CT analysis of femoral malrotation after intramedullary nailing of trochanteric fractures.

PURPOSE: Functional results after internal fixation of trochanteric femoral fractures may be negatively affected by healing in a non-physiological position. The aim of this study was to evaluate the occurrence and severity of femoral malrotation after nailing of trochanteric fractures. MATERIALS AND METHODS: The authors conducted a prospective study focused on a CT analysis of malrotation after intramedullary nailing of trochanteric fractures (AO 31A1-3) in 101 patients. We recorded the type of fracture, method of anesthesia, scheduled surgery vs. acute surgery, and the surgeon's experience as possible risk factors for limb malrotation after trochanteric fracture surgeries. RESULTS: The average extent of malrotation was 9° of internal rotation ranging from 29° of external to 48°of internal rotation. In 35% of patients, we observed a rotation greater than 15°, and in 15 patients (15%), the rotation was greater than 25°. The risk of significant internal malrotation was significantly higher than external malrotation (37 vs. 4 patients). None of the factors observed proved to be statistically significant. The effect of general anesthesia and the type of intertrochanteric fracture came closest to having a significant effect on rotational error. CONCLUSION: Improper reduction of a trochanteric fracture is a common problem that can lead to femur malrotation. In our study, a rotational error greater than 15° occurred in 35% of the patients, but none of the monitored factors represented a statistically significant risk for this complication.

The role of vascularization on changes in ligamentum flavum mechanical properties and development of hypertrophy in patients with lumbar spinal stenosis.

BACKGROUND CONTEXT: Ligamentum flavum (LF) induced lumbar spinal stenosis (LSS) is conditioned not only by its "gathering" but especially by hypertrophy. Previous studies have examined the pathophysiology and biochemical changes that cause the hypertrophy. Some studies have described a link between chronic LF inflammation and neovascularization but others have reported highly hypovascular LF tissue in LSS patients. Currently, there is no practical application for our knowledge of the pathophysiology of the LF hypertrophy. Considerations for future treatment include influencing this hypertrophy at the level of tissue mediators, which may slow the development of LSS. To our knowledge, there is no study of micromechanical properties of native LF to date. PURPOSE: (1) To clarify the changes in vascularization, chondroid metaplasia, and the presence of inflammatory cell infiltration in LF associated with LSS. (2) To quantify changes in the micromechanical properties associated with LF degenerative processes. STUDY DESIGN/SETTING: Vascular density analysis of degenerated and healthy human LF combined with measurement of micromechanical properties. METHODS: The study involved 35 patients who underwent surgery between November 1, 2015 and October 1, 2016. The LSS group consisted of 20 patients and the control group consisted of 15 patients. LF samples were obtained during the operation and were used for histopathological and nanoindentation examinations. Sample vascularization was examined as microvascular density (Lv), which was morphometrically evaluated using semiautomatic detection in conjunction with NIS-Elements AR image analysis software. Samples were also histologically examined for the presence of chondroid metaplasia and inflammation. Mechanical properties of native LF samples were analyzed using the Hysitron TI 950 TriboIndenter nanomechanical testing system. RESULTS: Vascular density was significantly lower in the LSS group. However, after excluding the effect of age, the difference was not significant. There was high association between Lv and age. With each increasing year of age, Lv decreased by 11.5 mm2. Vascular density decreased up to the age of 50. Over the age of 50, changes were no longer significant and Lv appeared to stabilize. No correlation was observed between Lv and the presence of inflammation or metaplasia; however, LSS patients had a significantly increased incidence of chondroid metaplasia and inflammatory signs. The mechanical properties of control group samples showed significantly higher stiffness than those samples obtained from the LSS group. CONCLUSION: This study showed that Lv changes were not dependent on LSS but were age-dependent. Vascular density was found to decrease up to the age of 50. A significantly higher incidence of chondroid metaplasia and inflammation was observed in LSS patients. The mechanical property values measured by nanoindentation showed high microstructural heterogeneity of the tested ligaments. Our results showed that healthy ligaments were significantly stiffer than LSS ligaments. CLINICAL SIGNIFICANCE: Prevention of the loss of LF vascularization during aging may influence stiffness of LF which in turn may slow down the LF degenerative processes and delay onset of LSS.

Cement augmentation of odontoid peg fractures: the effect of cement volume and distribution on construct stiffness.

PURPOSE: The cement augmentation of a conventional anterior screw fixation in type II odontoid process fractures for elderly patients significantly increased stiffness and load to failure under anterior-posterior load in comparison with non-augmented fixation. The amount and quality of bone cement are usually taken ad hoc in clinical practise. In this study, we wanted to clarify the role of bone cement amount and its quality to the stiffness of odontoid and vertebrae body junction. METHODS: Finite-element method was used to achieve different scenarios of cement augmentation. For all models, an initial stiffness was calculated. Model (1) the intact vertebrae were virtually potted into a polymethylmethacrylate base via the posterior vertebral arches. A V-shaped punch was used for loading the odontoid in an anterior-posterior direction. (2) The odontoid fracture type IIa (Anderson-D'Alonzo classification) was achieved by virtual transverse osteotomy. Anterior screw fixation was virtually performed by putting self-drilling titanium alloy 3.5 mm diameter anterior cannulated lag screw with a 12 mm thread into the inspected vertebrae. A V-shaped punch was used for loading the odontoid in an anterior-posterior direction. The vertebrae body was assumed to be non-cemented and cemented with different volume. RESULTS: The mean cement volume was lowest for body base filling with 0.47 ± 0.03 ml. The standard body filling corresponds to 0.95 ± 0.15 ml. The largest volume corresponds to 1.62 ± 0.12 ml in the presence of cement leakage. The initial stiffness of the intact C2 vertebrae was taken as the reference value. The mean initial stiffness for non-porous cement (E = 3000 MPa) increased linearly (R2 = 0.98). The lowest stiffness (123.3 ± 5.8 N/mm) was measured in the intact C2 vertebrae. However, the highest stiffness (165.2 ± 5.2 N/mm) was measured when cement leakage out of the odontoid peg occurred. The mean initial stiffness of the base-only cemented group was 147.2 ± 8.4 N/mm compared with 157.9 ± 6.6 N/mm for the base and body cemented group. This difference was statistically significant (p < 0.0061). The mean initial stiffness for porous cement (E = 500 MPa) remains constant. Therefore, there is no difference between cemented and non-cemented junction. This difference was not statistically significant (p < 0.18). CONCLUSION: The present study showed that the low porous cement was able to significantly influence the stiffness of the augmented odontoid screw fixation in vitro, although further in vivo clinical studies should be undertaken. Our results suggest that only a small amount of non-porous cement is needed to restore stiffness at least to its pre-fracture level and this can be achieved with the injection of 0.7-1.2 ml of cement. These slides can be retrieved under Electronic Supplementary Material.

Biomechanical comparison of cemented versus non-cemented anterior screw fixation in type II odontoid fractures in the elderly: a cadaveric study.

BACKGROUND CONTEXT: Odontoid process fractures are the most common injuries of the cervical spine in the elderly. Anterior screw stabilization of type II odontoid process fractures improves survival and function in these patients but may be complicated by failure of fixation. PURPOSE: The present study aimed to determine whether cement augmentation of a standard anterior screw provides biomechanically superior fixation of type II odontoid fractures in comparison with a non-cemented standard screw. STUDY DESIGN: Twenty human cadaveric C2 vertebrae from elderly donors (mean age 83 years) were obtained. METHODS: Anderson and D'Alonzo type IIa odontoid fracture was created by transverse osteotomy, and fluoroscopy-guided anterior screw fixation was performed. The specimens were divided into two matched groups. The cemented group (n=10) had radiopaque high viscosity polymethylmethacrylate cement injected via Jamshidi needle into the base of the odontoid process. The other group was not augmented. A V-shaped punch was used for loading the odontoid in an anteroposterior direction until failure. The failure state was defined as screw cutout or 5% force decrease. Mean failure load and bending stiffness were calculated. RESULTS: The mean failure load for the cemented group was 352±12 N compared with 168±23 N for the non-cemented group (p<.001). The mean initial stiffness of the non-cemented group was 153±19 N/mm compared with 195±29 N/mm for the cemented group (p<.001) CONCLUSIONS: Cement augmentation of an anterior standard screw fixation of type II odontoid process fractures in elderly patients significantly increased load to failure under anteroposterior load in comparison with non-augmented fixation. This may be a valuable technique to reduce failure of fixation.

Distal tibiofibular synostosis after surgically resolved ankle fractures: An epidemiological, clinical and morphological evaluation of a patient sample.

INTRODUCTION: Ankle fractures comprise a highly morphologically and etiologically diverse group of injuries, which includes various degrees of impairment of bone and ligamentous structures. The complete synostosis and incomplete bony bridging of tibiofibular syndesmosis are among the local late complications after surgically treated ankle fractures. PATIENTS AND METHOD: 269 patients were evaluated, including 203 patients with Weber type-B fractures, and 66 patients with Weber type-C fractures. All patients underwent ankle radiography at standard intervals (post-operatively, 6 and 12 weeks, 6 and 12 months). The final assessment one year after osteosynthesis was performed. The study analyzed age, sex, fracture morphology, the location and morphology of ossification, functional outcomes and subjective evaluations of patient status. RESULTS: As risk factors there were found male sex, tibiotalar dislocation, syndesmotic screw fixation and Weber type-C fractures. The severity of subjective difficulties and objective status were not dependent on the size of distal tibiofibular synostosis. DISCUSSION AND CONCLUSION: Despite relatively extensive imaging findings of complete synostosis or incomplete bony bridging, they only limited functional outcomes to a minimal extent.

Distal locking in short hip nails: Cause or prevention of peri-implant fractures?

OBJECTIVES: The most common cause of femoral fractures after osteosynthesis of trochanteric fractures with short nails is weakening of the femoral cortex via distal locking and stress concentrations at the tip of the nail. The aim of the study was to verify whether the incidence of peri-implant fractures is dependent upon the distal locking technique. METHODS: We prospectively analysed a group of 849 pertrochanteric fractures (AO/ASIF 31-A1+2) managed with short nails from 2009 to 2013. Unlocked nailing was performed in 70.1% and distal dynamic locking was performed in 29.9%. The mean age was 82.0 years. Peri-implant fractures were divided into 3 groups according to the height of the fracture in relation to the tip of the nail. RESULTS: In total 17 fractures (2.0%) were detected. One peri-implant fracture occurred after locked nailing, whereas 16 cases occurred after unlocked nailing (p=0.037). Patients without distal locking had an 85.7% greater risk of peri-implant fracture. Fractures of the proximal femur (Type I) occurred significantly earlier than fractures at the tip of the nail (Type II) (p=0.028). CONCLUSION: Unlocked nails do not guarantee sufficient stability. Distal locking serves to prevent postoperative femoral fractures. We recommend the routine use of distal locking when utilizing short nails.

The importance of intramedullary hip nail positioning during implantation for stable pertrochanteric fractures: biomechanical analysis.

PURPOSE: Proximal femoral fractures are among the most commonly sustained fractures. The current treatment of stable proximal femoral fractures located in trochanteric region primarily involves the use of two systems: extramedullary dynamic hip screws and intramedullary hip nails. Given that these fractures are mainly found in the elderly population, the necessity of a repeat, due to failure of the first, may jeopardize the patient's life. Decisive factors contributing to the healing of a fracture (or the failure thereof) include fracture pattern, technical implementation of the operation (i.e., position of the implant), implant's properties and its changes in relation to the surrounding bone tissue during loading. Each screw insertion variant results in damage to various load-bearing bone structures, which can be expected to influence healing quality and stability of newly formed bone. METHOD: With the aid of a numerical model and finite element methods, the authors analyzed several different positions of IMHN/PFH-nails in the proximal femur, with the objective of determining positions with an increased risk of failure. RESULTS AND CONCLUSION: In model situations, it has been shown that in stable fractures results do not depend on absolutely precise positioning and small deflections in the nails and neck screws positions do not significantly increase the risk of failure for the entire fixation. Damage to load-bearing structures relative to various implant placements does not impact the resultant overall fixation stability. Therefore, it is not necessary to re-introduce implants in the ideal position, which can lead to reduced patient radiation doses during surgery.

Subsequent contralateral hip fractures: can at-risk patients be identified? An observational study of 5,102 patients.

PURPOSE: The aim of this study was to evaluate a sample of patients who sustained hip fractures during the years 1997-2011 and identify risk factors for a subsequent contralateral hip fracture; one-year mortality rates were compared in both groups. METHODS: A total of 5,102 patients with hip fractures were prospectively studied to identify patients who had also suffered a subsequent, contralateral, hip fracture (SCHF). Those patients who had sustained a second fracture within 18 months of the initial fracture were then studied. All data were statistically processed. RESULTS: Within 18 months of the first fracture, a SCHF occurred in 105 patients (2.1 %). These patients were an average of three years older than those in the single fracture group. Risk factors for the development of a SCHF included: female gender, residing in a residential care facility, and limited mobility prior to injury. Trochanteric fractures did not represent a statistically significant risk factor for SCHF. More than three-quarters of patients with subsequent injuries suffered the same type of fractures on the opposite side. Patients with subsequent fractures had lower one-year mortality rates than patients with only one fracture. CONCLUSION: Patients at greatest risk for a SCHF were women with limited mobility who resided in nursing homes for the elderly. The lower mortality rate associated with second fractures shows that the prognosis for such patients is good. Since the at-risk group is so well defined, prophylactic measures for these patients should be utilized in order to minimize the risk of additional fractures.

Combined traumatic atlantooccipital and atlantoaxial articulation instability: a case report with survival.

Traumatic atlantooccipital dislocation is a rare injury in survivors with 15 % share in deaths due to spinal injury. The authors present a case of a patient with concurrent atlantooccipital and atlantoaxial instability of the upper cervical spine, which he suffered after a fall from height. Atlantooccipital dislocation in surviving patients is a rare injury, for which in some cases coincident bone injury is reported to upper cervical spine, such as occipital fracture or contingent odontoid (C2 dens) fracture. In our case, it is combined with atlantoaxial instability and this combined type of injury has not yet been described in the literature. We performed realignment of the dislocation and posterior occipitocervical (C0-C3) fusion. After the surgery, the patient manifested neurological improvement almost to a normal neurological outcome with persistent residual finding after subarachnoid hemorrhage.

Single-centre study of hip fractures in Prague, Czech Republic, 1997-2007.

This study examines the epidemiological data of patients with hip fractures from 1997-2007. Adult patients treated for hip fracture between the years 1997-2007 were included in the study. Retrospective statistical assessment of continually gathered data focussed on epidemiology and demographics. The study involved 3,683 patients (2,678 women and 1,005 men). Patients older than 70 years accounted for 82% of all cases. There were 2.7 times more women; in patients younger than 60 years men significantly outnumbered women (p < 0.001). The mean patient age was 77.9 years (SD ± 12.6; women, 80.3 years; men, 71.5 years). There was a slight increase in the average age in both sexes. Trochanteric fractures accounted for 54.7% and femoral neck fractures accounted for 45.3% of fractures. The ratio of men to women was the same in femoral neck (AO-31B) and trochanteric (AO-31A) fractures. The average year-to-year increase in the number of fractures was 5.9%. For femoral neck fractures (AO-31B), there was a statistically insignificant increase in the number of fractures (p = 0.63); for intertrochanteric factures (AO-31A3) there was a statistically insignificant decrease (p = 0.65). There was an increase in the number of hip fractures resulting in a significant increase in pertrochanteric fractures (AO-31A1+2) (p < 0.001). The ratio of trochanteric to neck fractures increased from 0.99 to 1.53. Continual monitoring of patients with hip fracture offers data which allows comparisons between regions and countries. There has been a continual increase in the number of patients with hip fractures.

Is distal locking with IMHN necessary in every pertrochanteric fracture?

Two groups of patients were treated for pertrochanteric fractures (AO/ASIF 31A1+A2) with an intramedullary hip nail. In the first group of 44 patients distal dynamic locking was used, and in the second group of 74 patients the nail was not distally locked. Comparison of the two groups of patients did not show any difference in terms of the period of fracture healing, radiological and functional results or frequency of complications. In the group with a distally locked nail the surgery took 40.4 minutes, while in the group without distal locking only 34.4 minutes. In total, we recorded only seven complications, none of which were caused by absence of distal locking of the nail. This study has shown that distal locking of IMHN is unnecessary in most pertrochanteric fractures (AO/ASIF 31A1+2). The only exceptions are comminution of the lateral wall of the greater trochanter, secondary diaphyseal fracture line, large posteromedial fragment extended distally below the level of the lesser trochanter and broad intramedullary canal.

Avascular necrosis of the femoral head in pertrochanteric fractures: a report of 8 cases and a review of the literature.

OBJECTIVE: To evaluate patients with pertrochanteric fractures (Type 31A1 + 2 ASIF/OTA classification) treated surgically and who subsequently developed avascular necrosis of the femoral head (ANFH). SETTING: University hospital. DESIGN: Retrospective clinical study and analysis of the literature. PATIENTS: From 1995 to 2003 the authors operated on 1,373 patients with pertrochanteric fractures. Eight patients with a mean age of 69 years (range, 52-78 years) subsequently developed ANFH. INTERVENTION: Five patients were treated with a dynamic hip screw (DHS), and 3 were treated with an intramedullary hip nail (IMHN). RESULTS: All fractures in these 8 patients healed without complications in 3 to 4 months. Avascular necrosis of the femoral head developed 4 months to 4 years after the operation. Detailed analysis of these cases did not reveal any risk factors or errors in surgical technique to account for the ANFH. Results of a literature review of 41 cases in addition to our 8 cases give us reason to believe the etiology of postoperative AFNH following surgical treatment of pertrochanteric fractures is probable injury to the deep branch of the medial circumflex artery at time of fracture. Other possible risk factors include high-energy trauma, comminution, displacement of the fragments, and atypical fracture line. CONCLUSIONS: ANFH develops in approximately 0.5-1% of all pertrochanteric fractures, mostly within 4 years after the injury and predominantly in patients older than 50 years of age. The diagnosis should be considered in patients who have undergone an operation previously and have symptoms that are unclear. Prevention of ANFH in these fractures includes an early reduction, stable fixation, and correct surgical technique.

Valgus intertrochanteric osteotomy for malunion and nonunion of trochanteric fractures.

OBJECTIVE: To evaluate the results of valgus intertrochanteric osteotomy for varus nonunion and malunion of trochanteric fractures. SETTING: University hospital. DESIGN: Retrospective clinical study. PATIENTS: Fifteen patients (age range 29-84 years) with varus malunion (11 cases) or varus nonunion (4 cases). Indication for surgery was nonunion or varus malunion with limb shortening greater than 2 cm associated with limp, abductor muscle insufficiency, hip pain, and back pain. INTERVENTION: The patients were treated by a valgus intertrochanteric osteotomy fixed with a 120 degrees double-angled blade plate. RESULTS: Average follow-up was 5.5 years (range 2-10 years). Fourteen patients healed without complications: 12 patients within 4 months; 2 delayed unions within 6 months. One patient required revision surgery for a loss of fixation due to a fall 6 weeks after surgery. This osteotomy also healed. Average lengthening achieved by osteotomy was 2 cm (range 1-5 cm). In all patients, the resulting range of flexion in the hip joint was greater than 90 degrees, Harris hip score before surgery was 73 points (range 61-83), and after surgery 92 points (range 76-98). Osteoarthritis or avascular necrosis of the femoral head did not develop in any of the cases. CONCLUSION: Valgus intertrochanteric osteotomy is an effective procedure that reliably restores hip function in trochanteric malunion or nonunion.