Does hip implant positioning affect the peak external adduction moments of the healthy knees of subjects with total hip replacements?

After unilateral total hip replacement (THR) for hip osteoarthritis (OA), knee OA incidence or progression is common. The contralateral knee is at particular risk, and some have speculated that abnormal THR‐hip biomechanics contributes to this asymmetry. We investigated the relationships between operated‐hip joint geometry or gait variables and the peak external knee adduction moments—an indicator of knee OA risk—in 21 subjects with unilateral THRs. We found that the peak adduction moment was 14% higher on the contralateral versus the ipsilateral knee (p = 0.131). The best predictors of ipsilateral knee adduction moments were superior‐inferior joint center position and operated‐hip peak adduction moment (adj R² = 0.291, p = 0.017). The sole predictor of the contralateral knee adduction moment was the medial‐lateral hip center position (adj R² = 0.266, p = 0.010). A postoperative medial shift of the hip center was significantly correlated with a lower postoperative contralateral/ipsilateral knee adduction moment ratio (R = 0.462, p = 0.035). Based on these relationships, we concluded that implant positioning could influence the biomechanical risk of knee OA progression after THR. Although implant positioning decisions are necessarily driven by other factors, it may be appropriate to assess individual THR candidate's knee OA risk and adjust perioperative management accordingly. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1187–1194, 2013     

Antegrade nailing of femoral shaft fractures combined with neck or distal femur fractures

Introduction Complex femoral fractures pose considerable therapeutic challenges to orthopedic surgeons. We present a retrospective review of 25 patients with complex femoral fractures treated with intramedullary locked nailing and supplemental screw fixation.Materials and methods Fifteen patients with ipsilateral femoral neck and shaft fractures (group 1) and 10 patients with ipsilateral femoral shaft and distal femur fractures (group 2) were treated from 1990 to 1998. High-energy injuries occurred in all patients. There were 4 open fractures. Antegrade, locked nailing of diaphyseal fractures was performed in all cases. Supplemental screws for the neck were used in all patients in group 1 and in 3 patients in group 2.Results All of the fractures united during the follow-up. Five patients in group 1 underwent reoperation (33.3%): one due to a delayed union, the second due to an implant failure, the third due to a nonunion of a neck fracture, and the last two because of an initially missed femoral neck fracture. None of the patients in group 2 underwent reoperation. Angular malalignment of the shaft was found in 6 fractures in group 1 (average 4.8^o, range 3^o–11^o) and in 4 fractures in group 2 (average 6^o, range 3^o–12^o). Shortening of the limb occurred in 3 patients in group 1 (average 1.4 cm, range 1–1.8) and in 1 patient in group 2 (2 cm). Loss of fixation was seen in 1 patient in each group. Avascular necrosis and infection were not seen in any case in both groups.Conclusion Femoral intramedullary nails with antegrade or retrograde options for insertion and different locking possibilities have extended the indications to include both diaphyseal and metaphyseal fractures. New nail designs, usually more expensive than the conventional nails, have been introduced into the market for this purpose. One has to keep in mind that antegrade, locked nailing of femoral shaft fractures combined with neck or distal femur fractures is a technically demanding but efficacious procedure. The success rate is high when the technique is meticulously implemented.     

Ipsilateral femoral neck and shaft fractures. Report of two cases using an alternate technique

A technique for ipsilateral femoral neck and shaft fracture using the sliding compression hip screw with plate combined with trochanteric antegrade Ender nailing of the femur was applied in two cases. Ender nails can be passed without difficulty past a compression hip screw and the bicortical plating screws. The hip and femur can be fixed internally through a single approach in a single position. Sliding compression hip screw devices can provide excellent preliminary stable femoral neck fixation. Blood supply to the femoral head is not disturbed while the femoral intramedullary fixation is performed. Antegrade Ender nailing avoids the common knee complications associated with other retrograde techniques. Decreased operative time, less blood loss, less technical difficulty, and early mobilization are important factors in the multiple-injured patient. Femoral intramedullary fixation may require open reduction, circlerage to ensure stability, and maintenance of alignment in case of significant comminution to allow early crutch ambulation. This mode of fixation may be advantageous for selected cases.     

A comparison of intramedullary nailing and plate-screw fixation in the treatment for ipsilateral fracture of the hip and femoral shaft

We compared the outcomes of intramedullary nailing with plate-screw fixation in the treatment for ipsilateral fracture of the hip and femoral shaft. A retrospective study. Level 1 Trauma. Forty-one patients (32 males and 9 females; mean age, 34 years; age range, 21–53) with ipsilateral hip and femoral shaft fractures were treated between 1995 and 2005. Eighteen patients were injured in motor vehicle accidents, and 23 fell from a height. All patients were treated by one of the two methods of internal fixation: a screw-plate fixation (n = 24, Group I) or intramedullary nailing (n = 17, Group II). The fracture union time, nonunion, delayed union, implant failure, need of further surgeries, and functional outcomes were investigated and compared. Fisher’s exact test showed that Group I had a significantly higher frequency of nonunion than that of Group II (P = 0.029). Although Group I had more nonunions, delayed unions, and revision operations than Group II, the total union time was similar for both groups. Intramedullary nailing was found to be superior to screw-plate fixation due to improved functional bearing, increased rate of union, stability, and mechanical solidity. The reconstruction nail method is an acceptable alternative treatment for ipsilateral hip and femoral shaft fractures.     

Marknagelung des Femurs mit einem helikalen Implantat (LFN®)

Objective

Antegrade femoral nailing through a greater trochanteric entry portal avoids damage to the proximal external rotators and to the ramus profundus of the medial femoral circumflex artery, furthermore eases insertion in adipose subjects. However a helical nail shape is necessary for this pathway because bending in two perpendicular planes has to be passed by the nail.

Indications

All femoral shaft fractures suitable for antegrade nailing (type 32-A/B/C). Additional femoral neck fractures (type 31-B) by using proximal Recon-interlocking screws.

Contraindications

The common contraindications for femoral nailing. In certain subtrochanteric fractures (Type 32-A/B) the proximal femoral nail may be favorable.

Surgical technique

General or spinal anesthesia. Supine position with flexion/abduction of the contralateral leg in order to facilitate fluoroscopy of the proximal femur in a true lateral view. Closed reduction of length and axis. Measurement of length and diameter of the nail using a radiolucent ruler. Dorsolateral approach to the greater trochanter. Insertion of the guide wire 10 mm lateral to the trochanteric tip (anteroposterior view) and in the middle third of the trochanter (lateral view). Reaming of the insertion point using a flexible reamer. If reaming of the entire medullary canal is desired, this should be done using a long intramedullary guide wire in combination with a long flexible reamer. Insertion of the nail starts in an anterior position and ends in a lateral position of the insertion instrument, so a 90° external rotation of the nail occurs during insertion. Proximal interlocking is performed using the guide of the insertion instrument. Check interfragmentary rotation. Distal interlocking using a radiolucent drill device.

Postoperative management

Depends on the fracture shape: stable interfragmentary support may allow early full weight bearing. Otherwise, reduced weight bearing is recommended for at least 6 weeks.

Results

In a prospective mulicentric study, 227 helical femoral nails were used for antegrade femoral nailing. Follow-up after 12 month was available in 74?%. Surgeons’ rating for ease of identifying entry site was excellent or good in 89?%. Functional and radiological results after 12 months do not prove significant benefits over conventional antegrade femoral nails.     

Hip fractures following intramedullary nailing fixation for femoral fractures

IntroductionProximal peri-implant femoral fractures occur following intramedullary nailing (IMN) fixation for trochanteric, femoral shaft, and distal femoral fractures. However, analyses of secondary hip fractures (SHFs) using large clinical samples are lacking. Therefore, we aimed to report the incidence and clinical outcomes of SHF after nailing fixation (IMN or cephalomedullary nailing [CMN]) for overall femoral fractures. In addition, we focused on IMN for femoral shaft fractures and investigated the risk factors for SHF.MethodsThis multicenter, retrospective, cohort study included 2,293 patients aged > 60 years who underwent nailing fixation for femoral fractures. The primary outcome was the incidence of SHF. In the assessment of clinical outcomes, we evaluated reoperation and the regaining of walking ability following SHF management. In addition, we conducted multivariable logistic regression analyses to examine the association between risk factors and SHF.ResultsSeventeen (0.7%) patients had SHFs, including 12 femoral neck fractures and 5 trochanteric fractures. Antegrade IMN was the most common type of nailing fixation. Multivariable analysis demonstrated that the absence of femoral head fixation was significantly associated with the incidence of SHF following IMN for femoral shaft fractures (odds ratio, 17.0; 95% confidence interval, 1.9–2265.7; p=0.006). In the assessment of clinical outcomes, there were two reoperations (16.7%) in the secondary femoral neck fracture group. Patients with secondary trochanteric fractures tended to have a lower probability of regaining walking ability than those with secondary femoral neck fractures (20% vs. 50%).ConclusionsIn this multicenter study, the incidence of SHF after nail fixation for femoral fractures was 0.7%. The absence of femoral head fixation was significantly associated with SHF, and the clinical outcomes were poor. Therefore, femoral head fixation at the initial IMN fixation for femoral fractures may be a fixation option for surgeons to consider as an SHF prevention measure.     

Femoral neck cortical geometry measured with magnetic resonance imaging is associated with proximal femur strength

Introduction Magnetic resonance imaging (MRI) is a promising medical imaging technique that we used to assess femoral neck cortical geometry.Objectives Our primary objective was to assess whether cortical bone in the femoral neck assessed by MRI was associated with failure load in a simulated sideways fall, with and without adjustment for total bone size. Our secondary objective was to assess the reliability of the MRI measurements.Materials and methods We imaged 34 human cadaveric proximal femora using MRI and dual-energy X-ray absorptiometry (DXA). MRI measurements of cross-sectional geometry at the femoral neck were the cortical cross-sectional area (CoCSA_MRI), second area moment of inertia (x axis; Ix_MRI), and section modulus (x axis; Zx_MRI). DXA images were analyzed with the standard Hologic protocol. From DXA, we report the areal bone mineral density (aBMD_DXA) in the femoral neck and trochanteric subregions of interest. The femora were loaded to failure at 100 mm/s in a sideways fall configuration (15° internal rotation, 10° adduction).Results and observations Failure load (N) was the primary outcome. We observed that the femoral neck CoCSA_MRI and Ix_MRI were strongly associated with failure load (r ²=0.46 and 0.48, respectively). These associations were similar to those between femoral neck aBMD and failure load (r ²=0.40), but lower than the associations between trochanteric aBMD and failure load (r ²=0.70).Conclusion We report that MRI holds considerable promise for measuring cortical bone geometry in the femoral neck and for predicting strength at the proximal femur.     

Erfahrungen mit einem helikalen Femurmarknagel (LFN®)

Introduction

Antegrade intramedullary nailing is the method of choice in most femoral shaft fractures. The trochanteric entry portal of classic femoral nails is in close proximity to the piriformis tendon, the gluteus minimus tendon, the obturator tendons, and the medial femoral circumflex artery. Nail insertion lateral to the tip of the greater trochanter may be more favorable but needs the use of a helical implant.

Material and methods

Measurement of the reamer pathway through an entry point lateral to the superior trochanteric border was performed with a three-dimensional motion tracking sensor in human cadaveric femurs. These results provided a scientific rationale for the design of a helical femoral nail (LFN®). In a prospective multicenter study a total of 227 femoral shaft fractures were treated by nailing with the LFN. Patients were followed at 3 months (n=193) and 12 months (n=167).

Results

The ease of defining the entry point and inserting the nail was rated as“very good and good” by 90% of the surgeons. Intraoperative technical complications included incomplete reduction (14%), additional iatrogenic fractures (6%), and difficulties in interlocking (3.5%). At the 1-year follow-up, delayed unions were seen in 10%, secondary loss of reduction in 3%, and deep infection in 1.8% of the patients. Angular malalignment of more than 5° was seen in 5%, mostly in valgus. A normal walking capacity was seen in 68% and normal active hip flexion in 45%.

Conclusion

The results obtained in this study during 1 year do not provide evidence for an advantage of the LFN over conventional antegrade femoral nails.     

Stable Trochanteric Fractures. A Comparative Analysis of four Methods of Internal Fixation

A series of 375 patients with stable trochanteric fractures were treated with the McLaughlin or Jewett nail-plate, the sliding screw-plate or Ender nailing.

Technical failure of fixation was encountered in 5 per cent of the cases regardless of the method of fixation used. Re-operations were performed in less than 3 per cent of cases treated with hip implants but in 20 per cent of cases with Ender nailing, mainly because of distal slipping of the nails resulting in knee problems.

With an improved technique, however, Ender nailing can be used as successfully as any of the hip implants for the internal fixation of stable trochanteric fractures.     

Risk of superior gluteal nerve and gluteus medius muscle injury during femoral nail insertion

BACKGROUND: Abduction weakness and limping is a well-recognized complication of closed antegrade insertion of femoral nails. Iatrogenic injuries to the superior gluteal nerve and the gluteus medius muscle are the most likely contributing factors. The purpose of this study of cadavers was to assess the risk of nerve and muscle injury with various lower-limb positions used during nail insertion. METHODS: We studied thirteen hips of ten formalin-fixed adult cadavers. With the cadaver in the full lateral position, a 9-mm reamer was introduced in a retrograde fashion from the intercondylar notch and passed through the gluteus medius muscle. The distance between the point of entry of the reamer into the undersurface of this muscle and the inferior main branch of the superior gluteal nerve (the nerve-reamer distance) and the distance between the entry and exit points of the reamer in the gluteus medius muscle (the intramuscle distance) were measured in three different hip positions: 15 degrees of flexion and 15 degrees of adduction (Position 1), 30 degrees of flexion and 30 degrees of adduction (Position 2), and 60 degrees of flexion and 30 degrees of adduction (Position 3). RESULTS: In Position 1, the average nerve-reamer distance was 7 mm and the average intramuscle distance was 24 mm. In three hips the reamer injured the nerve directly, and in two other hips the distance was 相似文献   

Structural determinants of hip fracture in elderly women: re-analysis of the data from the EPIDOS study

Hip fracture is the most disastrous osteoporotic fracture, characterized by high mortality, morbidity and institutionalization for the patient and by high economic costs for the health care system. The morphology of the upper part of the femur can influence the risk of hip fracture, e.g., a longer femoral neck is associated with a higher risk of cervical fractures, but not trochanteric ones. In this study, we evaluated the prediction of hip fracture risk by morphological parameters estimated from DXA measurements, and we compared their predictive value for cervical and trochanteric fractures in elderly women by reanalyzing previously published data (Duboeuf et al. J Bone Miner Res 1997 12 1895). This nested case-control study was performed in 232 elderly community-dwelling women from the EPIDOS cohort, including 65 women who sustained a hip fracture. After adjustment for confounding variables, women who sustained a cervical fracture had lower areal bone mineral density (aBMD), lower cortical thickness and a higher average buckling ratio ( P <0.005 for all) as well as longer femoral neck ( P <0.01) than controls. Women who sustained a trochanteric fracture had lower aBMD, lower cortical thickness and higher buckling ratio than controls ( P <0.0001) and than women who sustained a cervical fracture ( P <0.05). Their bending resistance (cross-sectional moment of inertia—CSMI, section modulus) was significantly lower in comparison with controls ( P <0.05–0.001). A decrease in aBMD, cortical thickness, CSMI and section modulus as well as an increase in buckling ratio were predictive of all hip fractures (OR –1.42–2.46 per 1 SD, P <0.05–0.0001), but the ORs for all structural parameters were markedly higher for trochanteric than for cervical fractures. CSMI and section modulus were predictive of trochanteric, but not cervical fractures. However, aBMD was strongly correlated with the CSA, cortical thickness and buckling ratio ( r ²>0.74), which suggests that they convey the same information. CSMI and section modulus correlated with aBMD more weakly, but their OR lost statistical significance after adjustment for aBMD. In conclusion, low femoral neck aBMD, CSA and cortical thickness as well as a high buckling ratio are associated with the higher risk of hip fracture, especially trochanteric ones. These indices are highly correlated with aBMD and convey the same message. The calculated CSMI and section modulus predict trochanteric fractures, but not cervical fractures, and their statistical significance is lost after adjustment for aBMD, indicating that they reflect mainly aBMD, not mechanical properties. Thus, the independent contribution of the external diameter of the femoral neck to the risk of hip fracture cannot be reliably estimated by this technique.     

A five-year review comparing 30-day mortality following intramedullary nailing versus sliding hip screw for trochanteric hip fractures

IntroductionRecent literature suggests that fixation of trochanteric hip fractures with intramedullary nailing carries a higher 30-day mortality than with sliding hip screw. The present study aims to verify whether this statement is reflected in our practice.Patients and MethodsSliding hip screw and intramedullary nail fixation of trochanteric hip fractures were analysed over a 5-year period, between April 2011 and March 2016. Three investigators independently analysed 919 patients. Data collected included 30-day mortality, OTA classification of hip fracture and ASA grading. Inclusion and exclusion criteria were applied.Results493 patients (66%) underwent sliding hip screw while 252 patients (34%) underwent intramedullary femoral nailing. AO/OTA classification was strongly associated with treatment group. It was found that 30-day mortality rate was 4.8% following intramedullary nailing compared to 6.1% with sliding hip screw. Multivariate logistic regression analysis found ASA grade, male gender and age to be associated with increased 30-day mortality with statistical significance. There was no statistically significant association between treatment group and 30-day mortality, nor between ASA grade and treatment group.ConclusionsBoth the lower 30-day mortality rate of 4.8% with intramedullary nailing and the higher rate of 6.1% with sliding hip screw fixation compare favourably with the mean 7.9% National 30-day mortality rate following hip fractures. The lower 30-day mortality in the intramedullary nailing group was not attributable to lower ASA grading nor due to simpler fracture configuration. ASA grade, male gender and age were shown to be statistically associated with increased 30-day mortality.ImplicationsPrevious studies may have deterred surgeons from choosing an intramedullary device. However, we hope this study assists surgeons to make an informed decision on the choice of implant particularly when an intramedullary device is required to provide a more stable construct.     

Retrograde nailing with subsequent screw fixation for ipsilateral femoral shaft and neck fractures

Introduction Although ipsilateral femoral shaft and neck fractures are difficult to treat, there is still no consensus on the optimal treatment of this complex injury. We report the results of treating the 17 fractures with a standard protocol of retrograde nailing for diaphyseal fractures and subsequent screw fixation for the femoral neck fractures. Materials and methods Seventeen injuries (16 patients) sustained femoral shaft fractures, which were treated with retrograde intramedullary nails and subsequent screw fixation. Femoral neck fracture was noted before the operation in all patients except one. A femoral shaft fracture was always addressed first with unreamed retrograde nailing. Then, the femoral neck fracture was treated by cannulated screws or dynamic hip screw according to the level of fracture. Results The average time for union of femoral shaft fractures was 27.3 (14–60) weeks. Nonunion occurred in five patients, who required bone grafts or changes of fixation. The average time for union of femoral neck fractures was 11 (8–12) weeks. All united, except for one case of nonunion with avascuar necrosis, which was a Garden stage IV fracture. Functional results using Friedman–Wyman criteria were good in 16 cases, and fair in one. The only fair result was nonunion of the femoral neck, which had the joint arthroplasty. Conclusion Retrograde nailing of femoral shaft fractures can provide an easy fixation and a favorable result for ipsilateral femoral neck fractures.This study was conducted at Kyungpook National University Hospital, Daegu, South Korea. The authors have and will not receive any financial benefit in association with the present paper.     

How to best measure femoral length and lateralisation after total hip arthroplasty on antero-posterior pelvic radiographs

Purpose

Various methods exist for measuring limb length and lateralisation after total hip arthroplasty. Most of them utilise standard anteroposterior (AP) pelvic radiographs, but their results can be affected by patient position during imaging and thus the position of the lower limb on the coronal plane. The aim of this study is to evaluate how commonly used measuring methods of limb lengthening and femoral offset are affected by the position of the lower limb in the coronal plane.

Methods

A standing pelvic AP radiograph post implantation of a right total hip prosthesis was digitised. The right femur and its femoral stem were digitally segmented, such that they could be positioned orthogonal to the pelvis horizontal reference, with 10° of adduction, and with 10° of abduction, with respect to the centre of rotation. Various limb lengths and implant lateralisation were also digitised. We obtained nine x-rays differing one to three variables. Twice four independent surgeons performed three femoral length measurement methods and femoral offset measurement methods. Intra and inter-observer error as well as the effect of the femoral position on the measurements were studied.

Results

With respect to length measurements, the distance between the centre of rotation (C) and the tip of the lesser trochanter (LT) increased by 3 mm per cm of lateralisation. This measurement was not affected by the hip position in abduction or adduction. The distance between the tip of the lesser or greater trochanter (GT) and the horizontal passing through the centre of rotation was strongly affected by the hip position in abduction or adduction. With respect to offset, the distance between the centre of rotation and the greater trochanter (C-GT) was the most consistent and was not affected by variations in lengths or femoral axis. At the level of the lesser trochanter, the distance of the femoral anatomical axis and to Perkin’s line was heavily influenced by the femoral position.

Conclusion

The C-LT distance was consistent in measuring limb length and the C-GT distance was reliable in determining femoral offset regardless of the relative position of the femur.

     

Retrograde Marknagelung bei periprothetischen Frakturen des distalen Femurs

Objective

Intramedullary stabilization of periprosthetic distal femoral fractures by interlocking nailing. Closed reduction by retrograde nail can be combined with the use of transmedullary support screws (TMS principle of Stedtfeld).

Indications

Supracondylar fractures above stable knee arthroplasty (Rorabeck types I and II), femoral shaft fractures ipsilateral of stable hip and/or knee arthroplasty, contraindications for antegrade nailing

Contraindications

Closed box design of femoral implant, intercondylar distance of the femoral component smaller than nail diameter, more than 40° flexion deficit of the knee, inability to place two bicortical distal interlocking screws. Relative contraindication: insufficient overlap with proximal implants

Surgical technique

Supine position and knee flexion of approximately 45°. Fluoroscopy should be possible between the knee and hip. Longitudinal skin incision into the pre-existing scar over the patellar tendon which is then split. The nail entry point is located in the intercondylar groove at the deepest point of Blumensaat’s line, often predetermined by the femoral arthroplasty component. Reaming is rarely necessary. Transmedullary support screws may correct axial malalignment during nail insertion. Static interlocking in a direction from lateral to medial by the aiming device. Insertion of locking cap.

Postoperative management

Retrograde nailing normally allows full weight bearing. Range of motion does not need to be restricted.

Results

Out of 101 fractures treated between 2000 and 2013 with a Targon RF nail (Aesculap, Tuttlingen, Germany) 10 were periprosthetic, all were classified as Rorabeck type II and of these 6 fractures were metaphyseal and 4 were diaphyseal. In four cases proximal implants were present. The mean operative time for periprosthetic fracture fixation did not significantly differ from that for normal retrograde femoral nailing. There were no postoperative infections, fixation failures or delayed unions. There was one revision for secondary correction of maltorsion.     

Combination of bone mineral density and upper femur geometry improves the prediction of hip fracture

Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is the main determinant of the clinical evaluation of hip fracture risk. However, it has been shown that BMD is not the only predictive factor for hip fracture, but that bone geometry is also important. We studied whether the combination of bone geometry and BMD could further improve the determination of hip fracture risk and fracture type. Seventy-four postmenopausal females (mean age 74 years) with a non-pathologic cervical or trochanteric hip fracture without previous hip fracture or hip surgery constituted the study group. Forty-nine had a cervical fracture (mean age 73 years) and 25 had a trochanteric fracture (mean age 76 years). The control group consisted of 40 age-matched females (mean age 74 years). The geometrical parameters were defined from plain anteroposterior radiographs, and the potential sources of inaccuracy were eliminated as far as possible by using a standardized patient position and calibrated dimension measurements with digital image analysis. BMD was measured at the femoral neck (FEBMD), Wards triangle (WABMD), and the trochanter (TRBMD). Stepwise linear regression analysis showed that the best predictor of hip fracture was the combination of medial calcar femoral cortex width (CFC), TRBMD, neck/shaft angle (NSA), and WABMD (r=0.72, r²=0.52, P<0.001). The area under the receiver operating characteristic curve (ROC) for this model was 0.93, while the area under ROC for TRBMD alone was 0.81. At a specificity of 80%, sensitivity improved from 52.5% to 92.5% with this combination compared with TRBMD alone. The combined predictors of cervical and trochanteric fracture differed, being NSA, CFC, TRBMD, and WABMD for cervical and TRBMD and femoral shaft cortical thickness for trochanteric fracture. In addition, we found a statistically significant correlation between FEBMD and femoral shaft and femoral neck cortex width (r=0.40, P<0.01 and r=0.30, P<0.01, respectively). The results confirm that the combination of BMD and radiological measures of upper femur geometry improve the assessment of the risk of hip fracture and fracture type compared to BMD alone, and that bone geometry plays an important role in the evaluation of bone strength.     

Evaluation of malrotation following intramedullary nailing in a femoral shaft fracture model: Can a 3D c-arm improve accuracy?

IntroductionDifficulty determining anatomic rotation following intramedullary (IM) nailing of the femur continues to be problematic for surgeons. Clinical exam and fluoroscopic imaging of the hip and knee have been used to estimate femoral version, but are inaccurate. We hypothesize that 3D c-arm imaging can be used to accurately measure femoral version following IM nailing of femur fractures to prevent rotational malreduction.MethodsA midshaft osteotomy was created in a femur Sawbone to simulate a transverse diaphyseal fracture. An intramedullary (IM) nail was inserted into the Sawbone femur without locking screws or cephalomedullary fixation. A goniometer was used to simulate four femoral version situations after IM nailing: 20° retroversion, 0° version, 15° anteversion, and 30° anteversion. In each simulated position, 3D c-arm imaging and, for comparison purposes, perfect lateral radiographs of the knee and hip were performed. The femoral version of each simulated 3D and fluoroscopic case was measured and the results were tabulated.ResultsThe measured version from the 3D c-arm images was 22.25° retroversion, 0.66° anteversion, 19.53° anteversion, and 25.15° anteversion for the simulated cases of 20° retroversion, 0° version, 15° anteversion, and 30° anteversion, respectively. The lateral fluoroscopic views were measured to be 9.66° retroversion, 12.12° anteversion, 20.91° anteversion, and 18.77° anteversion for the simulated cases, respectively.ConclusionThis study demonstrates the utility of a novel intraoperative method to evaluate femur rotational malreduction following IM nailing. The use of 3D c-arm imaging to measure femoral version offers accuracy and reproducibility.     

Die offene Therapie des femoroazetabulären Impingements

Objective

Elimination of an intraarticular femoroacetabular impingement conflict. Creation of a pain-free, normal range of motion of the hip.

Indications

Femoroacetabular impingement of any type (cam/pincer) and any localization (anterior/posterior).

Contraindications

Absolute: advanced hip osteoarthritis, local infections around the hip. Relative: excessive acetabular retroversion with deficiency of the posterior wall.

Surgical Technique

Lateral decubitus position. Straight lateral incision centered over the greater trochanter. Entering of the Gibson interval. Digastric trochanteric osteotomy with protection of the medial circumflex femoral artery. Opening of the interval between the piriformis and the gluteus minimus muscle. Z-shaped capsulotomy. Dislocation of the femoral head. Detachment of the labrum. Trimming of the excessive acetabular rim. Refixation of the labrum. Creation of a sufficient femoral head-neck offset. Suture of the capsule. Refixation of the trochanter.

Postoperative Management

During hospital stay, intensive mobilization of the hip joint using a continuous passive motion machine with a maximum flexion of 90°. No active abduction and passive adduction over the body’s midline. Maximum weight bearing 10–15 kg for 6 weeks. Subsequently, first clinical and radiographic follow-up. Deep venous thrombosis prophylaxis until full weight bearing.

Results

Short- and mid-term results showed an improvement of the postoperative clinical score (Merle d’Aubigné Score) in 95% of all patients, depending on the individual degenerative joint alterations at the time of surgery. Good to excellent results were obtained in 91% of all cases. Cumulative 5-year survival was 91% (endpoint total hip arthroplasty or poor Merle d’Aubigné Score). Long-term results are not available yet.     

Three-dimensional correlation between trochanteric fossa and the ideal entry point for antegrade femoral nailing

PurposeTo verify the practical correlation between the topographical features of the femur neck base and the ideal entry point by analyzing three-dimensional (3D) models virtually implanted with an antegrade femoral nail.Materials and methodsA total of 103 cadaveric femurs (50 males and 53 females) were enrolled. Specimens underwent continuous 1.0 mm slice computed tomography (CT) scans. CT images were rendered into 3D images using image-processing software (Mimics^®) to reconstruct the geometry of the cortex and medullary canal. A real cannulated femoral nail (CFN)^® was processed into a 3D image using a 3D sensor at the actual size and optimally placed in the femur model using Mimics^® for virtual implantation. The correlation between the ideal entry point in the cranial view of the proximal femur and the trochanteric fossa was assessed and overlap of trochanter overhang was verified.ResultsThe entry point of 68 models (66.0%) was the trochanteric fossa, while the others were placed around the anterior border of the trochanteric fossa. The proximal end of the nail overlapped in 50 models (48.1%), and among them, the central point of 23 models (22.3%) was obscured by trochanteric overhang. There was a statistically significant risk associated with female gender (6.02 times) and type IV overhang of Grenchenig’s classification (4.56 times). Despite the precise positioning of the trochanteric fossa, 11 models (10.7%) had the entry point covered by trochanteric overhang.ConclusionThe ideal entry point was over the trochanteric fossa in just half of the models, and could be hindered by trochanteric overhang even though the CFN was ideally positioned.