Maximum temperatures of 89°C recorded during the mechanical preparation of 35 femoral heads for resurfacing

Background and purpose

We noticed that our instruments were often too hot to touch after preparing the femoral head for resurfacing, and questioned whether the heat generated could exceed temperatures known to cause osteonecrosis.

Patients and methods

Using an infra-red thermal imaging camera, we measured real-time femoral head temperatures during femoral head reaming in 35 patients undergoing resurfacing hip arthroplasty. 7 patients received an ASR, 8 received a Cormet, and 20 received a Birmingham resurfacing arthroplasty.

Results

The maximum temperature recorded was 89°C. The temperature exceeded 47°C in 28 patients and 70°C in 11. The mean duration of most stages of head preparation was less than 1 min. The mean time exceeded 1 min only on peripheral head reaming of the ASR system. At temperatures lower than 47°C, only 2 femoral heads were exposed long enough to cause osteonecrosis. The highest mean maximum temperatures recorded were 54°C when the proximal femoral head was resected with an oscillating saw and 47°C during peripheral reaming with the crown drill. The modified new Birmingham resurfacing proximal femoral head reamer substantially reduced the maximum temperatures generated. Lavage reduced temperatures to a mean of 18°C.

Interpretation

11 patients were subjected to temperatures sufficient to cause osteonecrosis secondary to thermal insult, regardless of the duration of reaming. In 2 cases only, the length of reaming was long enough to induce damage at lower temperatures. Lavage and sharp instruments should reduce the risk of thermal insult during hip resurfacing.Hip resurfacing can fail due to osteonecrosis (Amstutz et al. 2004, Daniel et al. 2004). Osteonecrosis has been explored by surrogate means. The femoral head is devascularized by the posterior approach (Steffen et al. 2005, Beaule et al. 2006, Khan et al. 2007) and its blood flow is reduced by 50% if the neck is notched (Beaule et al. 2006). Temperatures during femoral head preparation are unknown and could be a cause of osteonecrosis. Temperatures may reach 68°C when cement is polymerizing during resurfacing (Gill et al. 2007).The effect of heat generated in bone at the cellular level is difficult to quantify. The important factors are the peak temperature and the duration of the thermal insult. With higher temperatures, a shorter exposure is needed to cause injury (Lundskog 1972, Berman et al. 1984). Thermal insult of 47°C for 60 s is the threshold for bone injury (Ericksson and Albrektsson 1983). Exposure to 50°C for 30 s causes widespread injury to bone 1 mm from the point of exposure (Lundskog 1972) and 55°C for 1 min causes marrow necrosis (Berman et al. 1984). Bone alkaline phosphatase is denatured at 56°C (Posen et al. 1965). When bone reaches to a temperature of 70°C or more, macroscopic bone necrosis can be seen intraoperatively. Cell necrosis occurs at temperatures of 70°C within 1 s (Moritz and Henriques 1947). There is histological evidence of bone necrosis after exposure to 70°C for 1 min (Berman et al. 1984) and 80°C for 5 s (Lundskog 1972).We noticed that our instruments were often too hot to touch after preparing the femoral head for resurfacing and wondered whether the heat generated during femoral head preparation might exceed the temperatures known to cause osteonecrosis.     

Vasculature deprivation-induced osteonecrosis of rats’ femoral heads associated with the formation of deep surface depressions

Background Shallow or deep bowl-shaped depressions often develop after drilling an intraosseous conduit in the necrotic, avascular femoral head of rats. The etiopathogenesis of tissue loss at the articulation surface after a drilling procedure was elaborated in the authors’ previous reports. Goals To scrutinize a large collection of femoral heads of rats in order to search for similar changes in cases in which no drilling procedure was carried out. Study This retrospective study comprised the specimens of 386 rats with vessels-deprived osteonecrosis of the femoral heads, none of the animals having undergone a drilling procedure. Results Shallow or deep bowl-shaped depressions were encountered at an incidence as low as 2.8% of the femoral heads of the above mentioned 386 rats. It is not feasible to distinguish histologically the “spontaneously” arising from and drilling-related depressions. Conclusions No assured explanation can be offered for the evolving depressions of the surface of femoral heads of rats, which have not undergone a drilling procedure. It is hypothesized that the synovial fluid forces its way via slits in the articulation surface and bores cavities in the substance of femoral heads, which display a postosteonecrotic osteoarthritis-like disorder. The rising pressure in the arthritic joints results, firstly, in an enlargement of these cavities and, secondly, loss of fibro-cartilaginous tissue such that the cavities come to communicate with the articular space.     

Valgus intertrochanteric osteotomy with single-angled 130° plate fixation for fractures and non-unions of the femoral neck

Non-union of femoral neck fractures may occur due to mechanical and biological factors. Valgus intertrochanteric osteotomy (VITO) alters hip biomechanics and enhances fracture union. The double-angled 120° plate is usually used for internal fixation of the osteotomy. It allows the osteotomy to heal with medialisation and verticalisation of the femoral shaft. This deformity causes medial ligament strain of the knee joint, genu valgum and ultimately osteoarthritis. This work presents our experience in treating vertical fractures and non-unions of the femoral neck by VITO and fixation by a single-angled 130o plate. Thirty-six patients presented with 19 recent vertical femoral neck fractures, and 17 non-unions were included. They were 26 men and ten women, and their ages averaged 37 years. Preoperative planning and VITO technique are described. Union was achieved in 35 patients (97%), and one recent fracture failed to unite (3%). Time to fracture union averaged four months in recent fractures and eight months in un-united fractures. All patients with united fractures had an almost normal configuration of the upper femur. Avascular necrosis of the femoral head was reported in five patients. Twenty-two patients (61%) were pain free, nine (25%) had hip pain on lengthy walks and the remaining five (14%) had persistent pain. Preoperative limb shortening averaged 2.5 cm, and post-operative shortening averaged 0.5 cm. We recommend VITO and fixation by a single-angled 130o plate for vertical femoral neck fractures and non-unions in relatively young adult patients.     

How precise is the identification of the center of the femoral head during total knee arthroplasty?

Background and purpose

Identification of the center of the femoral head in the coronal plane is essential during total knee arthroplasty. We evaluated a new method for localization of the center of the hip, thereby detecting the neutral mechanical axis using inter-femoral head center distances (X) measured from a radiograph. Our proposed method was compared with 3 commonly used methods using landmarks that are estimated to be 2 finger-breaths medial to the anterosuperior iliac spine (method A), 2.5 cm perpendicular to the mid-inguinal point (method I), and 1.5 cm lateral to the femoral artery (method F).

Methods

114 patients undergoing total knee arthroplasty were prospectively enrolled in the study. Four landmarks were marked and conventional anterior-posterior pelvic radiographs were taken. On the radiograph, the distance between the estimated FHC and the neutral mechanical axis was measured.

Results

The median value (mm) of the measured distance was 9 in A, 7 in I, 8.5 in F, and 5 in X. When an error of more than 3° from neutral alignment was defined as an outlier, 15% of measurements in A, 6% of measurements in I, 14% in F, and 2% in X would fall in the outlier zone.

Interpretation

The method detecting the neutral mechanical axis using inter-femoral head center distances (X) showed the least variability and the lowest percentage of outliers.Correct alignment is important for the longevity of total knee arthroplasty (TKA) (Jeffery et al. 1991, Ritter et al. 1994, Ensini et al. 2007, Sikorski 2008). Location of the center of the femoral head (FHC) intraoperatively is useful in assessment of the overall alignment of the lower limb during TKA. By estimating the mechanical axis after placement of the trial components, errors of limb alignment can be identified and corrected.Ideally, the FHC can be identified by an on-table radiograph, which, however, is time consuming and inconvenient and exposes the patient to additional radiation. Navigation systems have become more widely used to find the FHC and they may improve the accuracy of alignment, but this approach is not always available. Palpation of the anterior iliac spine (ASIS) is commonly used intraoperatively to indirectly estimate the center of the femoral head (Horton and Reckling 1995, Hooper et al. 2005). However, some authors have suggested that this is not as accurate as it is commonly presumed to be (Mullaji et al. 2010, Baldini and Adravanti 2008). Various methods using anatomical landmarks have been reported as alternatives (Horton and Reckling 1995, Matsuda et al. 2004, Sawant et al. 2004, Samarji et al. 2009). They include the use of a landmark that is located 2 finger-breaths medial to the ASIS (method A) (Hooper et al. 2005), a landmark that is located 1.5 cm lateral to the point where the femoral artery crosses the line joining the pubic tubercle and the ASIS (method F) (Sawant et al. 2004), and a landmark that is located 2.5 cm perpendicular to the midpoint of the line joining the ASIS and the symphysis pubis (method I) (Samarji et al. 2009).Here we describe a new method (X) for localization of the FHC using the inter-femoral head center distance (IFD). The IFD was measured on an anteroposterior radiograph of the pelvis preoperatively. A customized metal graduated ruler with 2 mobile pegs was used to replicate the IFD, and this ruler was fitted above the pelvic girth. Thus, these 2 pegs indicated the FHC and then we could identify the neutral mechanical axis of the lower limb.In this study, we validated the reliability of method I in identifying the neutral mechanical axis of the lower limb in vivo, and compared the precision of the methods using A and X. We also evaluated the 2 techniques using F and I. In addition, we tried to determine whether height, body mass index (BMI), and abdominal circumference had any influence on the 4 methods.     

Screw-plate angulation of 130° or 135° and 120° in the stabilization of an unstable trochanteric femoral neck fracture

Correct positioning of the screw in the femoral head is the most important surgical challenge after the external reduction of an unstable femoral neck fracture. Rules of this challenge are very accurate, especially for osteoporotic elderly patients. We would like to point out the relationship between anatomy, mathematical pattern, and surgical procedure. Anatomically, the correct position for the screw must be in the lower half of the femoral head. From a mathematical point of view, in this position, the portion of a sphere's surface is higher and its volume is the highest. In some cases therefore, it is not technically possible to fix in good position the 130°or 135° screw. It could be of interest to provide surgeons with a 120° angulation screw-plate.     

LCP 140° Pediatric Hip Plate for fixation of proximal femoral valgisation osteotomy

Purpose

Femoral osteotomy is one of the most widely performed reconstructive operations in pediatric orthopedic surgery. Many implants for fixation have been used, but so far there is no literature about the application and outcome of the LCP 140° Pediatric Hip Plate for proximal femoral valgisation in children.

Methods

Data of patients with a valgisation of the proximal femur using the LCP 140° Pediatric Hip Plate between February 2011 and July 2012 were retrospectively collected and analyzed.

Results

We included 10 patients (11 hips) with a mean follow-up of 15.3 ± 6.3 months (range 5.6–23 months). The mean age was 9.6 ± 1.2 years (range 7.3–11.8 years) with a mean hospital stay of 5.2 ± 1.7 days (range 3–9 days). Callus formation was observed in all cases at 6 weeks postoperative control and consolidation was shown after a mean time of 14.1 ± 2.3 weeks (range 12.1–19.1 weeks). There was no delayed union or any case of non-union in our series. The stability of the operative reduction including the corrected neck-shaft angle (mean 19° ± 7.9°; range 10.5°–38.5°) was maintained during the follow-up period. No cases of recurrence (varisation) or complications requiring further treatment or revision were observed.

Conclusions

In our series, the 140° LCP Pediatric Hip Plate was shown to be safe and applicable in the clinical setting with good results. We therefore consider this device to be valuable for the correction of pathologic varus conditions of the proximal femur in children.     

Expandable proximal femoral nails versus 95° dynamic condylar screw-plates for the treatment of reverse oblique intertrochanteric fractures

The treatment of a simple (AO/OTA classification 31A3.1) reverse oblique intertrochanteric hip fracture is a challenge for the orthopaedic surgeon. The surgical options include the use of side plates with various angled leg screws or intramedullary devices. The purpose of this study was to retrospectively assess our results of treating reverse oblique fracture with an expendable proximal femoral nail (EPFN) or with a dynamic condylar screw-plate (DCS: 95°) between January 2006 and July 2009. Thirty-three patients (6 males and 27 females, mean age 78 years) met the study inclusion criteria and comprised the two study groups: 19 had been treated by EPFNs and 14 had received DCSs. They were followed for a mean of 28 months (range 6-47). Eight patients (5 EPFN and 3 DCS) died during the follow-up period from causes not related to the operation. Two ESPN patients and 5 DCS patients had malunions. Functional outcome scores showed better results in the EPFN group, but the difference was statistically significant only for the sitting subcategory (p=0.04). Based on our results and experience, we propose that the EPFN is at least as good as the DCS for treating reverse oblique fractures of the femur.     

Hemiarthroplasty of the hip for fracture-what is the appropriate sized femoral head?

INTRODUCTION: Caliper measurement of the excised femoral head is a standard technique for determination of prosthetic head size during hemiarthroplasty for displaced femoral neck fractures. OBJECTIVES: To evaluate the accuracy of the caliper method of hemiarthroplasty head sizing by comparing it to the native joint congruency (JC) at the weight bearing surface. MATERIALS AND METHODS: The diameters of femoral heads in 10 cadaver hip joints were measured by using a caliper at the head equator. Cast moulds were prepared from both the acetabulum and the femoral head in each joint. Every mould's exact spherical diameter at the weight bearing region was measured by a computerised coordinate measuring machine (MNC B231 MITUTOYO). All specimens were coded to ensure that future examination was carried out in a blind manner. Native JC mismatch was determined by subtracting the diameter of the femoral cement mould from that of the acetabular one. Similarly, JC mismatch was calculated for the caliper measurements. RESULTS: The average native JC mismatch (0.36+/-0.29mm, range 0.03-0.82mm, median 0.29mm) was found significantly smaller (p=0.03) than following caliper measurements (0.72+/-0.37mm, range 0.37-1.46mm, median 0.6mm). Routine caliper measured downward size rounding enhanced (p=0.004) this mismatch (0.98+/-0.44mm, range 0.37-1.96mm, median 1.01mm), while upward rounding (0.48+/-0.46mm, range -0.06 to 1.15mm, median 0.41mm) helped mitigate this tendency. CONCLUSIONS: Caliper measurements tend to undersize the actual sphere diameter of the femoral head at the weight bearing region. Upward rounded prosthesis should be selected in order to compensate for this propensity.     

Case reports - Injury to the deep femoral artery during proximal locking of a distal femoral nail–a report of 2 cases

No Abstract available.     

Proximal femoral replacement: A salvage treatment of cephalomedullary nails’ mechanical failures in the elderly population

BackgroundThe use of proximal femoral replacements (PFR) has been recently described for catastrophic internal fixation failures. PFR is an attractive treatment option because it is technically straightforward and allows for immediate mobilization of the patient. The aim of the study was to determine the survivorship, functional outcome and complications’ rate in a group of elderly patients who underwent proximal femoral replacement as a salvage treatment after femur cephalomedullary nails’ mechanical failures.MethodsWe evaluated 21 patients who underwent salvage of a failed cephalomedullary nail by using a single design PFR at our institution between 2014-2017. A cemented stem was used in all cases. Radiographs were assessed for fractures, sign of loosening, presence of heterotopic ossification and leg length discrepancy. Functional evaluation was performed through Harris Hip Score (HHS), FIM™ and Time Up and Go test (TUG). Kaplan-Meier estimator was used to determine the overall implants’ survival.ResultsThe average age at the time of surgery was 83years. The mean follow-up was 3.1years. We recorded 3 dislocations of which 2 required a revision. No case of septic or aseptic failure was reported. Two patients died respectively at 11 and 14 months after surgery. At the last follow-up the mean HHS, FIM™, and the TUG improved significantly (p<0.05).ConclusionImmediate weight bearing, good functional outcomes, low complications’ and one-year mortality rate make the proximal femur replacement with megaprostheses a potential first line treatment of intertrochanteric/subtrochanteric fixations’ failures among elderly, osteoporotic, frail patients. Dislocation is the most common complication to bear in mind within the first six months after surgery.     

Osteonecrosis of the femoral head after osteosynthesis of a proximal femur fracture with a 95° condylar plate

Summary Avascular necrosis of the femoral head is a frequent complication after osteosynthesis of femoral neck fractures. It is rarely seen after proximal femur fractures with intact trochanteric area. The choice of the implant varies from different blade systems (DHS, DCS and condylar plates) to intramedular nailing systems (gamma nail, classic nail). The complication of avascular necrosis of the femoral head after internal fixation of subtrochanteric and proximal femur fractures is reported following intramedullary nailing. We report a case of a femoral head necrosis after osteosynthesis of a proximal femur fracture with a 95 degree condylar plate.      

Osteonecrosis of the femoral head after osteosynthesis of a proximal femur fracture with a 95° condylar plate

Avascular necrosis of the femoral head is a frequent complication after osteosynthesis of femoral neck fractures. It is rarely seen after proximal femur fractures with intact trochanteric area. The choice of the implant varies from different blade systems (DHS, DCS and condylar plates) to intramedular nailing systems (gamma nail, classic nail). The complication of avascular necrosis of the femoral head after internal fixation of subtrochanteric and proximal femur fractures is reported following intramedullary nailing. We report a case of a femoral head necrosis after osteosynthesis of a proximal femur fracture with a 95 degree condylar plate.     

Do large femoral heads reduce the risks of impingement in total hip arthroplasty with optimal and non-optimal cup positioning?

The purpose of this study was to assess whether large femoral heads (36–38 mm) improve the range of motion in total hip arthroplasty compared to standard (28–32 mm) femoral heads in the presence of optimal and non-optimal cup positioning. A mathematical model of the hip joint was generated by using a laser scan of a dried cadaveric hip. The range of motion was assessed with a cup inclination and anteversion of reference and with non-optimal cup positions. Large femoral heads increased the range of motion, compared to the 28-mm femoral head, in the presence of a hip prosthesis correctly implanted and even more so in the presence of non-optimal cup positioning. However, with respect to the 32-mm femoral head, large femoral heads showed limited benefits both in the presence of optimal and non-optimal cup positioning.     

Remodeling of the proximal femur after upper femoral varus osteotomy for the treatment of Legg-Calvé-Perthes disease

Upper femoral varus osteotomy of the proximal femur without rotation has been the surgical treatment of choice by the senior author (D.S.W.) in 124 cases of Legg-Calve-Perthes disease. There have been no previous studies documenting the nature of the remodeling process after this surgical procedure. The authors analyzed the radiographic changes that occur over time at the osteotomy site and the angle of inclination (neck-shaft angle). Inclusion criteria were a minimum of 2 years of radiographic follow-up. Patient follow-up ranged from 2 to 7 years (average 5.3 years). Goniometric measurements were performed at the osteotomy site as well as on the neck-shaft angle on preoperative, postoperative, and yearly AP radiographs. Results were recorded with reference to the percentage of correction per year. The authors also compared the results of patients younger than 8 years of age (group 1) with those older than 8 years of age (group 2). The average percentage of remodeling at the osteotomy site was 60% at 6 years, with 40% of the correction occurring within the first 2 years. The neck-shaft angle remodeled in a similar fashion: there was approximately two-thirds correction by 7 years, with most correction being evidenced within 3 to 4 years. There was no significant difference in remodeling based on the age of the patient at presentation. In conclusion, radiographically significant remodeling is to be expected after femoral varus osteotomy despite the diseased proximal femoral epiphysis.     

Surgical treatment of intraparenchymal hemorrhage during mechanical circulatory support for heart-failure – a single-centre experience

Background

Cranial intraparenchymal hemorrhage represents a critical complication of mechanical circulatory support requiring constant antithrombotic treatment. Surgery of intraparenchymal hemorrhage under anticoagulation represents a challenge and imposes significant risks for patients. It was the aim to analyse surgical and clinical outcome of patients requiring surgical treatment due to intraparenchymal hemorrhage.

Methods

Patients with mechanical circulatory support requiring surgical therapy due to space-occupying lobar supratentorial or infratentorial hemorrhage from January 1, 2009 to January 1, 2014 were included in our study. Baseline parameters are preoperative International Normalized Ratio (INR) values, postoperative anticoagulation regiment, bleeding size and localization. Co-primary outcome parameters were the extent of hematoma evacuation and the Modified Rankin Scale at discharge from hospital. Secondary outcome parameters included rate of recurrent hemorrhage, rate of revision surgery and in-hospital mortality.

Results

Twelve patients (mean age 44?±?18 years, nine supratentorial-/three infratentorial hemorrhages, 11 left ventricular assist devices, and one extracorporeal membrane oxygenation) were included. Surgical hematoma evacuation was performed in 11 patients, one patient received decompressive hemicraniectomy. Hematoma evacuation was complete in no patients, and partial in 11 patients. Initial INR was 2,7?±?1,6. Rate of recurrent hemorrhage was 75 %. Revision surgery was performed in three patients achieving partial hematoma evacuation in two patients and complete evacuation in one patient. Modified Rankin Scale at discharge from hospital was six in nine patients (in-hospital mortality of 75 %), five in two patients and four in one patient.

Conclusions

Surgical treatment of life threatening, space-occupying intraparenchymal hemorrhage under mechanical circulation support is of limited efficacy with high rates of recurrent hemorrhage and in-hospital mortality. We provide additional data that postponing anticoagulation is feasible and may lead to improved clinical outcome and survival.