19. doi: 10.1097/BPO.0000000000003074. Fulltekst i vitenarkiv
• Vinje, Svend; Terjesen, Terje Gunerius; Horn, Joachim; Hollung, Sandra Julsen & Kibsgård, Thomas Johan (2025). Surgical and health outcomes of non‐ambulatory children with cerebral palsy and severe scoliosis: A population‐based, longitudinal study. Developmental Medicine & Child Neurology. ISSN 0012-1622. doi: 10.1111/dmcn.16473. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Aim To evaluate medium‐term surgical outcomes, complications, mortality, and health‐related quality of life (HRQoL) in non‐ambulatory children with cerebral palsy (CP) and severe scoliosis, and to analyse outcomes and mortality rates in children who had not undergone surgery. Method Data on non‐ambulatory children with CP and severe scoliosis born from 2002 to 2008 were extracted from the Norwegian Quality and Surveillance Registry for Cerebral Palsy. Seventy‐five children (44 males, 31 females) were included. Thirty‐eight (51%; mean age at surgery 14 years 4 months; SD = 2 years 4 months; range = 8–18 years) underwent surgical correction and posterior spinal fusion, with a mean preoperative Cobb angle of 90° (range = 49°–140°), while 37 (49%) children had non‐surgical treatment. HRQoL was measured with the Caregiver Priorities and Child Health Index of Life with Disabilities (CPCHILD). Results Eighteen children (47%) had postoperative complications; 5 of 38 (13%) children underwent further surgery. Surgical treatment improved sitting posture and back pain. The mean CPCHILD score was 49.0 (range = 19–84). Among non‐surgically treated children, 15 of the 31 children considered too fragile to undergo spinal surgery (48%) died during the follow‐up; the mean CPCHILD score for the remaining children was 36.4 points (range = 9–59). Interpretation Although surgical correction of scoliosis in non‐ambulatory children with CP carried a high risk of complications and re‐operations, it resulted in improved sitting posture and reduced back pain. Children who were not eligible for surgical treatment had a high mortality rate.

• Grønseth, Anders; Brattgjerd, Jan Egil & Horn, Joachim (2025). Increasing the precision of intramedullary nailing in femoral derotation osteotomies by larger core locking bolts. A biomechanical study. Clinical Biomechanics. ISSN 0268-0033. 123. doi: 10.1016/j.clinbiomech.2025.106449. Fulltekst i vitenarkiv
• Horn, Joachim; Leardini, Alberto; Benedetti, Maria Grazia; Hestnes, Toril Marie; Mindler, Gabriel & Wekre, Lena Lande [Vis alle 9 forfattere av denne artikkelen] (2025). Fully instrumented gait analysis in rare bone diseases – A scoping review of the literature. Gait & Posture. ISSN 0966-6362. 118, s. 168–177. doi: 10.1016/j.gaitpost.2025.02.001. Fulltekst i vitenarkiv
• Breen, Anne Berg; Steen, Harald; Pripp, Are Hugo; Niratisairak, Sanyalak & Horn, Joachim (2024). Accuracy of 4 Different Methods for Estimation of Remaining Growth and Timing of Epiphysiodesis. Journal of Bone and Joint Surgery. American volume. ISSN 0021-9355. doi: 10.2106/JBJS.23.01483. Fulltekst i vitenarkiv
• Mindler, Gabriel T; Stauffer, Alexandra; Chiari, Catharina; Mladenov, Kiril & Horn, Joachim (2024). Achondroplasia current concept of orthopaedic management. Journal of Children's Orthopaedics. ISSN 1863-2521. Aug 27(18(5)), s. 461–476. doi: 10.1177/18632521241269340. Fulltekst i vitenarkiv Vis sammendrag

  Achondroplasia, the most common form of inherited disproportionate short stature, is caused by mutations in the fibroblast growth factor receptor 3 gene. The typical clinical features of achondroplasia include short stature, rhizomelic disproportion, joint hyperlaxity, spinal deformity and deformity of the upper and lower limbs. The latter are among the challenges of state-of-the-art orthopaedic treatment plans and significantly contribute to the burden of the disease in individuals with achondroplasia. Multidisciplinary preoperative individual decision-making concerning surgical interventions should be considered. New medical treatments for achondroplasia have been developed and (some) have been approved for clinical use in several countries. While the number of research articles on achondroplasia is increasing rapidly, many unknown or controversial orthopaedic topics remain. Furthermore, in view of new medical developments with improvements in growth and potentially other effects, the timing and algorithms of orthopaedic treatments (e.g. guided growth, limb lengthening and deformity correction) need to be re-evaluated. While standing height is the primary research focus in medical therapy, it is crucial to comprehensively assess orthopaedic parameters in this multifactorial disease. The current treatment of patients with achondroplasia requires specialised multidisciplinary centres with transitional care and individual orthopaedic counselling.

• Radler, Christof; Calder, Peter; Eidelmann, Mark; Horn, Joachim; Kold, Søren & Langendörfer, Micha [Vis alle 9 forfattere av denne artikkelen] (2024). What's new in pediatric lower limb reconstruction? Journal of Children's Orthopaedics. ISSN 1863-2521. 18(4), s. 349–359. doi: 10.1177/18632521241258351. Fulltekst i vitenarkiv Vis sammendrag

  The last years brought many advances relevant to lower limb reconstruction. It feels like guided growth has been looked at from every angle, and still there are new emerging concepts like rotational guided growth waiting to be validated. New hexapod external devices are more accurate and easier to use, and new unilateral fixators allow for more versatile and stable fixation and lengthening. Intramedullary nail lengthening has found its place as a standard procedure for various diagnoses in children and young adults. First results of new and exciting approaches like extramedullary implantable nail lengthening and lengthening plates have been reported. Pharmaceutical treatment has changed the course of certain diseases and must be integrated and considered when making a reconstructive treatment plan. As reconstructive surgery is rapidly advancing so are the technical options for prosthetic fitting, which makes it difficult for caregivers as well as for parents to make the decision between reconstruction and amputation surgery for the most severe cases of congenital deficiencies. This review is highlighting new developments of lower limb reconstruction and is reviewing the current literature.

• Breen, Anne Berg; Steen, Harald; Pripp, Are Hugo; Hvid, Ivan & Horn, Joachim (2023). Comparison of Different Bone Age Methods and Chronological Age in Prediction of Remaining Growth Around the Knee. Journal of Pediatric Orthopaedics. ISSN 0271-6798. 43(6), s. 386–391. doi: 10.1097/BPO.0000000000002397. Fulltekst i vitenarkiv
• Iversen, Per Ole; Hankin, Alexandra Renee; Horn, Joachim; Thorkild, Pedersen & Frøen, Hege (2022). Deep Compartment Syndrome Without Myonecrosis: A Case Report on a Rare Complication of Sickle Cell Disease. Cureus - Journal of Medical Science. doi: 10.7759/cureus.29164. Fulltekst i vitenarkiv Vis sammendrag

  Compartment syndrome is a rare manifestation of vaso-occlusive crisis, a serious complication of sickle cell disease (SCD), which is an inherited hemoglobinopathy. During a visit to Norway, an otherwise healthy, 20-year-old male from Ghana was admitted to Oslo University Hospital (Day 1) because of increasing pain in the hip and thighs that did not respond adequately to non-opioid painkillers. Despite initial treatment with intravenous fluids and opioids, his pain intensified. Careful clinical inspection supported by an MRI examination revealed focal, high-signal-intensity muscle edema of the anterior compartment of the thigh, almost exclusively limited to the vastus intermedius muscles. There were no MRI findings or blood biochemistry evidence for myonecrosis or rhabdomyolysis, and a diagnosis of deep compartment syndrome appeared to be the most likely explanation for his pain. We decided to continue with a conservative treatment approach, and the patient did not undergo a fasciotomy or blood transfusion therapy. On Day 7 after admission, his condition improved markedly, and he was discharged on Day 11 whereupon he returned to Ghana. This case is a reminder that, although rare, deep compartment syndrome can be a severe manifestation of vaso-occlusive crisis in SCD and should be considered in patients with severe, deep muscular pain in the absence of other explanatory factors.

• Terjesen, Terje & Horn, Joachim (2022). Risk factors for hip displacement in cerebral palsy: A population-based study of 121 nonambulatory children. Journal of Children's Orthopaedics. ISSN 1863-2521. 16(4), s. 306–312. doi: 10.1177/18632521221113424. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: The aim was to evaluate which clinical and radiographic variables are independent (true) risk factors for hip subluxation in nonambulatory children below 5 years of age with cerebral palsy. Methods: Patients were recruited from a population-based hip surveillance program. Inclusion criteria were birth during 2002–2006, age below 5 years, and gross motor function classification system levels III–V. In all, 121 children (71 boys) met these criteria. Gross motor function classification system was level III in 29 patients, level IV in 28, and level V in 64. Anteroposterior radiographs at diagnosis and during follow-up were assessed, and only the worst hip of each patient was used for the analyses. The mean age at the initial radiograph was 2.5 years (range: 0.7–4.9 years), and the mean follow-up time was 4.0 years (range: 0.5–11.8 years). Results: At the last follow-up, 67 children had a clinically significant hip displacement, defined as migration percentage ≥40%. Univariable regression analysis defined these risk factors: gross motor function classification system level V, spastic bilateral cerebral palsy, initial migration percentage, yearly rate of migration percentage progression, and initial acetabular index. When these variables were analyzed with multivariable regression in 107 patients with initial migration percentage <50% and follow-up ≥1.0 year, the independent risk factors were initial migration percentage (p = 0.003) and yearly rate of migration percentage progression (p < 0.001). Conclusion: The parameters that need to be assessed in hip surveillance in children below 5 years of age are initial migration percentage and rate of migration percentage progression. Acetabular index and femoral head–shaft angle might be useful later for decision-making regarding choice of treatment. Level of evidence: Level II, development of diagnostic criteria.

• Breen, Anne Berg; Steen, Harald; Pripp, Are Hugo; Gunderson, Ragnhild B.; Mentzoni, Hilde Kristine Sandberg & Merckoll, Else [Vis alle 10 forfattere av denne artikkelen] (2022). A comparison of 3 different methods for assessment of skeletal age when treating leg-length discrepancies: an inter- and intra-observer study. Acta Orthopaedica. ISSN 1745-3674. 93, s. 222–228. doi: 10.2340/17453674.2021.1133. Fulltekst i vitenarkiv Vis sammendrag

  Background and purpose — Skeletal maturity is a crucial parameter when calculating remaining growth in children. We compared 3 different methods, 2 manual and 1 automated, in the radiological assessment of bone age with respect to precision and systematic difference. Material and methods — 66 simultaneous examinations of the left hand and left elbow from children treated for leg-length discrepancies were randomly selected for skeletal age assessment. The radiographs were anonymized and assessed twice with at least 3 weeks’ interval according to the Greulich and Pyle (GP) and Sauvegrain (SG) methods by 5 radiologists with different levels of experience. The hand radiographs were also assessed for GP bone age by use of the automated BoneXpert (BX) method for comparison. Results — The inter-observer intraclass correlation coefficient (ICC) was 0.96 for the GP and 0.98 for the SG method. The inter- and intra-observer standard error of the measurement (SEm) was 0.41 and 0.32 years for the GP method and 0.27 and 0.21 years for the SG method with a significant difference (p < 0.001) between the methods and between the experienced and the less experienced radiologists for both methods (p = 0.003 and p < 0.001). In 25% of the assessments the discrepancy between the GP and the SG methodwas > 1 year. There was no systematic difference comparing either manual method with the automatic BX method. Interpretation — With respect to the precision of skeletal age determination, we recommend using the SG method or preferably the automated BX method based on GP assessments in the calculation of remaining growth.

• Weinmayer, Hannah; Breen, Anne Berg; Steen, Harald & Horn, Joachim (2022). Angular deformities after percutaneous epiphysiodesis for leg length discrepancy. Journal of Children's Orthopaedics. ISSN 1863-2521. 16(5), s. 401–408. doi: 10.1177/18632521221115059. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: The purpose of this study was to systematically analyze the presence of secondary angular deformities after percutaneous epiphysiodesis based on long-standing radiographs, and to see if the occurrence and magnitude of angular deformities after percutaneous epiphysiodesis correlated with the amount of remaining growth at the time of surgery. Methods: From a local Health Register consisting of patients investigated using the Moseley Straight-Line Graph, we identified 269 patients who had undergone percutaneous epiphysiodesis from 2002 until 2020. Radiographic analysis included the measurement of mechanical axis and joint orientation angles on long-standing anterior–posterior radiographs. Remaining growth was analyzed based on the Menelaus method. Results: One hundred and forty epiphysiodeses (71 femurs and 69 tibiae) in 88 patients (39 girls and 49 boys) could be included in the study. Mean age at surgery was 13.2 (10–16.8) years, and mean skeletal age at surgery was 13.0 (9.8–15.7) years. A change of the MA (Mechanical axis) ≥10 mm was found in eight patients (9%). Secondary frontal plane deformities after percutaneous epiphysiodesis correlated significantly with the remaining growth at the time of surgery (p = 0.003). Conclusion: We found a high rate of secondary angular deformities after percutaneous epiphysiodesis, and the magnitude of the deformities correlated with the amount of remaining growth at the time of surgery. A modification of the original surgical method for percutaneous epiphysiodesis to also include ablation of central parts of the growth plate might be considered. Patients should be enrolled in a systematic follow-up scheme which allows for the early detection of possible angular deformities. Level of evidence: level III study.

• Bjørge, Patrick Alexander; Tveter, Anne Therese; Steen, Harald; Gunderson, Ragnhild B. & Horn, Joachim (2021). Femoral lengthening might impair physical function and lead to structural changes in adjacent joints: 10 patients with 27 to 34 years’ follow-up. Acta Orthopaedica. ISSN 1745-3674. 92(3), s. 329–334. doi: 10.1080/17453674.2020.1866864. Fulltekst i vitenarkiv Vis sammendrag

  Background and purpose — Literature describing long-term functional outcome and osteoarthritis (OA) in adjacent joints after femoral lengthening is rare. We evaluated physical function and the presence of radiographic OA in adjacent joints in 10 patients ≥ 27 years after femoral lengthening. Patients and methods — We conducted a cross-sectional study of 10 patients treated by unilateral femoral lengthening. Follow-up was between 27 and 34 years. Physical function was evaluated by the 30-second sit-to-stand (30sSTS) and a stair test and was compared with reference values. 4 single-legged hop tests were used to assess difference in physical function between the lengthened and contralateral limb. Radiographic OA was evaluated by joint space width (JSW) and Kellgren and Lawrence (KL) classification. Results — The patients scored worse compared with reference values on the 30sSTS and stair test, and worse on the lengthened limb on the single- and triple-hop test. Radiographic OA was found in the hip or knee in the lengthened limb in 3 of 10 patients based on JSW and 4 of 10 based on KL. No radiographic OA was found in unlengthened limbs. Interpretation — Our results showed impaired physical function both in general and of the lengthened limb. Additionally, we found a possible association between femoral lengthening and radiographic OA in adjacent joints in the long term. However, the sample size of the current study is small.

• Huhnstock, Stefan; Strømme, Hilde & Horn, Joachim (2021). Monteggia fractures in children: A rapid review of injury mechanisms, diagnosis and treatment. Minerva Orthopedics. ISSN 2784-8469. 71, s. 59–70. doi: 10.23736/S2784-8469.20.04054-0. Fulltekst i vitenarkiv
• Horn, Joachim (2021). Treatment of idiopathic increased femoral anteversion in children and adolescents – a perspective. Genij Ortopedii. ISSN 1028-4427. doi: 10.18019/1028-4427-2021-27-4-450-452. Fulltekst i vitenarkiv
• Horn, Joachim; Rasmussen, Hanne; Bukholm, Ida Rashida Khan; Røise, Olav & Terjesen, Terje (2021). Compensation claims in pediatric orthopedics in Norway between 2012 and 2018: a nationwide study of 487 patients. Acta Orthopaedica. ISSN 1745-3674. 92(5), s. 615–620. doi: 10.1080/17453674.2021.1932922. Fulltekst i vitenarkiv Vis sammendrag

  Background and purpose — In Norway all compensation claims based on healthcare services are handled by a government agency (NPE, Norsk Pasientskade Erstatning). We provide an epidemiological overview of claims within pediatric orthopedics in Norway, and identify the most common reasons for claims and compensations.<p> <p>Patients and methods — All compensation claims handled by NPE from 2012 to 2018 within pediatric orthopedics (age 0 to 17 years) were reviewed. Data were analyzed with regard to patient demographics, diagnoses, type of injury, type of treatment, reasons for granted compensation, and total payouts.<p> <p>Results — 487 compensation claims (259 girls, 228 boys) within orthopedic surgery in patients younger than 18 years at time of treatment were identified. Mean age was 12 years (0–17). 150 out of 487 claims (31%) resulted in compensation, including 79 compensations for inadequate treatment, 58 for inadequate diagnostics, 12 for infections, and 1 based on the exceptional rule. Total payouts were US$8.45 million. The most common primary diagnoses were: upper extremity injuries (26%), lower extremity injuries (24%), congenital malformations and deformities (12%), spine deformities (11%), disorders affecting peripheral joints (9%), chondropathies (6%), and others (12%).<p> <p>Interpretation — Most claims were submitted and granted for mismanagement of fractures in the upper and lower extremity, and mismanagement of congenital malformations and disorders of peripheral joints. Knowledge of the details of malpractice claims should be implemented in educational programs and assist pediatric orthopedic surgeons to develop guidelines in order to improve patient safety and quality of care.

• Terjesen, Terje & Horn, Joachim (2021). The femoral head-shaft angle is not a predictor of hip displacement in children under 5 years with cerebral palsy: A population-based study of children at gmfcs levels III-V. Journal of Pediatric Orthopaedics. ISSN 0271-6798. 41(8), s. E659–E663. doi: 10.1097/BPO.0000000000001875. Fulltekst i vitenarkiv Vis sammendrag

  Background: The aim of this study was to evaluate whether the femoral head-shaft angle (HSA) is a predictor of hip displacement in children with cerebral palsy (CP). Methods: The patients were recruited from a population-based hip surveillance program. Inclusion criteria were age under 5 years, bilateral CP, Gross Motor Function Classification System (GMFCS) levels III-V, and migration percentage (MP) of both hips <40% at the primary radiograph. With these criteria, 101 children (61 boys) were included. GMFCS was level III in 26 patients, level IV in 23, and level V in 52. An anteroposterior radiograph of the pelvis was taken at diagnosis and at the last follow-up. Only the worst hip of each patient (the hip with the largest MP) was used for the analyses. Results: The mean age at the primary radiograph was 2.4 years (range, 0.8 to 4.9 y). The mean primary HSA was 171.0 degrees (range, 152 to 190 degrees). The mean follow-up time was 4.3 years (range, 0.9 to 11.8 y). The mean MP at the primary radiograph was 17.5% (range, 0% to 39%) and at the last follow-up 41.9% (range, 0% to 100%). At that point, MP was <40% in 54 hips and ≥40% in 47 hips. There was no significant difference in primary HSA between patients with final MP<40% and those with final MP≥40% (170.8 and 171.3 degrees, respectively; P=0.761). At the last follow-up, the mean HSA was significantly larger in hips with final MP≥40% than in hips with final MP<40% (171.1 vs. 167.4 degrees; P=0.029). Conclusions: There was a markedly increased valgus position of the proximal femur in nonambulatory children with CP. However, the primary HSA in children below 5 years of age was not a predictor of later hip displacement, defined as MP≥40%.

• Terjesen, Terje & Horn, Joachim (2020). Prognostic value of severity of dislocation in late-detected developmental dysplasia of the hip. Journal of Children's Orthopaedics. ISSN 1863-2521. 14(4), s. 266–272. doi: 10.1302/1863-2548.14.200079. Fulltekst i vitenarkiv Vis sammendrag

  Purpose The aims of this study were to evaluate the reliability of three classifications of severity of dislocation in late-detected developmental dysplasia of the hip (DDH), especially to assess whether they are predictive of long-term outcomes. Methods Two groups of patients were analyzed. Group 1 (57 patients, 69 hips) underwent closed reduction between 1958 and 1962. Mean age at reduction was 20.3 months (4 to 65). Group 2 (50 patients, 54 hips) treated between 1996 and 2005, was used for analysis of the association between severity of dislocation and treatment (open or closed reduction). The primary radiographs were graded according to the Tönnis classification, the classification of the International Hip Dysplasia Institute and a new method based on the position of the most lateral point of the proximal femoral metaphysis (lateral metaphysis height classification, LMH). The outcome at a mean age of 51.2 years (55 to 60) was graded according to the occurrence of osteoarthritis (OA) and total hip arthroplasty (THA). Results There were significant associations between the classifications, and the intra- and interobserver agreements were high. More severe grades of DDH were significantly associated with age ≥ 18 months and with open reduction. None of the classifications were significantly associated with long-term OA. The LMH method was significantly associated with the need for THA, whereas the other classifications were not. Conclusion All the classifications were reliable in grading severity of DDH. The LMH method seems preferable in clinical practice because the main landmarks were easy to define and because it had long-term prognostic value. Level of Evidence III

• Vogt, Björn; Gosheger, Georg; Wirth, Thomas; Horn, Joachim & Rödl, Robert (2020). Leg Length Discrepancy— Treatment Indications and Strategies. Deutsches Ärzteblatt International. 117(24), s. 405–411. doi: 10.3238/arztebl.2020.0405. Fulltekst i vitenarkiv
• Terjesen, Terje & Horn, Joachim (2020). Management of late-detected DDH in children under three years of age: 49 children with follow-up to skeletal maturity. Bone & Joint Open (BJO). 1(4), s. 55–63. doi: 10.1302/2633-1462.14.BJO-2019-0005.R1. Fulltekst i vitenarkiv Vis sammendrag

  Aims When the present study was initiated, we changed the treatment for late-detected developmental dislocation of the hip (DDH) from several weeks of skin traction to markedly shorter traction time. The aim of this prospective study was to evaluate this change, with special emphasis on the rate of stable closed reduction according to patient age, the development of the acetabulum, and the outcome at skeletal maturity. Methods From 1996 to 2005, 49 children (52 hips) were treated for late-detected DDH. Their mean age was 13.3 months (3 to 33) at reduction. Prereduction skin traction was used for a mean of 11 days (0 to 27). Gentle closed reduction under general anaesthesia was attempted in all the hips. Concurrent pelvic osteotomy was not performed. The hips were evaluated at one, three and five years after reduction, at age eight to ten years, and at skeletal maturity. Mean age at the last follow-up was 15.7 years (13 to 21). Results Stable closed reduction was obtained in 36 hips (69%). Open reduction was more often necessary in patients ≥ 18 months of age at reduction (50%) compared with those under 18 months (24%). Residual hip dysplasia/subluxation occurred in 12 hips and was significantly associated with avascular necrosis (AVN) and with high acetabular index and low femoral head coverage the first years after reduction. Further surgery, mostly pelvic and femoral osteotomies to correct subluxation, was performed in eight hips (15%). The radiological outcome at skeletal maturity was satisfactory (Severin grades 1 or 2) in 43 hips (83%). Conclusions Gentle closed reduction can be attempted in children up to three years of age, but is likely to be less successful in children aged over 18 months. There is a marked trend to spontaneous improvement of the acetabulum after reduction, even in patients aged over 18 months and therefore simultaneous pelvic osteotomy is not always necessary.

• Horn, Joachim; Hvid, Ivan; Huhnstock, Stefan; Breen, Anne Berg & Steen, Harald (2018). Limb lengthening and deformity correction with externally controlled motorized intramedullary nails: evaluation of 50 consecutive lengthenings. Acta Orthopaedica. ISSN 1745-3674. doi: 10.1080/17453674.2018.1534321. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald; Huhnstock, Stefan; Hvid, Ivan & Gunderson, Ragnhild B. (2017). Limb lengthening and deformity correction of congenital and acquired deformities in children using the Taylor Spatial Frame. Acta Orthopaedica. ISSN 1745-3674. 88(3), s. 334–340. doi: 10.1080/17453674.2017.1295706. Fulltekst i vitenarkiv
• Terjesen, Terje & Horn, Joachim (2016). Have Changes in Treatment of Late-detected Developmental Dysplasia of the Hip During the Last Decades Led to Better Radiographic Outcome? Clinical Orthopaedics and Related Research. ISSN 0009-921X. 474(5), s. 1189–1198. doi: 10.1007/s11999-015-4491-7. Fulltekst i vitenarkiv
• Hvid, Ivan; Horn, Joachim; Huhnstock, Stefan & Steen, Harald (2016). The biology of bone lengthening. Journal of Children's Orthopaedics. ISSN 1863-2521. s. 1–6. doi: 10.1007/s11832-016-0780-2. Fulltekst i vitenarkiv
• Horn, Joachim; Grimsrud, Øyvind; Dagsgard, Anita Hoddevik; Huhnstock, Stefan & Steen, Harald (2015). Femoral lengthening with a motorized intramedullary nail: A matched-pair comparison with external ring fixator lengthening in 30 cases. Acta Orthopaedica. ISSN 1745-3674. 86(2), s. 248–256. doi: 10.3109/17453674.2014.960647. Fulltekst i vitenarkiv
• Terjesen, Terje; Horn, Joachim & Gunderson, Ragnhild B. (2014). Fifty-year follow-up of late-detected hip dislocation: Clinical and radiographic outcomes for seventy-one patients treated with traction to obtain gradual closed reduction. Journal of Bone and Joint Surgery. American volume. ISSN 0021-9355. 96(4), s. e281–e289. doi: 10.2106/JBJS.M.00397. Fulltekst i vitenarkiv
• Horn, Joachim; Gunderson, Ragnhild B.; Wensaas, Anders & Steen, Harald (2013). Percutaneous epiphysiodesis in the proximal tibia by a single-portal approach: evaluation by radiostereometric analysis. Journal of Children's Orthopaedics. ISSN 1863-2521. 7(Oct), s. 295–300. doi: 10.1007/s11832-013-0502-y. Fulltekst i vitenarkiv
• Gunderson, Ragnhild B.; Horn, Joachim; Kibsgård, Thomas Johan; Kristiansen, Leif Pål; Pripp, Are Hugo & Steen, Harald (2013). Negative correlation between extent of physeal ablation after percutaneous permanent physiodesis and postoperative growth Volume computer tomography and radiostereometric analysis of 37 physes in 27 patients. Acta Orthopaedica. ISSN 1745-3674. 84(4), s. 426–430. doi: 10.3109/17453674.2013.810523. Fulltekst i vitenarkiv
• Horn, Joachim; Terjesen, Terje & Steen, Harald (2013). Epidemiology and treatment outcome of congenital pseudartrosis of the tibia. Journal of Children's Orthopaedics. ISSN 1863-2521. 7, s. 157–166. doi: 10.1007/s11832-012-0477-0. Fulltekst i vitenarkiv
• Horn, Joachim; Gueorguiev, B; Brianza, S; Steen, Harald & Schwieger, K (2011). Biomechanical Evaluation of Two-Part Surgical Neck Fractures of the Humerus Fixed by an Angular Stable Locked Intramedullary Nail. Journal of Orthopaedic Trauma. ISSN 0890-5339. 25(7), s. 406–413. doi: 10.1097/BOT.0b013e3181ffdf9a. Fulltekst i vitenarkiv
• Gundersen, Ragnhild B.; Steen, Harald; Horn, Joachim & Kristiansen, Leif Pål (2010). Subsidence of callotasis zone in distraction osteogenesis after external fixator removal, measured by RSA. Acta Orthopaedica. ISSN 1745-3674. 81(6), s. 733–736. doi: 10.3109/17453674.2010.533934. Fulltekst i vitenarkiv
• Horn, Joachim; Kristiansen, Leif Pål & Steen, Harald (2009). Deformity correction during growth after partial physeal arrest. Acta Orthopaedica Belgica. ISSN 0001-6462. 75(2), s. 219–224. Fulltekst i vitenarkiv
• Horn, Joachim; Linke, B.; Höntzsch, D.; Gueorguiev, B & Schwieger, K (2009). Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures: A biomechanical study. Injury. ISSN 0020-1383. 40(7), s. 767–771. doi: 10.1016/j.injury.2009.01.117. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald & Reikerås, Olav (2008). Role of the fibula in lower leg fractures: an in vivo investigation in rats. Journal of Orthopaedic Research. ISSN 0736-0266. doi: 10.1002/jor.20605. Fulltekst i vitenarkiv
• Horn, Joachim; Kristiansen, Leif Pål & Steen, Harald (2008). Partial physeal arrest after temporary transphyseal pinning--a case report. Acta Orthopaedica. ISSN 1745-3674. doi: 10.1080/17453670810016975. Fulltekst i vitenarkiv
• Horn, Joachim; Schlegel, Urs; Krettek, Christian & Ito, Keita (2005). Infection resistance of unreamed solid, hollow slotted and cannulated intramedullary nails: an in-vivo experimental comparison. Journal of Orthopaedic Research. ISSN 0736-0266. doi: 10.1016/j.orthres.2004.11.006. Fulltekst i vitenarkiv

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• Wiig, Ola; Wensaas, Anders; Steen, Harald; Terjesen, Terje; Horn, Joachim & Gunderson, Ragnhild B. (2016). Beinlengdeforskjell (anisomeli). Legeforlaget. ISBN 9788292934159. 13 s. Fulltekst i vitenarkiv

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• Høiness, Per Reidar & Horn, Joachim (2025). Plattfothet hos barn og ungdom. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 145(15). doi: 10.4045/tidsskr.25.0196. Fulltekst i vitenarkiv
• Lødrup, Andreas; Sandbæk, Dan Krister Aas; Brattgjerd, Jan Egil; Reigstad, Ole; Horn, Joachim & Røkkum, Magne [Vis alle 7 forfattere av denne artikkelen] (2024). Nerve- og karskader ved suprakondylære humerusfrakturer hos barn. Fulltekst i vitenarkiv
• Sandbæk, Dan Krister Aas; Lødrup, Andreas; Thorkildsen, Rasmus Dehli; Horn, Joachim; Bere, Tone Tufte & Rörhl, Stephan M. [Vis alle 8 forfattere av denne artikkelen] (2024). Suprakondylære barnebrudd etterundersøkt ved utvokst alder. Fulltekst i vitenarkiv
• Casareto, Lorena; Appelman-Dijkstra, Natasha M.; Brandi, Maria Luisa; Chapurlat, Roland; Cormier-Daire, Valérie & Hamdy, Neveen A.T. [Vis alle 15 forfattere av denne artikkelen] (2024). ERN BOND: The key European network leveraging diagnosis, research, and treatment for rare bone conditions. European Journal of Medical Genetics. ISSN 1769-7212. 68. doi: 10.1016/j.ejmg.2024.104916. Fulltekst i vitenarkiv Vis sammendrag

  There is no universally accepted definition for rare diseases: in Europe a disease is considered to be rare when affecting fewer than 1 in 2000 people. European Reference Networks (ERNs) have been the concrete response to address the unmet needs of rare disease patients and many pan-European issues in the field, reducing inequities, and significantly increasing accessibility to high-quality healthcare across Europe. ERNs are virtual networks, involving centres and patient representatives with the general scope to facilitate discussion on complex cases requiring highly specialised competences and trained expertise. ERN BOND - the European Reference Network on rare BONe Diseases - is one of these 24 approved networks with the specific ongoing mission to implement measures facilitating multidisciplinary, holistic, continuous, patient-centred, and participative care provision to patients, and supporting them in the full realisation of their fundamental human rights. ERN BOND includes in 2023 a total of 53 centres of expertise from 20 European countries. Its governing structure installed in March 2017 includes decision-making, operative and consultative committees, which comprise experts in the field and patient representatives ensuring patient's voice and perspectives are taken into account. Over the years, ERN BOND has worked hard to achieve its mission and valuably contribute to the advancement of diagnosis, management, treatment, and research in rare diseases. The network activities are mainly related to (i) the provision of care which collectively involves averagely 2800 patients diagnosed per year, (ii) the development of education for and training of the healthcare personnel consisting until now in the realisation of 7 thematic workshops and 19 webinars, (iii) the dissemination and exchange and spread of knowledge via network's website (https://ernbond.eu/ ), social media channels, and newsletters, (iv) the management of related data through a disease registry currently mapping over 2300 cases and recording over 600 reported cases, and (v) the enhancement of research which now include two clinical trials endorsed by the network. ERN BOND represents therefore an unprecedented move to improve the healthcare management of patients suffering from rare bone diseases through European collaborations. This network, through the support from the European Health Programme, will continue to pursue its efforts to achieve its goals, always maintaining the patients and their families at the centre of healthcare services.

• Terjesen, Terje Gunerius & Horn, Joachim (2023). Response to comment on Terjesen T and Horn J “Risk factors for hip displacement in cerebral palsy: A population-based study of 121 nonambulatory children”. Journal of Children's Orthopaedics. ISSN 1863-2521. 17(2), s. 193–194. doi: 10.1177/18632521231156550. Fulltekst i vitenarkiv
• Grønseth, Anders; Brattgjerd, Jan Egil & Horn, Joachim (2021). Økt rotasjonsstabilitet med bolter versus skruerved nagling av derotasjonsosteotomier på femur - en biomekanisk studie. Fulltekst i vitenarkiv
• Terjesen, Terje & Horn, Joachim (2020). Response to comment on terjesen and horn: ‘prognostic value of severity of dislocation in late-detected developmental dysplasia of the hip’. Journal of Children's Orthopaedics. ISSN 1863-2521. 14(6), s. 591–592. doi: 10.1302/1863-2548.14.200212. Fulltekst i vitenarkiv
• Breen, Anne Berg; Gunderson, Ragnhild B.; Huhnstock, Stefan; Hvid, Ivan; Kristiansen, Leif Pål & Horn, Joachim [Vis alle 7 forfattere av denne artikkelen] (2017). Korreksjon av benlengdeforskjell ved epifysiodese. Fulltekst i vitenarkiv
• Horn, Joachim; Huhnstock, Stefan; Hvid, Ivan; Steen, Harald & Breen, Anne Berg (2017). Deformity correction and lengthening in the femur and tibia with motorized lengthenng nails. Fulltekst i vitenarkiv
• Horn, Joachim; Huhnstock, Stefan; Hvid, Ivan; Steen, Harald & Breen, Anne Berg (2017). Deformity Correction and Lengthening with Motorized Lengthenng Nails – The Results of 45 Consecutive Lenngthenings. Fulltekst i vitenarkiv
• Horn, Joachim; Huhnstock, Stefan; Hvid, Ivan; Steen, Harald & Breen, Anne Berg (2017). Deformity Correction and Lengthening with Motorized Lengthenng Nails – The Results of 45 Consecutive Lenngthenings. Journal of Limb Lengthening & Reconstruction. ISSN 2455-3719. 3(S16). Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald; Huhnstock, Stefan; Hvid, Ivan & Gunderson, Ragnhild B. (2016). Limb lengthening and deformity correction of congenital and aquired deformities in children using the Taylor Spatial Frame. Fulltekst i vitenarkiv
• Steen, Harald; Gunderson, Ragnhild B.; Kristiansen, Leif Pål; Horn, Joachim; Ludvigsen, Per & Niratisairak, Sanyalak (2016). Ankle arthrodiatasis. Fulltekst i vitenarkiv
• Horn, Joachim; Huhnstock, Stefan; Hvid, Ivan & Steen, Harald (2016). Limb lengthening and deformity correction with motorized lengthening nails. Fulltekst i vitenarkiv
• Horn, Joachim; Huhnstock, Stefan & Steen, Harald (2016). Limb lengthening and deformity correction of congenital and aquired deformities in children using the Taylor Spatial Frame. Journal of Children's Orthopaedics. ISSN 1863-2521. 10, s. 53–53. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald; Huhnstock, Stefan; Hvid, Ivan & Gunderson, Ragnhild B. (2016). Beinforlengelse og aksekorreksjon av medfødte og ervervete deformiteter med Taylor Spatial Frame. Fulltekst i vitenarkiv
• Horn, Joachim; Huhnstock, Stefan; Hvid, Ivan & Steen, Harald (2016). Beinforlengelse med motorisert forlengelsesnagle. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald; Huhnstock, Stefan; Hvid, Ivan & Gunderson, Ragnhild B. (2016). Limb lengthening and deformity correction of congenital and aquired deformities in children using the Taylor Spatial Frame. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald; Huhnstock, Stefan; Hvid, Ivan & Gunderson, Ragnhild B. (2016). Limb lengthening and deformity correction of congenital and aquired deformities in children using the Taylor spatial frame. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald & Gunderson, Ragnhild B. (2015). Radiostereometric analysis of growth after interventions at or around the growth-plate. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald & Gunderson, Ragnhild B. (2015). Radiostereometric analysis of growth after interventions at or around the growth plate. Fulltekst i vitenarkiv
• Rustad, Cecilie; Bjørndalen, Hilde; Myhre, Anne Grethe; Heier, Cathrine Alsaker; Horn, Joachim & Knaus, Andreas [Vis alle 10 forfattere av denne artikkelen] (2015). Re: Spesialpoliklinikk for skjelettdysplasier. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 135(8), s. 736–736. doi: 10.4045/tidsskr.15.0440. Fulltekst i vitenarkiv
• Kierkels, Tessa; Steen, Harald; Jacobsen, Vidar; Niratisairak, Sanyalak; Horn, Joachim & Ito, Keita (2014). The influence of an intact fibula on load-share measurements in leg lengthening with tibial osteotomy - A cadaver study. Fulltekst i vitenarkiv
• Horn, Joachim & Steen, Harald (2014). Femoral lengthening with a motorized intramedullary nail – a matched-pair comparison with Ilizarov external lengthening. Fulltekst i vitenarkiv
• Horn, Joachim & Steen, Harald (2014). Femoral lengthening with a motorized intramedullary nail – a matched-pair comparison with Ilizarov external lengthening. Journal of Children's Orthopaedics. ISSN 1863-2521. 8, s. 40–40. Fulltekst i vitenarkiv
• Horn, Joachim & Steen, Harald (2013). Femoral lengthening with a motorized intramedullary nail – A matched-pair comparison with Ilizarov external lengthening. Fulltekst i vitenarkiv
• Steen, Harald; Gunderson, Ragnhild B.; Kristiansen, Leif Pål; Horn, Joachim & Ludvigsen, Per (2013). Forces and Strain in Arthrodiatasis. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald & Terjesen, Terje (2013). Epidemiology and treatment outcome of congenital pseudartrosis of the tibia. Journal of Children's Orthopaedics. ISSN 1863-2521. 7, s. 13–13. Fulltekst i vitenarkiv
• Steen, Harald; Gunderson, Ragnhild B.; Kristiansen, Leif Pål; Horn, Joachim & Ludvigsen, Per (2013). Forces and Strain in Arthrodiatasis. Fulltekst i vitenarkiv
• Gunderson, Ragnhild B.; Horn, Joachim; Kibsgård, Thomas Johan; Kristiansen, Leif Pål; Pripp, Are Hugo & Steen, Harald (2013). Growth arrest after percutaneous permanent epiphysiodesis: an evaluation using radiostereometric analysis and computer tomography. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald & Terjesen, Terje (2013). Epidemiology and treatment outcome of congenital pseudartrosis of the tibia. Fulltekst i vitenarkiv
• Kivle, Kjetil; Knaus, Andreas; Huhnstock, Stefan; Steen, Harald & Horn, Joachim (2013). Korreksjon av aksedeformiteter rundt kneet med eight-plate. Fulltekst i vitenarkiv
• Horn, Joachim; Steen, Harald; Grimsrud, Øivind & DAGSGARD, A (2013). Femoral lengthening with a motorized intramedullary nail – A matched-pair comparison with Ilizarov external lengthening. Fulltekst i vitenarkiv
• Wiig, Ola; Wensaas, Anders; Høiness, Per Reidar & Horn, Joachim (2011). Kirurgisk dislokasjon av hoften ved epifysiolysis capitis femoris. Fulltekst i vitenarkiv Vis sammendrag

  Bakgrunn: Behandlingen av epifyseolysis capitis femoris har i de aller fleste tilfeller bestått i forsiktig reposisjon og fiksasjon in situ med skruer eller pinner. Åpne prosedyrer har tradisjonelt vært assosiert med høy risiko for avaskulær nekrose. Ganz et al. (2001) publiserte en artikkel som omhandlet kirurgisk dislokasjon av hoften der han demonstrerte en teknikk med full tilgang til caput femoris og acetabulum uten risiko for avaskulær nekrose. Denne teknikken har i økende grad blitt tatt i bruk i behandlingen av epifyseolysis capitis femoris. Materiale og metoder: Vi beskriver teknikken og presenterer to pasienter med epifyseolysis capitis femoris som er operert med kirurgisk dislokasjon av hoften. Pasient 1: 14 år gammel jente som var plaget med intermitterende hoftesmerter i 3 uker, markert forværring siste 2 uker og hun var ute av stand til å belaste 2 dager før innleggelse. Røntgen viser epifyseolyse med stor glidning (90 grader). Initialt forsøkt lukket reposisjon uten hell. Operert med åpen dislokasjon av venstre hofte med collumosteotomi, reposisjon av epifysen og fiksasjon med 2 skruer. Smertefri med normal gangfunksjon og ingen tegn til caputnekrose radiologisk 1 1/2 år etter inngrepet. Pasient 2: 12 år gammel med ubehag høyre hofte 9 måneder forut for innleggelse. Tolket som en kronisk epifyseolyse med stor glidning. Operert med åpen reposisjon, collumosteotomi og pinnefiksering. 5 uker postoperativt fall og smerter. Påvist hofteluksjasjon. Reoperert med åpen reposisjon. Det var pinneperforasjon og bruskdefekt på caput. Ingen smerter og god bevegelighet 3 måneder etter primæroperasjon, men røntgen viser lav leddspalte og defekt på caput. Diskusjon: Kirurgisk dislokasjon av hoften gir god oversikt over caput femoris og acetabulum. Utført korrekt er det rapportert lav risiko for avaskulær nekrose. Det foreligger ingen enighet om indikasjonene for kirurgisk dislokasjon av hoften ved epifyseolysis capitis femoris. Etter vår mening vil det være fornuftig å reservere denne teknikken til de store irreponible akutte glidningene. Ved uttale kroniske eller akutt på kroniske epifyseolyser bør man overveie in situ fiksasjon og senere proksimal femurosteotomi dersom det er behov for kirurgisk korreksjon.

• Gundersen, Ragnhild B.; Steen, Harald; Horn, Joachim; Kristiansen, Leif Pål; Ludvigsen, Per & Lamark, Kathrine (2010). Comment on Shyam et al.: Leg lengthening by distraction osteogenesis using the Ilizarov apparatus: a novel concept of tibia callus subsidence and its influencing factors. International Orthopaedics. ISSN 0341-2695. 34(5), s. 773–774. doi: 10.1007/s00264-010-0981-0. Fulltekst i vitenarkiv
• Vinje, Svend; Kibsgård, Thomas Johan; Terjesen, Terje Gunerius; Jahnsen, Reidun Birgitta & Horn, Joachim (2026). Scoliosis in children with cerebral palsy - A study on scoliosis development, disease progression, surgical treatment outcomes and health-related quality of life. Universitetet i Oslo. ISSN 9788234807466. Fulltekst i vitenarkiv Vis sammendrag

  Children with cerebral palsy (CP) are at increased risk of developing scoliosis. This condition begins early and tends to progress through childhood, particularly among non-ambulatory children. Scoliosis may occur in isolation or in combination with hip displacement (HD) and pelvic obliquity (PO). Population-based screening programmes for children with CP have become a useful source of information and research, and can assist us longitudinally in evaluating these children’s general health, functional abilities and well-being. The aims of this thesis were to assess the development of scoliosis, its progression, surgical treatment outcomes and health-related quality of life (HRQoL) in children with CP. The research comprised a retrospective analysis of population-based data from the NorCP registry, a cross-sectional evaluation of HRQoL using caregiver-reported questionnaires and linkage to the Norwegian Cause of Death Registry to extract information on the causes of death. There was a high prevalence of scoliosis among children with CP, that increased with age and decreasing functional level. The study identified Cobb angle and GMFCS level V as risk factors for the progression of scoliosis and demonstrated a close relationship between scoliosis, hip dysplasia and pelvic obliquity. The combination of HD and scoliosis occurred in about 40% of the children. Furthermore, the study revealed a concerningly high mortality rate among children with severe scoliosis who did not undergo surgical treatment, where the majority of deaths were due to respiratory diseases, mostly pneumonia. Children who underwent surgery achieved improved sitting posture and less back pain, but had a high risk of complications and re-operations. Overall, the findings emphasize the importance of systematic follow-up and early identification of children with CP who are at risk of scoliosis, thereby improving long-term quality of life and functional outcomes.

• Horn, Joachim & Reikerås, Olav (2010). Intramedullary nailing of long bone fractures : Experimental in-vivo and in-vitro studies. Universitetet i Oslo. Fulltekst i vitenarkiv

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