Interlocked Pins Increase Strength by a Lateral Spread of Load in Femoral Neck Fixation: a Cadaver Study.

PURPOSE OF THE STUDY To improve the important torsional, bending and compressive stability in femoral neck fixation, locking plates have been the latest contribution. However, increased strength by restricted fracture motion may come at expense of an altered load distribution and failure patterns. Within locking plate technology, the important intermediate fracture compression may principally be achieved by multiple sliding screws passing through a sideplate fixed to the femur or connected to an interlocking plate not fixed to the femur laterally, sliding "en bloc" with the plate. While biomechanical studies may deliver the short-time patient safety requirements in implant development, no adequate failure evaluation has been performed with interlocking devices ex vivo in this setting. In the present biomechanical study, we analysed if a novel femoral neck interlocking plate with pins could improve fixation performance by changing the parameters involved in the failure mechanism in terms of fixation strength, fracture motion, load distribution and failure pattern. MATERIAL AND METHODS Sixteen pairs of human femurs with stable subcapital osteotomies were fixated by 2 pins or 3 pins interlocked in a plate using a paired design. Femurs were loaded non-destructively to 10° torsion around the neck axis, 200 N anteroposterior bending and 500 N vertical compression in 7° adduction with 1 Hz in 20 000 cycles, and were subsequently subjected to destructive compression to evaluate failure patterns. Bending stiffness, compressive stiffness and displacement from compressive testing reflected fracture motion. Torque and compression to failure replicated known failure mechanisms and defined strength. To evaluate load distribution, associations between biomechanical parameters and measured local bone mineral measurements by quantitative CT were analysed. RESULTS Interlocked pins increased mean strength 73% in torsion and 39% in compression (p = 0.038). Strength was related to all 4 regional mineral masses from the femoral head to subtrochanterically with interlocking (r = 0.64-0.83, p = 0.034), while only to mineral masses in the femoral head in compression and to the head, neck and trochanterically in torsion with individual pins (r = 0.67-0.78, p = 0.024). No difference was detected in fracture motion or failure pattern. DISCUSSION Within the last decade, angular stable implants have expanded our therapeutic arsenal of femoral neck fractures. Increased stability at the expense of altered devastating failure patterns was not retrieved in our study. The broadened understanding of the effect of interlocking pins by an isolated plate as in the current study involved the feature to gain fixation strength. By permitting fracture compression, and through a significant change of correlations between mechanical parameters and local bone mineral factors, a lateral redistribution of load with interlocked pins from the fragile bone medially to the more solid lateral bone was demonstrated. Regarding the long-term patient safety of interlocked pins and healing complications of non-union and segmental collapse of the femoral head, a definite conclusion may be premature. However, the improved biomechanics of an interlocking plate must be considered a favourable development of the pin concept. CONCLUSIONS Interlocked pins may improve fixation performance by a better load distribution, not by restricting fracture motion with corresponding altered failure patterns. This is encouraging and a challenge to complete further studies of the interlocking plate technology in the struggle to find the optimal treatment of the femoral neck fracture. Key words: femoral neck fracture, biomechanics, cadaver bone, bone mineral, internal fixation, locking plate, interlocked pins.

Health and cost consequences of surgical versus conservative treatment for a comminuted proximal humeral fracture in elderly patients.

OBJECTIVE: This study aims to evaluate the costs and health outcome for surgical and conservative treatment of displaced proximal humeral fractures. DESIGN: This study is a randomised controlled trial. PARTICIPANTS: This study included 50 patients aged 60 or older admitted to hospital with a severely displaced three- or four-part fracture. INTERVENTIONS: The patients were treated surgically with an angular stable interlocking implant (25 patients) or conservative treatment (25 patients). MAIN OUTCOME MEASURE: The outcomes measured included quality-adjusted life years (QALYs) and societal costs. RESULTS: At 12 months' follow-up, the mean difference in the number of QALYs was 0.027 (95% confidence interval (CI)=-0.025, 0.078) while the mean difference in total health-care costs was 597 euro in favour of surgery (95% CI=-5291, 3777). CONCLUSION: There was no significant difference in QALYs or costs between surgical and conservative treatment of severe displaced proximal humeral fractures.

Soft tissue problems in ankle fractures treated surgically. A prospective study of 154 consecutive closed ankle fractures.

We performed a prospective registration of primary soft tissue injuries and perioperative soft tissue complications the first 3 months after surgery in ankle fractures treated by open reduction and internal fixation. Open fractures and polytraumatized patients were excluded. The 154 consecutive patients (90 women) with an average age of 54.5 (S.D. 18.3) years were registered. Primary soft tissue injuries according to Tscherne's classification were noted in 22 patients (14.2%). Major perioperative soft tissue complications requiring revision occurred in five patients (3.2%). Minor perioperative soft tissue complications treated non-operatively occurred in 29 patients (18.8%). A significantly higher incidence of perioperative soft tissue complications occurred in alcohol abusers (P=0.043), after high-energy trauma (P=0.043), and after primary soft tissue injuries (P=0.004). Other possible risk factors such as age, gender, fracture type, diabetes, arteriosclerosis, coronary heart disease, and hypothyroidism had no statistically significant influence on the incidence of perioperative soft tissue complications.

Fixation of fractures of the femoral neck. A prospective, randomised trial of three Ullevaal hip screws versus two Hansson hook-pins.

In a prospective, randomised trial, we compared the use of three Ullevaal hip screws with that of two Hansson hook-pins in 278 patients with fractures of the femoral neck. Background factors were similar in both groups. Follow-up was for two years. There were no significant differences between the groups in length of time of surgery, hospital stay, general complications, mortality, pain or walking ability. Likewise, the rates of early failure of fixation, nonunion, and the need for reoperation did not differ significantly between the groups. The use of hook-pins was associated with less drill penetrations of the femoral head during surgery (odds ratio 2.6, p = 0.05) and a lower incidence of necrosis of the femoral head (odds ratio 3.5, p = 0.04). There was a strong relationship between poor reduction and fixation of the fracture and subsequent reoperation (p = 0.0005 and p = 0.0001, respectively). Likewise, peroperative drill penetration of the femoral head was associated with a greater risk of reoperation (p = 0.038). Both methods gave favourable results. In total, 22% of the patients needed a major reoperation (usually hemiarthroplasty), while in 7% of the cases the fixation device needed to be removed. Osteosynthesis as the sole method for operation of all fractures of the femoral neck was thus successful in 78% of patients. With selective treatment most of the remaining patients would have benefited if treated by a primary arthroplasty. Accurate selection requires the development of better prognostic methods.

The influence of perioperative soft tissue complications on the clinical outcome in surgically treated ankle fractures.

The influence of perioperative soft tissue complications on the functional outcome after open reduction and internal fixation of closed ankle fractures was investigated. Eighty-eight consecutive patients were followed 3.7 years (SD +/- 0.6) after the injury. Two major and 21 minor soft tissue complications were registered. Average dorsal extension was 29.9 degrees (range four to 54, SD +/- 9.5) of the fractured ankles and 37.2 degrees (range eight to 60, SD +/- 9.1) of the non-fractured ankles. The average subjective functional score was 84.6 (range 40 to 100, SD +/- 14.9). A significant difference was found with respect to the subjective functional score (p = 0.048, Kruskal-Wallis test) but not with respect to dorsal extension (0.358, Kruskal-Wallis test) when comparing groups of minor, major and no soft tissue complications. This study suggests that major soft tissue complications have a negative effect on the long-term functional outcome after surgical repair of an ankle fracture. Minor soft tissue complications, primary skin problems, the timing of primary surgery and fracture types according to AO/ASIF have no or minor influence on the long-term functional result. This study confirms previous reports that the presence of osteoarthritis is frequently associated with a reduced functional outcome.

Functional results of braced humeral diaphyseal fractures: why do 38% lose external rotation of the shoulder?

A total of 67 humeral diaphyseal fractures treated with functional bracing was studied. The median follow-up was 30 weeks. Sixty-one fractures (91%) healed and 6 fractures (8.9%) progressed to non-unions. Fifty-four fractures could be functionally classified according to a modified Wasmer score. Pain, range of motion in the shoulder and elbow, and changes in activities of daily life were recorded. Loss of external rotation in the shoulder was most prominent, being present in 21 (38%) of the fractures. To evaluate the cause of loss of external rotation, 21 of the patients were selected for two groups to be studied with computed tomography (CT). Twelve patients had normal clinical findings without a loss of external rotation, while 9 patients had subnormal external rotation in the shoulder of the injured limb. Fracture consolidation in malrotation was seen frequently, and a linear correlation between the clinical loss of external rotation and CT findings was indicated, but no statistical agreement could be proved. The time between injury and brace application could possibly contribute to consolidation in malrotation.

The influence of the timing of surgery on soft tissue complications and hospital stay. A review of 84 closed ankle fractures.

BACKGROUND AND AIMS: Open reduction and internal fixation of an extensively swollen ankle may lead to wound closure problems, blistering, wound edge necrosis and infection. Accordingly, internal fixation should be accomplished either before or after the period of critical soft tissue swelling. The object of the study was to investigate if the timing of surgery had any influence upon soft tissue complications and hospital stay. PATIENTS AND METHODS: The clinical course of the first 6 postoperative weeks of 84 closed ankle fractures treated by open reduction and internal fixation were reviewed. Seventeen patients were not operated on early due to lack of operative capacity and were thus operated on after 5 days or more. These patients were compared to the patients operated on within 8 hours (n = 67). The groups were comparable with respect to age, gender and fracture types. RESULTS: Despite a higher incidence of primary soft tissue injuries in the early group, the patients operated on delayed had a higher incidence of wound infections (17.6% vs. 3.0%) and hospital stay was prolonged with 12.4 days compared to early surgery. All wound infections were found in grossly displaced fractures despite adequate closed reduction immediately after arrival in the hospital. CONCLUSIONS: Delayed surgery of closed ankle fractures increases the risk of soft tissue complications and prolongs hospital stay. Immediate surgery is particularly indicated in the severely displaced ankle fracture, and if not achievable, temporary reduction and immobilization is recommended.

Open reduction and internal fixation in flexion-distraction injuries to the lower spine in children and adolescents involved in traffic accidents as car occupants. A report and literature review.

Flexion-distraction injuries of the spine are reported after traffic accidents in individuals wearing only lap seatbelts. We examine here this type of injury in one child and two adolescents who all were seated in the rear seat of cars involved in traffic accidents. All of the children were wearing regular three-point safety belts not adjusted to children. They were all treated surgically. Two of the patients had no neurological impairment, while one patient suffered persistent complete paraplegia. In two patients intra-abdominal lesions required surgery. Flexion-distraction injuries in individuals with an immature skeleton, wearing standard three-point safety belts, have not been reported in the literature. The pathomechanism of the lesion in the lower spine may well involve damage to the intestines, particularly at the junction between the mobile intra-abdominal and the fixed retroperitoneal part of the gut. Reduction and stable fixation preserve the anatomy of the lower spine, while unstable fixation methods do not secure reduction sufficiently to allow early mobilisation.

Early complications of surgically managed ankle fractures related to the AO classification.A review of 118 ankle fractures treated with open reduction and internal fixation.

The charts of 118 consecutive ankle fractures were reviewed. The patients' age, sex, energy of trauma, hospital stay, need for traction therapy, syndesmosis fixation and soft-tissue problems were related to the various types of fractures according to the AO classification. An interobserver check study revealed an agreement of 0.61 (kappa), which is considered good. The age of the patients with A-fractures was 33 years (SD +/- 13), B-fractures 56 years (SD +/- 18), and C-fractures 48 years (SD +/- 16). The age differences within these groups were highly significant (P < 0.005). The highest average ages were found in the patients with B2 and B3 type fractures, 57 and 61 years, respectively. Women were significantly older than men (P < 0.0001), and 61% of the patients were women. Perioperative problems, such as wound margin necrosis and infections, were significantly related to fracture types B2 and B3. Preoperative traction therapy was necessary in the least stable fractures, of which all but one C1 fracture were B2/3 type fractures. The energy of trauma was not related to perioperative problems. The period of hospitalisation was significantly longer in the patients with B2/B3 type fractures (P < 0.001). Judging by the significantly higher incidence of perioperative complications, longer hospital stay, and predominance of instability and skin damage in the AO B2 and B3 type fractures, these fractures may benefit from more attentive and urgent care.

[Miniinvasive plate osteosynthesis of distal tibial fractures]. / Miniinvasiv plateosteosyntese av distale brudd i tibia.

The end result after open reduction and internal fixation in distal leg fractures is jeopardized by soft tissue complications. Functional conservative treatment of the same type of fractures often results in delayed and non-union, malunion or non-optimal functional result concerning ankle mobility. Mini-invasive plateosteosynthesis was performed in ten patients with sustained juxta or intra-articular fractures of the distal tibia. In all patients, stable osteo-fixation could be achieved and soft tissue complications did not affect the final result in any of the patients. Mini-invasive plateosteosynthesis seems to be a good treatment alternative in extra- or intraarticular fractures of the distal leg.

Compartment pressure in nailed tibial fractures. A threshold of 30 mmHg for decompression gives 29% fasciotomies.

During the past few years we have monitored tissue pressure in patients treated with intramedullary nailing of tibial shaft fractures. A value of 30 mmHg has been used as the threshold for fasciotomy. The purpose of this study was to evaluate this practice. Sixty-three patients were included in the series. Forty-three fractures were closed, 18 grade I (Gustilo) and two grade II. Tissue pressure measurements were performed in 43 patients. Eighteen legs were treated with decompressive fasciotomy, three on clinical findings alone, and 15 after measurement of a pressure higher than 30 mmHg. This gives a fasciotomy rate of 29%. At follow-up two patients were dead. All fractures were healed, and there were no major complications such as deep infection, extensive muscle necrosis, paresis or short-foot syndrome. Three fasciotomized patients had significantly reduced muscle strength compared with the contralateral leg.

Open reduction and internal fixation in 46 displaced intraarticular calcaneal fractures.

The subject of this report is the evaluation of 46 comminuted displaced intraarticular calcaneal fractures in 40 patients treated by open reduction and internal fixation. The results were validated by a score based on objective findings and a subjective gradation obtained by a visual analyzing score (VAS). The results were excellent or good in 30 treated fractures, while the results in 9 fractures were validated a satisfactory and in 7 as unsatisfactory. The results concerning disability and need for workman's compensation were promising in patients who had suffered fractures known to result in a high disability and compensation rate.

Dynamic hip screw with trochanteric stabilizing plate in the treatment of unstable proximal femoral fractures: a comparative study with the Gamma nail and compression hip screw.

OBJECTIVE: To compare the results after operative treatment of unstable per- and subtrochanteric fractures with the Gamma nail, compression hip screw (CHS), or dynamic hip screw with a laterally mounted trochanteric stabilizing plate (DHS/TSP). DESIGN: Prospective. PATIENTS: One hundred seventy patients with unstable trochanteric femoral fractures surviving six months after operation. Eighty-five patients were randomized to treatment with the Gamma nail (n = 50, Gamma group) or the compression hip screw (n = 35, CHS group) and compared with a consecutive series of eighty-five patients operated with the dynamic hip screw with a laterally mounted trochanteric stabilizing plate (DHS/TSP group) MAIN OUTCOME MEASUREMENTS: Radiographs were analyzed for fracture classification, evaluation of fracture reduction, implant positioning, later fracture dislocation, and other complications. Pre- and postoperative functional status of the patients were recorded, with a minimum of six months follow-up. RESULTS: Eighteen percent of the patients in the Gamma group, 34 percent in the CHS group, and 9 percent in the DHS/TSP group suffered significant secondary fracture dislocation during the six months follow-up, leading to a varus malunion, lag screw cutout, or excessive lag screw sliding with medialization of the distal fracture fragment. Two patients (4.0 percent) in the Gamma group suffered an implant-related femoral fracture below the nail, and one had a deep infection. The reoperation rates were 8.0 percent in the Gamma group, 2.9 percent in the CHS group, and 5.9 percent in the DHS/TSP group. All but one fracture in the Gamma and CHS groups and two fractures in the DHS/TSP group healed within six months. Approximately three-fourths of the patients had returned to their preoperative walking ability after six months, with a trend toward better functional outcome in the DHS/TSP group. Use of a TSP reduced the secondary lag screw sliding as compared with the conventional CHS, without affecting fracture healing. CONCLUSION: The TSP may be an aid in the treatment of these difficult fractures because the problem with femoral shaft fractures using the Gamma nail is avoided and the medialization of the distal fracture fragment frequently associated with the CHS is prevented.

Unstable vertebral fractures in the lower third of the spine treated with closed reduction and transpedicular posterior fixation: a retrospective analysis of 82 fractures in 78 patients.

Seventy-eight patients were treated with closed reduction and transpedicular fixation for 82 spine fractures. The fractures were localised in the lower third of the spine and were all, according to the Denis classification, considered unstable. Eighteen patients had neurological deficiencies. One patient with a fracture in T11 was completely paraplegic, four patients had a cauda equina syndrome while the rest had radicular symptoms only. Primary reconstruction of the vertebral height and the physiological curves of the spine was satisfactorily obtained. An improvement in the neurological symptoms was observed in all patients with fractures distal to the spinal cord, while the patient with the dislocated fracture of T11 remained completely paraplegic during the follow-up. The complication rate of the transpedicular fixation method used reported by other authors could not be confirmed in our material. Iatrogenic neurological damage was not observed. A partial loss in the correction of the traumatic kyphosis was observed after removal of the implant in 11 patients.

[Transiliacal screw fixation of the sacrum in unstable pelvic ring fractures]. / Transiliakal skruefiksasjon av sacrum ved ustabile bekkenringbrudd.

This article presents our experiences from fixation of the sacrum by transiliacal screw in 13 patients with unstable fractures of the pelvic ring. Early mobilization, with no secondary dislocation or postoperative complications, was achieved in all patients. Sagittal instability in unstable pelvic ring fractures must be acknowledged. The transiliac screw offers the possibility of early mobilization of patients with this fracture. The procedure is demanding and patients selected for this treatment should be referred to hospitals with experience in the treatment of pelvic fractures.

The repair of a ruptured deltoid ligament is not necessary in ankle fractures.

We randomised 50 patients with ankle fractures of Weber types B and C and a ruptured deltoid ligament treated by open reduction and internal fixation to two treatment groups to examine the influence of the repair of a ruptured deltoid ligament. No differences were found except for a longer duration of surgery in the repair group. Our findings suggest that a ruptured deltoid ligament can be left unexplored without any effect either on early mobilisation or on the long-term result.

Bending strength of the femur in relation to non-invasive bone mineral assessment.

To analyze the importance of bone mineral for the strength of the distal diaphyseal femur, we studied 14 distal cadaver femora by quantitative computed tomography, (QCT) dual energy X-ray (DXA) absorptiometry and three-point bending. The femora were retrieved at autopsy from 10 male and 4 female donors aged median 74 yr (range 59-92 yr). Significant correlations were found between three bone mineral mass related parameters--QCT bone mass (density x slice area), DXA mineral density (BMD) and content (BMC)--and mechanical parameters. Second area moment equivalents correlated significantly with the mechanical properties of the distal femur. QCT density did not show the same high correlations. The results indicate that the structural strength of diaphyseal bone is determined more by its geometry than mineral density. Assessment of bone mass by QCT or DXA may become important not only for assessment of fracture risk but also for planning of internal fixation in the treatment of osteporotic fractures. Further studies are required to investigate the clinical importance of these observations.

[Compartment pressure after intramedullary fracture nailing]. / Losjetrykk etter margnagling av leggbrudd.

Acute compartment syndrome is a serious complication to tibial fractures. The reported incidence is 1-10%. The present series includes 60 patients treated with intramedullary nailing of fractures in the tibial diaphysis. Tissue pressure was measured in 31 patients. Decompressive fasciotomy was performed if the pressure exceeded 30 mm Hg for more than 30 minutes. Follow-up showed no patients with clinical sequelae from a compartment syndrome, but the incidence of fasciotomy was as high as 18%.

Fascia lata plasty in recurrent posterior dislocation after total hip arthroplasty.

With a soft-tissue plasty, stability could be obtained in 17 of 22 patients with unstable hips after total hip arthroplasty. While in 16 of 18 patients with a posterior instability stability was achieved, only 1 of 3 patients with a unstable hip for dislocation in all directions was successfully treated. No stability could be achieved in one patient with a hip which dislocated anteriorly. The method described should only be used for posterior recurrent dislocations after total hip arthroplasty.

Pairwise strength relationships of cortical and cancellous bone in human femur: an autopsy study.

To analyze the mechanical properties of cortical and cancellous bone in the femur and relate them to bone mineral, we retrieved 14 pairs of femurs from elderly subjects at autopsy. Bone mineral was measured by quantitative single-energy computed tomography. Significant associations were found between two types of cortical bone mechanical tests, three-point bending and pull-out of screw, one performed on the right and the other on the left femur. Similarly, pairwise associations were found between the mechanical tests of cancellous bone, punch and cube compression, one performed on the right and the other on the left femur. Also, all mechanical tests correlated with bone mineral as determined by quantitative single-energy computed tomography. In general, bone mass measures correlated better with bone strength than did bone density measures. However, the cortical and cancellous bone mechanical properties were not interrelated, which suggests a separate regulation of the strength of these two types of bone. Bone mineral may not only have importance for the occurrence of fractures; it should be considered as an important factor in the fixation of fragile bone.