Intermediate Dynamic Compression and Decreased Posterior Tilt With Interlocked Pins in Femoral Neck Fixation in Synthetic Bone.

Fixation failure with resulting non-union is the key complication after femoral neck fixation. It can be avoided by permitting dynamic compression and reducing rotation and posterior tilt of the femoral head. To achieve this, a novel implant that features an interlocking plate with three hook-pins (The Hansson Pinloc® System) was developed from the original two hook-pins. Only an enhanced torsional fixation by the implant modification is reported. The purpose was to compare the biomechanical compressive and bending stability of the original and modified implant in femoral neck fixation. To analyze the contribution of both modified components, three individual pins were included, although not in regular use. Forty-eight synthetic femurs with mid-cervical wedge osteotomies were fixated by two pins or identical triangular pin patterns with or without the plate. Eight specimens of each group were loaded cyclically in compression with an inferior wedge to simulate stance and anteroposterior bending with a posterior wedge to imitate sitting down. The clinically relevant stability measurements were stiffness and deformation. Fissure formation defined failure. The novel implant improved bending stability by 30% increased stiffness, 44% reduced deformation, and less frequent posterior neck fissure formation (p < 0.001) while increased compressive stability was only evident with 25% reduced deformation and less frequent inferior neck fissures (p < 0.001). These impacts were mainly mediated by the third pin, while the plate prevented a lateral fissure in compression (p < 0.001). The clinical stability was improved by dynamic compression and decreased posterior tilt by implant modification.

Increased stability by a novel femoral neck interlocking plate compared to conventional fixation methods. A biomechanical study in synthetic bone.

BACKGROUND: Stable fixation promotes union in the common femoral neck fractures, but high non-union rates due to fixation failure remain with traditional fixations. To enhance stability, a plate interlocking pins, but without further fixation to femur has been developed. To our knowledge, no comparison to other conventional fixation methods has been performed. We tested the hypothesis that the novel implant biomechanically leads to a more stable femoral neck fixation. METHODS: Fifty synthetic femurs with a cervical wedge osteotomy were allocated to intervention with three hook-pins interlocked in a plate (Hansson Pinloc® System) or standard fixations with a two-hole Dynamic Hip Screw® plate with an anti-rotational screw, three cannulated screws (ASNIS® III) or two screws (Olmed® or Cannulated Hip Screws®). Quasi-static non-destructive torsion around the neck, anteroposterior bending and vertical compression were tested to detect stiffness. The specimen's deformation was evaluated after cyclic compression simulating weight-bearing. Local deformation of implant channels was measured. Fixation failure was defined by fissure formation. FINDINGS: Compared to the conventional implants all together, the interlocked pins enhanced mean stiffness 130% in torsion and 33% in bending (P < 0.001), while compressive stability was increased by a reduced deformation of 62% in average of the global test specimen and 95% decreased local implant channel deformation after cycling (P < 0.001). In comparisons with each of the standard fixations the interlocking pins revealed no signs of adverse effects. INTERPRETATION: The novel femoral neck interlocking plate allowed dynamic compression and improved multi-directional stability compared to the traditional fixations.

The stabilising effect by a novel cable cerclage configuration in long cephalomedullary nailing of subtrochanteric fractures with a posteromedial wedge.

BACKGROUND: Clinical studies suggest that an adjunctive cerclage in intramedullary nailing of subtrochanteric fractures improves the outcome. Despite this, to what extent various cerclage configurations influences the fixation strength, remains undocumented. We tested the hypothesis that the stability of subtrochanteric fractures with a posteromedial wedge treated with long cephalomedullary nail varies with cerclage configuration. METHODS: 40 composite femurs with a subtrochanteric osteotomy including a posteromedial-wedge were locked by cephalomedullary nailing (T2 recon, Stryker) and divided into 4 groups. In Group-A no cerclage was applied. The Group-B received a lateral tension-band (cerclage cable with crimp, Depuy-Synthes). Without any fixation, the wedge-component was removed in these groups. The Group-C was fixed with a cerclage encircling the wedge-component, while in the Group-D a novel figure-of-8 cerclage stabilised the wedge-component. Each femur was tested quasi-static in a material-testing-machine for stiffness calculation, first horizontally to simulate seated-position and then vertically to simulate standing-position. Finally, cyclic testing was performed in the upright-posture to measure deformation over time. FINDINGS: In Group-D the mean stiffness in the sitting-position was 6.4, 5.8 and 3.1 times higher than the Groups-A, B and C, respectively, and correspondingly 2.0, 2.1 and 1.7 times higher in the standing-position (p < 0.05). Over time, Group-D demonstrated less mean deformation than tension-band (p = 0.05), while the deformation was not significantly different from the other groups. INTERPRETATION: Additional use of cerclage enhances the stability of intramedullary nailed subtrochanteric fractures, and use of the figure-of-8 cerclage configuration, compressing the entire posteromedial-buttress, is the superior technique.

High correlation between mechanical properties and bone mineral parameters in embalmed femurs after long-term storage.

BACKGROUND: Fresh frozen human femurs are considered "the gold standard" in biomechanical studies of hip fractures, resembling the in vivo situation mostly. A more readily available alternative is formalin embalmed femurs. However, to which extent formalin affects key features of bone; its mechanical properties, bone mineral content and their mutual relationship over time, remains unknown. Accordingly, we measured the mineral parameters and related them to the mechanical properties of formalin fixed femurs after long-term storage. METHODS: 36 paired femurs from human donors, fixed in formalin and stored for a mean period of 4.6 (3.5-6) years. Quantitative CT was performed to measure the bone mineral density and mass at the mainly cortical mid shaft and the center of the mainly cancellous condyles. Each pair was subjected to local tests by three-point bending and screw pullout of the shaft and lateral punch and metaphyseal cube compression of the condyles. FINDINGS: Neither mechanical nor bone mineral data were significantly correlated to storage time. Well-known associations for bone parameters with age and gender were retrieved. Maximum force of the cortical bone tests was highly correlated to the diaphyseal bone mass; (r = 0.80-0.87, p = 0.01), while maximum force of the cancellous bone tests correlated well to the density of the condylar bone; (r = 0.70, p = 0.01). INTERPRETATION: Our results indicate that mechanical and bone mineral data and their mutual relationship are conserved in formalin fixed femurs even after long-term storage. Formalin fixed femurs may serve as an alternative to fresh frozen femurs in biomechanical testing.

Increased torsional stability by a novel femoral neck locking plate. The role of plate design and pin configuration in a synthetic bone block model.

BACKGROUND: In undisplaced femoral neck fractures, internal fixation remains the main treatment, with mechanical failure as a frequent complication. As torsional stable fixation promotes femoral neck fracture healing, the Hansson Pinloc® System with a plate interlocking pins, was developed from the original hook pins. Since its effect on torsional stability is undocumented, the novel implant was compared with the original configurations. METHODS: Forty-two proximal femur models custom made of two blocks of polyurethane foam were tested. The medial block simulated the cancellous head, while the lateral was laminated with a glass fiber filled epoxy sheet simulating trochanteric cortical bone. Two hollow metal cylinders with a circumferential ball bearing in between mimicked the neck, with a perpendicular fracture in the middle. Fractures were fixated by two or three independent pins or by five configurations involving the interlocking plate (two pins with an optional peg in a small plate, or three pins in a small, medium or large plate). Six torsional tests were performed on each configuration to calculate torsional stiffness, torque at failure and failure energy. FINDINGS: The novel configurations improved parameters up to an average of 12.0 (stiffness), 19.3 (torque) and 19.9 (energy) times higher than the original two pins (P < 0.001). The plate, its size and its triangular configuration improved all parameters (P = 0.03), the plate being most effective, also preventing permanent failure (P < 0.001). INTERPRETATION: The novel plate design with its pin configuration enhanced torsional stability. To reveal clinical relevance a clinical study is planned.

Micronutrients and the risk of hip fracture: Case-control study.

BACKGROUND: Vitamin D, and possibly vitamin K, has an established association to fracture risk. Other vitamins are, however, less studied. AIM: To determine whether specific micronutrients other than 25(OH)D and vitamin K play a role in risk of hip fracture and bone turnover. METHODS: In this case-control study, blood was drawn for measurements of vitamins A, B6, B12, C, E, and folic acid as well as the bone turnover markers osteocalcin and bone-specific alkaline phosphatase upon admission for hip fracture in 116 patients and in 73 home-dwelling non fractured controls. Results for vitamin K1 and 25(OH)D from the same populations have been reported previously. RESULTS: Low vitamin A, C, and E concentrations were independently associated with a risk of hip fracture. The adjusted odds ratio (95% confidence interval) per 10 µmol/L increase in vitamin A concentration was 0.74 (0.65-0.84); for 1 µmol/L vitamin C and E: 0.94 (0.92-0.97) and 0.81 (0.74-0.89) respectively. The results were principally unchanged when 25(OH)D, vitamin K1, Body Mass Index, and other potential confounders were adjusted for. All vitamins except B12 and folic acid correlated positively with total osteocalcin and negatively with bone-specific alkaline phosphatase. CONCLUSIONS: Low vitamin A, C, and E concentrations are associated with an increased risk of hip fracture, possibly mediated through bone turnover mechanisms. This case-control study is registered at: ClinicalTrials.gov. NCT01738776. The patient related outcome is also registered at: ClinicalTrials.gov. NCT01009268.

Vitamin K1 and 25(OH)D are independently and synergistically associated with a risk for hip fracture in an elderly population: a case control study.

BACKGROUND & AIMS: The incidence of hip fractures in Oslo is among the highest in the world. Vitamin D, as well as vitamin K, may play an important role in bone metabolism. We examined if vitamin K1 and 25(OH)D were associated with an increased risk of hip fracture, and whether the possible synergistic effect of these two micronutrients is mediated through bone turnover markers. METHODS: Blood was drawn for vitamin K1, 25(OH)D, and the bone turnover marker osteocalcin upon admission for hip fracture and in healthy controls. RESULTS: Vitamin K1 and 25(OH)D were independently associated with a risk of hip fracture. The adjusted odds ratio (95% CI) per ng/ml increase in vitamin K1 was 0.07 (0.02-0.32), and that per nmol/L increase in 25(OH)D was 0.96 (0.95-0.98). There was a significant interaction between 25(OH)D and vitamin K1 (p < 0.001), and a significant correlation between total osteocalcin and vitamin K1 and 25(OH)D (rho = 0.18, p = 0.01; rho = 0.20, p = 0.01, respectively). CONCLUSIONS: Vitamin K1 and 25(OH)D are lower in hip fracture patients compared with controls. Vitamin K1 and 25(OH)D are independently and synergistically associated with the risk of hip fracture when adjusting for confounders. Intervention studies should include both vitamins.

Nonoperative treatment of the medial malleolus in bimalleolar and trimalleolar ankle fractures: a randomized controlled trial.

OBJECTIVES: To compare internal fixation with no fixation of the medial malleolus after open reduction and internal fixation of the lateral malleolus and if needed, the posterior malleolus. DESIGN: Randomized prospective trial. SETTING: Level III trauma center in a metropolitan area. PATIENTS: One hundred patients with bimalleolar or trimalleolar Orthopaedic Trauma Association type 44 ankle fractures and displacement of the medial malleolus less than 2 mm after open reduction and internal fixation of the lateral component. INTERVENTION: Internal fixation or nonoperative treatment of the medial malleolus. MAIN OUTCOME MEASUREMENTS: American Orthopaedic Foot and Ankle Society ankle hind foot score (AOFAS), The Olerud Molander Ankle (OMA) score, and visual analogue pain scale (VAS). RESULTS: Median follow-up time was 39 months (range: 24-72). There were no significant differences between the 2 groups with respect to OMA (P = 0.91), AOFAS (P = 0.85), VAS (P = 0.85), or development of osteoarthritis (P = 0.22). Reoperation and complication rates were also comparable, but 4 patients treated nonoperatively developed nonunion of the medial malleolus. These patients reported no functional disabilities and presented OMA, AOFAS, and VAS scores better than average. CONCLUSIONS: Our data indicate that nonoperative treatment of minimally displaced fractures of the medial malleolus after operative fixation of the fibula yields satisfactory results. However, long-term follow-up is needed due to increased risk of nonunion and uncertainty regarding the development of posttraumatic arthritis. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Failed internal fixation of femoral neck fractures.

BACKGROUND: There are two types of surgical treatment for fractures of the femoral neck; internal fixation and arthroplasty. Internal fixation is associated with a higher risk of complications such as secondary displacement, non-union and avascular necrosis. To improve treatment results of internal fixation, we have tried to identify procedure related risk-factors associated with fixation failure. MATERIAL AND METHOD: A retrospective study was conducted based on the medical records and X-ray images of 337 patients sustaining intracapsular fractures of the hip during the period 1999-2000. The patients were treated with closed reduction and internal fixation at Oslo University Hospital, Aker. The reduction of the fracture and the placement of the fixation implants were evaluated and scored (six points representing best achievable result). RESULTS: Fixation failed in 23 (18,3 %) out of 126 patients with displaced fractures awarded six points for the reduction. In contrast, fixation failed in five (50 %) out of ten patients given a score of three points or less (p = 0.017). The risk of non-union increased when patients were treated more than 48 hours after the initial injury. In this group, 5 (25 %) out of 20 patients developed non-union compared to 16 (8 %) out of 200 patients treated within 48 hours (p = 0.014). INTERPRETATION: Our findings emphasize the importance of achieving anatomical reduction of displaced femoral neck fractures, and to perform surgery within 48 hours unless an acute medical condition needs to be stabilized.

Surgical treatment with an angular stable plate for complex displaced proximal humeral fractures in elderly patients: a randomized controlled trial.

OBJECTIVE: The objective of the study was to evaluate functional outcome, patient self-assessment, and radiographic outcome at 1 year in displaced three- and four-part proximal humeral fractures (OTA group 11-B2 and 11-C2). DESIGN: Randomized controlled trial. SETTING: Academic medical center. PATIENTS/PARTICIPANTS: Fifty patients aged 60 years or older with displaced three- or four-part proximal humeral fractures and no previous shoulder injuries were randomized either to surgical treatment or to conservative closed treatment. Twenty-five patients were included in each group. Forty-eight patients completed 12-month follow-up. Two surgical patients died within 3 months. INTERVENTION: The surgically treated group had a standardized surgical treatment with open reduction and internal fixation using an angular stable plate and cerclages. Instructed physical therapy started the third postoperative day. The conservative treatment group had a standardized nonoperative treatment that included closed reduction if displacement between the head and metaphyseal shaft fragment exceeded 50% of the diaphyseal diameter. Physical therapy started on the fifteenth postoperative day. MAIN OUTCOME MEASUREMENTS: The main outcome was the mean difference in Constant score between the injured and noninjured shoulder at 12 months. The secondary outcomes were patient self-assessment (American Shoulder and Elbow Surgeons score) and radiographic ratings at 12 months. RESULTS: At 12 months, mean Constant scores favored conservative treatment by 2.4 points (nonsignificant; P = 0.62). There was no significant difference in mean patient self-assessment. However, radiographic outcomes were significantly better for surgically treated patients. CONCLUSION: There is no evidence of a difference in functional outcome at 1-year follow-up between surgical treatment and conservative treatment of displaced proximal humeral fractures in elderly patients.

Rotator cuff tears in proximal humeral fractures: an MRI cohort study in 76 patients.

BACKGROUND: The aim was to evaluate if concomitant injury to the rotator cuff is important for functional outcome in proximal humerus fractures, and to relate loss of function to malunion of the fractures. MATERIALS AND METHODS: A total of 76 patients treated conservatively for proximal humerus fracture were included in this cohort study. Performing an MRI: examination at the time of injury and after 12 months, tears of the rotator cuffs were classified as partial- or full thickness. The fractures were classified, according to the AO classification, and the degree of tubercle displacement and humeral head inclination evaluated at 12 months. Constant score was used as outcome measure. RESULTS: Magnetic resonance imaging (MRI) examinations confirmed 22 rotator cuff tears (four full thicknesses) diagnosed at the time of injury, and 10 additional tears (three full thicknesses) at one year. Functional loss at one year significantly corresponded to the tears at the time of injury (P = 0.004), varus malunion of the head and displacement of tubercles (P < 0.001). INTERPRETATION: Partial- as well as full thickness tears of the rotator cuff are important for functional outcome. Skeletal deterioration seems even more important.

Edema in the lower limb of patients operated on for proximal femoral fractures.

BACKGROUND: Patients with proximal femoral fracture (PFF) often develop postoperative edema in the operated limb. This may lead to reduced mobilization, increasing the length of hospitalization. It is therefore relevant to gain information about the extent and pathogenesis of this edema formation. METHODS: Forty-one patients with PFF (30 women and 11 men) were studied pre- and postoperatively. Patients were grouped into pertrochanteric fractures and femoral cervical fractures, according to the AO/ASIF classification of PFF. Thigh and calf volumes were calculated in both fractured and contralateral limbs preoperatively and on postoperative days 3, 5, 7, and 30. RESULTS: All patients with PFF developed edema in the operated limb. The greatest volume increase occurred on postoperative day 7 (p < 0.0005). The magnitude of edema in the thigh and the leg of patients with pertrochanteric fractures as compared with the nonoperative side was approximately twice as great as in those with femoral cervical fractures (p < 0.0001). There was a statistically significant daily increase in the volume of the operative limb as compared with the nonoperative side. Age and sex were not correlated with the extent of edema formation. Functionally significant deep venous thrombosis and local infection could be excluded as causative factors. CONCLUSIONS: Postoperative edema in the thigh and leg of the operated limb was considerable. The magnitude of edema formation was related to the severity of primary trauma and the type of osteosynthesis. Therefore, the operation performed for PFF should be minimally traumatic.

Fractures in the proximal humerus: functional outcome and evaluation of 70 patients treated in hospital.

INTRODUCTION: Patients with proximal humeral fractures are mostly elderly. In addition to the proximal humeral fracture, they often have other injuries related to poor bone quality. The surgical treatment of proximal humeral fractures in elderly patients with comminuted fractures is associated with several problems and a high frequency of complications. The aims of this study were to evaluate patients with a proximal humeral fracture treated in a hospital, assess the outcome of the fracture treatment, and decide whether surgical treatment of displaced proximal humeral fractures is superior to conservative treatment or not. MATERIALS AND METHODS: Patients with fractures of the proximal part of the humerus treated in our hospital were followed during two different periods (14 and 10 months). The study in the first time period was retrospective in design, while in the second period the patients were followed prospectively. Seventy patients, (71% women) with a mean age of 71 years, were included in the study. A functional test was performed within 12-14 months after the injury using a modified Rowe shoulder score. Surgical treatment was performed in 15 patients (21%). Neither the surgical approach nor the implants used for osteosynthesis were standardized. Fifty-five patients (79%) were treated conservatively with a modified Velpeau bandage or a sling. RESULTS: The fractures were classified according to AO into type A (27%), type B (58%) and type C (14%). Osteoporotic risk factors were present in many of the patients, mainly characterized by other skeletal injuries than the proximal humeral fracture (43%). In the group of complex, displaced, non-impacted fractures B2, B3, C2, C3 included (20 fractures), the group treated conservatively had a mean Rowe score of 48/75 (64% of maximum score) and SD 16.8, while in the surgically treated group the mean score was 28/75 (38% of maximum score) and SD 8.1. The difference between the two treatments was significant, with a p-value of 0.01 in favour of the conservatively treated group. CONCLUSION: The number of patients in each of the fracture groups was low, but surgery did not benefit the patients with complex, displaced fractures in this study.

Tricortical versus quadricortical syndesmosis fixation in ankle fractures: a prospective, randomized study comparing two methods of syndesmosis fixation.

OBJECTIVE: To assess short-term functional results in 2 types of syn-desmotic fixation, comparing the traditional rigid quadricortical syndesmotic screw fixation with a more dynamic tricortical screw fixation. DESIGN: : Prospective, randomized clinical study. SETTING: University clinic, level 1 trauma center. PATIENTS: Sixty-four patients with closed ankle fractures in which the syndesmosis was found to be unstable intraoperatively. INTERVENTION: The unstable syndesmoses were fixed with either one 4.5-mm cortical screw through both tibial cortices (n = 30) or two 3.5-mm cortical screws engaging only 1 cortex of the tibia (n = 34). The quadricortical screws were routinely removed after 2 months, whereas the tricortical screws were removed only in the case of discomfort. Rehabilitation was the same in both groups. RESULTS: The Olerud Molander functional score (0-100) was significantly higher in the tricortical group (77 points) compared with the quadricortical group (66 points) (P = 0.025) at 3 months. After 1 year, however, the functional score was not significantly higher (P = 0.192) in the tricortical group (92.6 points) compared with the quadricortical group (85.7 points). Pain was significantly lower in the tricortical group (P = 0.017) after 3 months, but there was no significant difference after 1 year. There was no significant difference in dorsiflexion between the groups at any point of time. No losses of fixation were detected. The tricortical screws were removed in 2 patients due to migration. CONCLUSIONS: Syndesmosis fixation with 2 tricortical screws is safe and improves early function. After 1 year, however, there were no significant differences between the 2 groups in functional score, pain, and dorsiflexion.

Fracture fixation problems in osteoporosis.

Osteoporosis, or loss of bone mass and microarchitectural deterioration of bone tissue, does not only enhance risk of fracture but also represents a problem in osteofixation of fractures in fracture treatment. Aging of the western population changes the epidemiology of fractures. An increasing socioeconomic interest in geriatric traumatology makes the need for much urgent study in the field of osteoporotic fractures self evident. It is no longer the province of only one medical group to look for fragmented solutions in the treatment of osteoporotic fractures. Efforts have to be united across professional boundaries to meet the challenge of this problem. Assessment of bone mineral may be used in evaluation of fracture risk but also in the choice of implant as well as in the design of implants used in fracture treatment. The differences in mechanical properties of different types of bone in the same individual have to be respected. Changes in the pattern of fractures and problems with implant anchorage in bone, due to a demographic increase in patients with osteoporosis remain problems requiring new solutions. Still basic principals in fracture treatment may not be eclipsed by new fixation devices.