Reliability of measures used in radiographic evaluation of the adult hip.

OBJECTIVE: The reliability of radiographic measurements has been studied in pediatric hips, but less has been published on the adult hip, and none have examined the reliability of measurements for the location of the center of rotation (COR) of the hip joint. We have investigated the reliability of various radiographic variables with a focus on the COR. MATERIALS AND METHODS: The study was carried out on a standardized format for anterior-posterior radiographs of the pelvis. The measured variables were; (A) the distance from a sagittal reference line to the COR, (B) the distance from the sagittal reference line to the proximal end of the lateral cortical line of the femur, (C) the distance from the sagittal reference line to the medial rim of the acetabulum, (D) the distance from the horizontal reference line to the roof of the acetabulum, and (E) the distance from the horizontal reference line to the COR. One observer (JAB) conducted the measurements twice separated by a time interval of 45-60 days to assess intra-observer reliability, and the first measurements of JAB were compared to those performed by another observer (OR) to assess inter-observer reliability. RESULTS: Intraclass correlation coefficients were above 0.98 for all measurements, and the minimum and maximum values that statistically include 95% of the observer differences were all within -3 to +3 mm. CONCLUSIONS: These measurements proved to have high reliability and agreement of both within the same observer and between two observers. They should therefore be reproducible in a clinical setting.

No difference in mortality between cemented and uncemented hemiprosthesis for elderly patients with cervical hip fracture. A prospective randomized study on 334 patients over 75 years.

INTRODUCTION: Laboratory and human mechanical studies indicated that chemical substances in bone cement had toxic and prothrombotic effects. Impaction of cement added a mechanical trauma to the reaming and broaching procedure and contributed to a substantial local and systemic thrombin generation. Case reports and materials have indicated bone cement as the immediate trigger of cardiorespiratory and vascular dysfunction, occasionally fatal, and described as the bone cement implantation syndrome. In spite of this knowledge, bone cement has gained popularity and is widely used for prosthesis fixation, possibly due to a lack of clinical evidence supporting the basic science indicating bone cement as a mortality risk factor. METHOD: This is a prospective, randomized study comparing cemented and non cemented hemiprosthesis on patients suffering a dislocated cervical hip fracture. Perioperative characteristics and 1 year mortality differences between the groups were estimated. PATIENTS: Hundred and thirty-four patients over 75 years were enrolled from two hospitals in Norway. Average age was 84 years, 75 % were female and 60 % had symptomatic comorbidities. RESULTS: We find no difference in mortality between cemented and uncemented hemiprosthesis up to 1 year (HR 0.77, 95 % CI 0.51-1.18, p = 0.233). However, statistically significant reduced operation time and blood loss were found in the non-cemented group. (mean difference of 13 min, 95 % CI 4-22, p = 0.004 and 92 ml 95 % CI 3-181, p = 0.043, respectively). CONCLUSION: Installation of non-cemented hemiprostheses in elderly with hip fracture may have benefits perioperatively regarding operation time and bleeding, and do not seem to influence 1 year mortality relative to cemented implants.

Components anteversion in primary cementless THA using straight stem and hemispherical cup: a prospective study in 91 hips using CT-scan measurements.

BACKGROUND: The recommended range of anteversion of the components in total hip arthroplasty (THA) is between 10 and 30°, but the intraoperative estimation of these versions may be inadequate. HYPOTHESIS: The components anteversion in primary cementless THA using straight stem and hemispherical cup is not significantly different from the native anteversion of the hip joint. OBJECTIVES: To evaluate in a prospective manner the range of anteversion currently achieved in cementless THA. PATIENTS AND METHODS: Five senior surgeons operated 91 patients with primary cementless THA. We used a straight press fit stem and a hemispherical press fit cup. We aimed to obtain femoral anteversion of 10 to 30°, acetabular anteversion of 10 to 30° and a global combined anteversion of 25 to 55°. Cup position was checked with an impactor-positioner, and stem position was determined with the knee flexed 90°. In all cases we used elevated liners and 28 mm diameter ceramic heads. At 3 months postoperatively the component versions were measured using a General Electric LightSpeed Pro 16 (Milwaukee, Wi, USA) with the patient in supine position. RESULTS: Femoral component measurements ranged from 17° of retroversion to 60° of anteversion with a mean of 23.0±11.8°. Similarly, acetabular component version ranged from 28° of retroversion to 46° of anteversion with a mean of 18.5±13.7°. There were no correlations to the native femoral and acetabular versions. Only 55 hips (60.4%) were within the accepted range of 25 to 55° of combined anteversion, but none of the cases dislocated during a follow-up of 2 years. CONCLUSION: In cementless THA with our operative technique, the intraoperative estimation of femoral and acetabular anteversion, in many cases, resulted to be inadequate in relation to the intended range of 10 to 30° of anteversion.

The epidemiology of shoulder dislocations in Oslo.

There are few previous studies on the incidence of shoulder dislocation in the general population. The aim of the study was to report the incidence of acute shoulder dislocations in the capital of Norway (Oslo) in 2009. Patients of all ages living in Oslo, sustaining a dislocation of the glenohumeral joint, were identified using electronic diagnosis registers, patient protocols, radiological registers of the hospitals, and the Norwegian Patient Register (NPR). The overall incidence rate was 56.3 [95% confidence interval (CI) 50.2-62.4] per 100,000 person-years, with rates of 82.2 (95% CI 71.7-92.8) and 30.9 (95% CI 24.5-37.3) in men and women, respectively. The incidence of primary dislocations was 26.2 (95% CI 22.1-30.4). The overall incidence of shoulder dislocations in Oslo was higher than previously reported incidences. The incidence of primary dislocations was also higher than that in previously reported studies for the general population but it was close to the incidence reported in Malmø, Sweden.

Impact of freezing on bone graft incorporation biomechanical evaluations in rats.

BACKGROUND: With an increasing clinical application of grafting for bone reconstruction, it is important to understand the physiological and biological events of graft incorporation. In this study, we have investigated the impact of deep freezing on the biopotency for incorporation of bone grafts. METHODS: Fresh and deep-frozen autogenous bone grafts were implanted in an 8-mm segmental defect in the tibia. The construct was stabilized with intramedullary nailing. Incorporation of the graft was assessed with use of conventional radiography, biomechanical testing and measurements of bone mineral content and density after 2 and 4 months, respectively. FINDINGS: Frozen grafts were significantly less integrated after 2 months as compared to fresh grafts. After 4 months, however, the frozen grafts showed an overall reconstruction that was not significantly different from the fresh grafts. Both frozen and fresh grafted segments had only reached 70% strength of intact bone at 4 months. INTERPRETATION: This study indicates that in the long run there are no significant consequences, radiologically or biomechanically, of deep freezing as compared to fresh bone grafts.

Systemic and local cytokine kinetics in musculoskeletal injury: a prospective study in patients with ankylosing spondylitis.

OBJECTIVE: Back surgery in patients with ankylosing spondylitis is a major trauma in individuals with tissue inflammation and joint destruction along the spine; we used surgery in these patients as a model in the study of systemic and local cytokine profiles in complicated trauma situations. MATERIAL AND METHODS: Blood was sampled before, during and after surgery in 10 patients operated on with extending osteotomy of the lumbar spine. Samples of arterial blood and local wound blood were analysed for proinflammatory and anti-inflammatory cytokines. RESULTS: Surgery induced no significant changes in systemic values of TNFalpha and IL-1beta. There were significant increments in systemic values of IL-6, IL-8 and sTNF-R1. A systemic increase in values of IL-10 was only noticed after 24 h. There were increments in local values of TNFalpha at 24 h and in local values of IL-1beta, IL-6, Il-8 and IL-10 at both 4 and 24 h postoperatively. The local values were in general significantly higher than the systemic values. CONCLUSIONS: This study indicates that a major musculoskeletal trauma principally is followed by significant increases in systemic levels of IL-6 with only modest systemic reactions in TNFalpha and IL-1beta, even in patients with an inflammatory disease. However, there are in general significantly increased local levels of IL-1beta, IL-6, IL-8 and IL-10, and our conclusion is that systemic cytokine levels might not reflect local reactions.

Systemic and local cytokine kinetics after total hip replacement surgery.

BACKGROUND: Trauma induces local and subsequent systemic inflammatory reactions. Aberrant reactions can lead to a systemic inflammatory response syndrome, with a potentially lethal outcome. Our aim was to investigate the early local cytokine kinetic compared to systemic changes in a standardized surgical trauma. METHODS: In 7 patients with total hip replacement, drained blood samples and venous blood samples were taken 3 times within the first day after the operation. Interleukin (IL) release was assessed by a multiplex antibody bead kit and compared to pre-operative values. RESULTS: The major findings were significant increases in systemic levels of IL-6 and in local levels of IL-6, IL-8 and IL-1 receptor antagonist (IL-1Ra), and that the local levels of these cytokines were significantly higher than the systemic ones after surgery. Besides, there were only modest changes in local and systemic levels of tumour necrosis factor alpha, IL-1 beta, IL-2, IL-2Ra, IL-4, IL-5, IL-7, IL-10, IL-12, IL-13, IL-15 and IL-17. CONCLUSIONS: The acute sterile inflammation after major orthopaedic surgery is principally characterized by significantly increased local and systemic levels of IL-6 and significantly increased local levels of IL-8 and IL-1Ra. Furthermore, the concentrations are higher at the local site of injury. Hence, we conclude that systemic cytokine levels might not reflect local reactions.

Hip arthroplasty in patients younger than 30 years: excellent ten to 16-year follow-up results with a HA-coated stem.

It is well accepted that youth and high activity levels are among the factors that increase the risk of mechanical failure of total hip prostheses. However, there are few reports of long-term results in very young patients. In this study, we evaluated the results of total 49 hip replacements (THRs) using an uncemented total hip prosthesis in 44 patients (28 females) who were 30 years or younger (range: 15-30 years). The diagnosis was ostearthritis due to congenital dislocations in 28 patients, with the remaining patients having diagnoses of sequelae of fracture, infection, Calve-Legg-Perthes disease, avascular necrosis, chondrodystrophia and epiphyseal dysplasia. In all cases we used an uncemented straight stem fully coated with hydroxyapatite (HA). In 36 cases we used a hemispherical cup inserted with press fit, and in seven cases we used a hemispherical screw cup. The patients were evaluated ten to 16 years (mean: 13 years) after the operation by radiographic and clinical examinations, including the Harris Hip, WOMAC and EuroQol-5D scores. In a sub-group of nine patients with a unilateral prosthesis, the muscle strength of the quadriceps and hamstrings was tested using a Cybex 6000. None of the stems were revised at the follow-up examination, and all were classified as well integrated, with no signs of radiological loosening. Twenty-four hips had revision of the acetabular component due to mechanical failure. The Harris Hip score was, on average, 88 (range: 62-100), the WOMAC score 80 (range: 37-100) and the EuroQol score 0.68 (range: -0.14-1). Isokinetic muscle strength testing showed that seven of the nine tested patients were weaker on the operated side. In conclusion, we found mechanical failures at the acetabular side, but excellent results with a fully HA-coated femoral stem, with no revisions after ten to 16 years.

Cytokine patterns after tourniquet-induced skeletal muscle ischaemia reperfusion in total knee replacement.

OBJECTIVE: Extremity surgery performed under tourniquet control causes one of the most common forms of skeletal muscle ischaemia-reperfusion injury in clinical practice. The aim of this study was to investigate the systemic and local inflammatory response after tourniquet-induced skeletal muscle ischaemia-reperfusion injury in patients undergoing total knee replacement. It was our hypothesis that local inflammatory responses in a surgical wound under tourniquet-induced ischaemia cause an excessive overflow of cytokines to the systemic circulation in the reperfusion phase. MATERIAL AND METHODS: Blood was sampled before and after surgery in nine patients given total knee replacement. Samples from ischaemic and non-ischaemic limbs and from drained blood were analysed for pro-inflammatory and anti-inflammatory cytokines. RESULTS: Surgery induced significant increases of IL-6 (p = 0.007) in the non-ischaemic (systemic) limb and in drained blood (p = 0.032), with highest levels 4 h after operation. The increased IL-6 in the ischaemic limb was non-significant. IL-1 beta was not detectable under surgery, from either the traumatized limb or from the non-traumatized limb, nor were TNFalpha and IL-10 significantly influenced by surgery. CONCLUSIONS: Knee replacement trauma performed under ischaemia, is associated with modest systemic inflammatory reactions with no spillover of increased IL-6 from the traumatized area in the reperfusion phase.

Fibre optic Bragg grating sensors: an alternative method to strain gauges for measuring deformation in bone.

Strain gauges are currently the default method for measuring deformation in bone. Strain gauges are not well suited for in vivo measurements because of their size and because they are difficult to use in bone. They are also unsuitable for repeated measurements over time since they cannot be left in the patient. The optical Bragg grating fibres behave like selective filters of light. As a result the structure will transmit most wavelengths of light, but will reflect certain specific wavelengths. If the Bragg grating is strained along the fibre axis, the wavelength will shift, and this change represents a measure of strain. The optical fibres are very thin, no thicker than a standard surgical suture and are easy to adhere to bone by use of the FDA approved polymethyl-methacrylate (PMMA) as bonding adhesive. Since they are made of biocompatible silica porous bioglass ceramics, it should also be possible to leave the fibres in the patient between and after measurements. We have shown that fibre optic Bragg grating sensors can be used as a measurement tool for bone strain by performing measurements both on an acryl tube and on an extracted sample of human femur diaphysis. On either of them we used four fibre optic sensors and four strain gauges, interspersed at every 45 degrees around the circumference. The standard deviation of the measurements on the acrylic tube for each of the sensors, both optical fibres and strain gauges, varied from 1.0 to 5.2%. Every sensor, both optical fibre and strain gauge, correlated significantly with all of the rest at the 0.01 level with a Pearson correlation coefficient r ranging from 0.986 to 1.0. The linearity for all of the sensors versus load was excellent, the lowest linearity of the eight sensors was 0.996 as expressed by r(2) (coefficient of determination), with no significant difference in linearity between optical fibres and strain gauges. Bone is not an ideal isotropic material, and we found that the strain readings of the sensors in the bone study showed less linearity than in the acryl tube study. The correlations between all sensors, both optical fibres and strain gauges, were less strong in the bone sample than acrylic tube with a Pearson correlation coefficient on the bone sample ranging from 0.629 to 0.999 and with a standard deviation of the measurements varying from 3.1 to 31.5%. However, no significant differences between strain gauges and optic fibres were found, neither in the acrylic tube measurements nor the bone sample measurements. Optical Bragg grating fibres are therefore well suited for dynamic measurements of strain in bone in vitro and should also be suitable for use on bone in vivo.

Investigation of lipopolysaccharide receptor expression on human monocytes after major orthopaedic surgery.

BACKGROUND: The innate immune system is suppressed after major orthopaedic surgery, implicating a risk of septic complications. Whole-blood ex vivo testing with lipopolysaccharide (LPS) has shown a depression of the tumour necrosis factor alpha (TNF-alpha) production until 12 days postoperatively. As part of the innate immune system, the Toll-like receptors TLR2 and TLR4 recognize antigens from Gram-positive and Gram-negative bacteria, respectively. The receptors CD14 and CD11b are involved in the LPS receptor complex, whereas human lymphocyte antigen (HLA)-DR binds endotoxin peptides. It is still uncertain whether the expression of all these receptors changes after major surgery. METHODS: In 6 patients undergoing hip arthroplasty, we investigated three times the display of TLR4, TLR2, CD14, CD11b, and HLA-DR on monocytes by fluorescence-activated cell sorting and white blood cell counts during 12 days postoperatively. At the same time, the plasma levels of interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-13, and TNF-alpha were measured. RESULTS: There was no significant change in the expression of TLR4, CD14, CD11b, HLA-DR, and TLR2. Monocyte count and cytokine analysis did not differ from the ones pre-operatively taken. CONCLUSIONS: After aseptic orthopaedic surgery, there is no change in the display of the LPS receptor complex on monocytes. Other mechanisms have to be investigated to gain insight into the decrease of the TNF-alpha production capacity postoperatively.

Immune modulation after total hip surgery. A prospective ex vivo study.

BACKGROUND: Major trauma affects the immune system, and immunosuppression may render the patients susceptible to septic complications. The purpose of this study was to investigate lipopolysaccharide (LPS)-induced releases of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in whole blood in patients undergoing total hip replacement. METHODS: Seven patients (6 females) who underwent elective total hip replacement were included. Ex vivo LPS-induced releases of TNF-alpha and IL-6 were measured in a whole blood assay at days 1, 6, 9 and 12 postoperatively, using low- and high-dose LPS incubation. At the same time, white blood cell counts were analyzed. RESULTS: The amount of TNF-alpha release was significantly reduced at days 6 and 12. Compared to monocyte counts, TNF-alpha release was significantly decreased also at day 9 in low- and high-dose LPS stimulation. IL-6 in plasma was significantly increased at day 1 and normalized thereafter. There were no differences in LPS-induced IL-6 levels compared to the levels before surgery. CONCLUSION: This in vivo/ex vivo study shows a reduced capacity of whole blood to release LPS-induced TNF-alpha at day 6 through to day 12 after major orthopedic surgery. Attenuated TNF-alpha release may contribute to an increased postoperative susceptibility to gram-negative sepsis.

Incidence of hip fracture in southeastern Norway: a study of 1,730 cervical and trochanteric fractures.

The incidence of hip fracture has been studied extensively, but there is still some doubt whether the age-specific incidence is increasing. The proportion of trochanteric fractures has varied and has also been said to be increasing. We studied data on 1,730 prospectively registered cases from 1998-2003 and computed age- and gender-specific incidence rates for intracapsular and trochanteric fractures. The incidence of hip fracture for women over 50 years was 1,263 and for men 452 per 100,000. The proportion of trochanteric fractures was 38% for women and 41% for men. There was no significant difference in the proportion of trochanteric fractures either between or within the genders, and the proportion did not exceed 50% in any age group. These findings confirm the high incidence of hip fracture in Norway but do not indicate any increase. The proportion of trochanteric fractures also seems to be stable.

Systemic and local cytokine patterns during total hip surgery.

OBJECTIVE: Increased levels of inflammatory cytokines have been described in musculoskeletal injury. Total hip replacement is major musculoskeletal surgery, and in the present study this operation was used to investigate systemic and local cytokine patterns during musculoskeletal trauma. MATERIAL AND METHODS: Blood was sampled before, during and after surgery in 10 patients given total hip replacement. Samples of arterial blood and local blood from the femoral canal were analysed for proinflammatory and anti-inflammatory cytokines. RESULTS: Surgery induced significant increases in arterial and local levels of interleukin 6 (IL-6) (p = 0.000, respectively) with the highest levels at 4 h after operation. There were significantly higher local levels of IL-6 than arterial levels. Interleukin 1beta (IL-1beta) was not significantly influenced by surgery at any time (p = 0.800 and 0.300 for local and arterial levels, respectively), nor was tumour necrosis factor alpha (TNFalpha) (p = 0.375 and 0.547 for local and arterial levels, respectively). Local levels were higher than arterial levels for IL-1beta and for TNFalpha. At the end of the operation, local levels of interleukin 10 (IL-10) were significantly reduced (p = 0.036), while surgery did not influence the arterial levels of IL-10 (p = 0.235). There were no significant differences in local and arterial levels of IL-10 (p = 0.558). CONCLUSIONS: The study indicates that a major musculoskeletal operation on otherwise healthy patients is associated with fairly modest reactions of inflammation, both systemically and locally.

Elevated plasma beta-endorphin/beta-lipotropin concentration following a radius fracture.

Plasma beta-endorphin/beta-lipotropin concentration was assessed soon after a fracture. Blood samples from 14 patients with radius fractures were obtained from both arms soon after admission to the hospital (mean 245 min) after the accident. Follow-up samples were taken after healing of the fractures. Higher plasma beta-endorphin/beta-lipotropin concentrations were found in blood samples taken soon after a fracture in both arms compared with the concentrations after healing of the fracture. At admission, mean beta-endorphin/beta-lipotropin concentrations in the fractured and the contralateral arms were 12.7 pmol/L and 13.2 pmol/L, and after recovery 11.1 pmol/L and 11.5 pmol/L (p = 0.012 and p = 0.041), respectively. The pain decreased according to the visual analogue scale (VAS) (0-10) from 4.64 at admission to 0.58 after healing (p < 0.001). In conclusion, this study showed that beta-endorphin/beta-lipotropin concentrations are increased in both arms following a radius fracture compared to the level after the fracture has healed.

Effective pain relief from intra-articular saline with or without morphine 2 mg in patients with moderate-to-severe pain after knee arthroscopy: a randomized, double-blind controlled clinical study.

BACKGROUND: Intra-articular (IA) morphine has given good and prolonged pain relief in some studies when given at the end of arthroscopic procedures in the knee joint. However, similar studies have not been able to document any local analgesic effect of morphine. A large number of the negative studies have not demonstrated any assay sensitivity. We have documented that around 40% of patients have only very mild or no pain after arthroscopic procedures in the knee joint. This obviously is a confounding factor, reducing assay sensitivity when all patients are included in IA morphine studies. METHOD: By leaving a soft catheter IA in 57 patients and including only patients who developed moderate-to-severe pain within 1 h after an arthroscopic procedure in the knee joint under general anaesthesia, we included 40 patients. These patients had a mean pre-treatment baseline pain of about 50/100 on a 100-mm visual analogue scale (VAS) for pain intensity. A randomized, double-blind controlled comparison of saline 10 ml with or without morphine 2 mg followed. Test drugs were administered through the IA catheter. Pain intensity and pain relief, consumption of rescue analgesics and global evaluation of effect and adverse effects were measured up to 36 h thereafter. RESULTS: Pain intensity decreased from about 50 to about 10-15/100 in both groups and the sum of pain intensity differences at 2 and 22 h was not significantly different between the two groups. Global evaluation of effects and adverse effects, as well as consumption of rescue analgesics during 36 h after arthroscopic procedures, were also similar in the two groups. CONCLUSIONS: Only 70% of 57 patients had pain of moderate-to-severe intensity within 1 h after an arthroscopic procedure of the knee joint under general anaesthesia. IA injection of saline 10 ml and saline 10 ml with morphine 2 mg were both associated with pain relief. These findings may have implications for interpretations of a majority of published studies on IA morphine.

Vitamin D deficiency and ovariectomy reduced the strength of the femoral neck in rats.

Vitamin D (vit D) deficiency is common in the elderly, and the aim of this study was to investigate whether vit D deprivation in ovariectomized (ovx) and normal rats would reduce fracture strength. Forty mature female Wistar rats were randomized into four groups: two were ovariectomized (ovx) and two were sham-operated (sham). One ovx and one sham group were fed a vit D-deficient diet (Ovx-D and Sham-D), and the control groups were fed normal rat chow (Ovx and Sham) for 12 weeks. Vit D deficiency was substantiated after 12 weeks by undetectable serum concentrations of 25OHD in the Sham-D and Ovx-D groups. 85Sr activity was lower in Sham-D than in the other groups (P < 0.005). Tibial and femoral weights and lengths showed no differences. Distal tibial trabecular bone volume was reduced in both ovx groups compare with sham (P < 0.005). Bone mineral density (BMD) was higher in sham than in Sham-D and both ovx groups (P < 0.005). Femoral area moment of inertia increased and ultimate stress decreased in Ovx-D compared with ovx (P < 0.05). Other biomechanical properties of the femoral shafts did not differ significantly. The femoral neck was significantly weaker in Ovx-D than in the other groups. In conclusion, ovx decreased tibial trabecular bone volume and both ovx and vit D depletion reduced femoral BMD in rats. Vit D depletion reduced the ultimate stress in the femoral shaft, and the combined depletion of estrogen and vit D significantly reduced the fracture strength in the femoral neck. This fits well with clinical evidence of how postmenopausal status combined with vit D deficiency lead to an increased risk of hip fractures, making this animal model a possible tool for investigating measures to prevent such fractures.

The normal development of tibial torsion.

OBJECTIVE: Pathological rotation of the leg is a well-known problem in paediatric orthopaedics. In this study the normal development of tibial torsion during growth was evaluated by computed tomography (CT). DESIGN: Seventy-eight normal individuals (52 children, 26 adults) aged 3-51 years were examined with CT. In axial scans the angle between a line tangential to the posterior part of the femoral condyles and the intermalleolar line, a line through the centre of the lateral and medial malleolus, was measured. The radiation exposure was evaluated and accepted by The National Department for Radiation and the Regional Committee for Ethics in Science. RESULTS: CT showed that the average lateral torsion of the leg at the age of 4 years was 28 degrees with an individual variation of 20 degrees-37 degrees. Later the increase in tibial torsion was on average 1 degrees/year until 10 years of age and, thereafter, 4 degrees until maturity when the mean lateral torsion was 38 degrees (18 degrees-47 degrees). CONCLUSION: Tibial torsion in children mainly develops during the first 4 years of life. After this the increase was of less clinical significance.

Deformation across the zone of callotasis during loading. radiostereometric analysis in a patient with achondroplasia.

The present study demonstrates that high-resolution radiostereometric analysis (RSA) can be used to assess global longitudinal compressive deformation across the callotasis zone during loading. In an achondroplastic patient operated with bifocal lengthening of the tibia by use of the Ilizarov external fixator, the axial compressive intersegmental strain in the proximal lengthening zone under a load of 71% of body weight was 7.7 mm. The proximal lengthening zone was 51.0 mm, and accordingly the overall linear strain across the callotasis was 15.1%. This large strain value found in distraction osteogenesis 6 weeks after end of distraction is not consistent with classical theory of the magnitude of micromotion needed for adequate stimulation of bone formation in fracture healing. The increased axial displacement did not stimulate bone healing and delayed union was observed. This one single observation does not allow for any conclusions to be drawn about the relationship of strain to fracture healing, but further and refined use of the RSA method will certainly improve our understanding of the role of axial strains in distraction osteogenesis.

Reduced tibial torsion in congenital clubfoot: CT measurements in 24 patients.

We determined leg torsion with CT scans through the femoral condyles and the ankle joints in 24 children (17 boys) with congenital clubfoot. In 16 cases, there was a bilateral clubfoot, in 5 cases it was left-sided and in 3 cases, it was on the right side. These children were compared to 17 healthy boys and 7 girls. The ages of all children ranged between 3 and 12 years. The average external torsion of the leg in the patients with clubfoot was 20 (15) versus 31 (7) degrees in the healthy children (p = 0.002). This study shows that there are great variations in leg torsion in children with congenital clubfoot and, on average, the external torsion is significantly lower than in healthy subjects.