Objectives

Total hip arthroplasty (THA) is one of the most successful surgical procedures; several bearing technologies have been used, however none of these is optimal. Metal on polycarbonate-urethane (PCU) is a new bearing technology with several potential advantages: PCU is a hydrophilic soft pliable implant quite similar in elasticity to human cartilage, offers biostability, high resistance to hydrolysis, oxidation, and calcification, no biodegradation, low wear rate and high corrosion resistance and can be coupled with large metal heads (Tribofit Hip System, THS).

The aim of this prospective study was to report the survivorship and the clinical and radiographic outcomes and the metal ions dosage of a group of patients operated with metal on PCU arthroplasty featuring large metal diameter heads, at 5 years from surgery.

Background

The aim of this study is to analysis the ability of these patients, treated with MOMHR, to resume sport activities by gait analysis and clinical evaluations. Metal on metal hip resurfacing (MOMHR) is indicated to treat symptomatic hip osteoarthritis in young active patients. These patients require a high level of function and desire to resume sport activities after surgery.

Introduction

The aim of this study was to analyze the results of our series of female patients treated with <48 mm MOMHR devices at a minimum follow-up of 5 years, to understand which is the most important aspects affecting the results and to define if the metal ions dosage has to be indicated as a routinely follow-up.

Introduction

Metal-on-metal hip resurfacing (MOMHR) is a good surgical indication for young active patients. However, it cannot be used in patients with an excessively short femoral head/neck. To address these cases, a new surgical technique has been developed comprising femoral head augmentation using impacted morcellized bone grafts.

Introduction

Metal-on-polycarbonate urethane (MPU) is a cutting-edge new bearing technology for hip arthroplasty. The acetabular component consists of a 2.7mm-thick polycarbonate-urethane liner inserted into a specially manufactured uncemented titanium shell coated with hydroxyapatite [(HA) Fig. 1]. The liner is pliable and biomechanically mimics human cartilage. In vitro studies have shown minimal wear, fluid film lubrication, physiological load transmission and shock absorption capacity equal to the normal hip. This system includes prosthetic heads of a diameter 12mm less than the socket diameter. The aim of this study was to clinically assess patients treated with this novel technology in a retrospective single centre study.

A retrospective single-center review has been performed to gather clinical data on the use of polycarbonate-urethane (PCU) as an articulating bearing material inside a cobalt-chrome (Co-Cr) press-fit acetabular shell.

As of January 2010, the Co-Cr shell and PCU liner have been implanted into 25 total hip patients which were retrospectively followed. The indications for use were in 24 cases of osteoarthritis, and 1 revision case. No patient was lost to follow-up. The average follow-up time was 17.6 months (range 8-27). The average age of these patients was 67.9 (range 44-84), the sex distribution was 14 female and 11 male patients, of whom 15 were right and 10 left side. 24 patients received a total hip replacement with the metal acetabular system and a cementless femoral stem and 1 patient received the metal acetabular shell coupled to a cemented resurfacing head.

None of the cases has had a dislocation, revision, dislodgement, or infection. At follow-up, the mean Harris hip score was 98 points (80-99). X-rays showed good bone-implant contact without any osteolysis or bone rarefaction.

A detailed review of the clinical data of these patients shows that a PCU liner inserted into a Co-Cr acetabular shell is as safe and effective as other commonly used acetabular shells in other total hip systems currently available. No new or unintended adverse or device-related events were discovered with the clinical use of PCU in a Co-Cr acetabular shell.

Although the number of displaced femoral neck fractures treated with hip arthroplasty is steadily growing, the outcomes are not as good as for other surgical indications. As a result, there is no consensus on the ideal type of arthroplasty for these patients. Unipolar and bipolar arthroplasty have a low dislocation rate but implant longevity and functional results are suboptimal. Total hip arthroplasty (THA) provides better functional outcomes and implant longevity but it is associated with a high incidence of postoperative dislocation. This constitutes a significant limiting factor for a more widespread use of this procedure.

The TriboFit^® Buffer (Active Implants Corporation, Memphis, Tennessee, USA) is a 2.7 mm-thick cup made of polycarbonate-urethane which mimics the mechanical characteristics of human cartilage. It is a pliable, hydrophilic, biocompatible, endotoxin-resistant material and acts as a stress-absorber, transmitting loads to the subchondral bone in a physiological manner. The TriboFit^® Buffer shows excellent tribology, including ideal fluid film lubrication, low friction, high load carrying capabilities and long endurance.

The TriboFit^® Buffer is fixed using flexible mechanical fixation. With a special instrument, a circumferential groove is cut into the patients’ socket. The TriboFit^® Buffer is seated by applying gentle pressure, with its ledge snapping tightly into the groove. The surgical technique is bone sparing as no acetabular bone reaming is required whatsoever. The TriboFit^® Buffer can be coupled with large diameter cobalt-chromium femoral prosthetic heads of the same dimensions as the patients’ femoral head. By restoring the correct hip anatomy and preserving the original size of the femoral head, hip range of motion (ROM) and stability are optimised.

Within a multi-centre study, 224 patients (63 male and 161 female) with femoral neck fractures were treated with the TriboFit^® Buffer, a large diameter head and either cemented (192) or uncemented femoral stems (32). The mean patient age was 83 years (range 65 to 96).

All surgeries were performed using a standard antero-lateral approach.

Rehabilitation was fast and weight-bearing was as tolerated by the patients. There were no major complications, and in particular, no postoperative dislocations were reported.

At a mean follow-up of one year, X-rays showed good implant stability. The mean Harris hip score (HHS) after one month was 58 points and increased to 80 points at one year (p = < 0.05). The ROM was the same as in the intact hip. Only one patient was revised because of nonimplant-related pain. This patient complained of pain in the surgically treated limb which was in actual fact related to spinal stenosis. Analysis of the retrieved implant revealed a loss of thickness in the superior area as well as minimal weight (approximately 2.4%). The backside revealed evidence of macroscopic wear in the area of directional loading from the femoral head to the acetabulum. The bearing surface showed minimal wear (less than 15 mm3), indicating that the primary wear location was on the backside. Retrieved synovial fluid and tissue analysis confirmed that there was no reactivity and no sign of synovitis.

With femoral neck fracture patients, TriboFit^® Buffer arthroplasty is theoretically superior to both hemiarthroplasty and THA as it should involve the same low risk of dislocation and acetabular bone preservation associated with hemiarthroplasty, together with the same good functional results and consistent implant longevity of THA. Other advantages of this technique include reduced bleeding and short surgical times.

The results of this study show that the new TriboFit^® Buffer arthroplasty technology has the potential to revolutionize the surgical treatment of displaced femoral neck fracture.

Although metal-on-metal hip resurfacing (MOMHR) is becoming a well accepted indication for young active patients with hip deformities, it does not come without its disadvantages. Longterm bone atrophy, serum metal ion elevation, metal ion hypersensitivity and the formation of pseudotumours have all been reported in the literature. It is thus clear that there is a need for novel bearing technology.

A potentially revolutionary hip resurfacing system comes in the form of the TriboFit^® Hip System, which comprises a 2.7 mm-thick acetabular buffer made of polycarbonate-urethane, a hydrophilic, biocompatible, endotoxin-resistant material which mimics the fluid film layer naturally present in hip joints. This is a pliable implant whose modulus of elasticity is the same as that of normal human cartilage, thus providing optimum shock absorption. In addition, it induces lubrication, which is of the utmost importance as friction is almost eliminated, resulting in a subsequent decrease in the production of wear particles. Indeed, in vitro studies have shown that metal wear is 7-fold less than with a comparable metal-on-metal implant.

The TriboFit^® Buffer is implanted using flexible mechanical fixation. With a special instrument, a circumferential groove is cut into the patients’ socket. The TriboFit^® Buffer is seated by applying gentle pressure, with its ledge snapping tightly into the groove. The surgical technique is bone sparing as no acetabular bone reaming is required whatsoever. The TriboFit^® Buffer can be coupled with a select number of metal hip resurfacing femoral components.

In our centre, we have used this novel bearing technology to treat patients with both osteoarthritis (two patients) and avascular necrosis (four patients). The mean patient age was 50 years (range 30 to 63). In five patients who had a well preserved socket anatomy, the TriboFit^® Buffer was implanted without reaming the acetabular bone. In one patient with significant osteoarthritic changes of the socket, the TriboFit^® Buffer was inserted into a specially manufactured uncemented metal shell, using the TriboFit^® Buffer as a liner. The socket was reamed according to the standard reaming technique. In two patients a Birmingham hip resurfacing (BHR) femoral component was used and in the other four an ADEPT component was used.

Rehabilitation was fast and uncomplicated. The mean follow-up of these patients was one year. The mean preoperative Harris hip score (HHS) was 62. The mean HHS at one year was 99 (p = < 0.05). X-rays showed good quality bone at the bone-implant interface. No osteolysis, loosening, or bone rarefaction was observed. At follow-up, two patients resumed sporting activities. One patient resumed skiing while the other resumed biking.

Our pilot study shows that TriboFit^® Buffer hip resurfacing arthroplasty is a valid alternative to MOMHR. Compared to the latter, the major advantage includes significantly lower metal wear generation, without any differences in the functional results. This new technology has the potential to expand the use of hip resurfacing to patients with renal malfunction, metal ion allergy/hypersensitivity and to fertile females.

Metal-on-metal hip resurfacing (MOMHR) is a good surgical indication for young active patients. However, it cannot be used in patients with severe CDH and in particular a too short head/neck. To address these cases, a new surgical technique consisting of augmentation of the femoral head with impacted morcellized bone grafts has been developed.

32 osteoarthritis patients following severe congenital insufficiency of the femoral head/neck were treated with MOMHR combined with femoral head augmentation. The required amount of augmentation was calculated on preoperative X-rays and confirmed during surgery. Using special instrumentation, bone chips produced while reaming the socket and trimming the head were impacted on the head to achieve the desired reconstruction and lengthening. Finally, the femoral component was cemented.

Mean patient age was 49+ 9 years (18–66). Median head lengthening was 12+ 2 mm. Mean follow up is 4.2 years (3–6). Mean preoperative Harris hip score (HHS) was 58 and at follow-up 95 (p < 0.05). Mean leg lengthening was 2.2 cm (p = 0.001). In all Gruen zones, bone mineral density (BMD) decreased during the first 3 months. At 2 years in zone 1 mean BMD increased to 96.8% (p = 0.009) and in zone 7 to 102.1% (p = 0.05). A correlation was found between valgus positioning of the femoral components and increased BMD (p = 0.005).

This impaction bone grafting technique expands the use of MOMHR to patients with severe congenital hip dysplasia leading to a more anatomical reconstruction with a full recovery of function and BMD.

Metal-polycarbonate urethane (MPU) bearing is a cutting-edge new bearing technology for hip reconstruction. It consists of a 3mm-thick pliable acetabular cup which biomechanically mimics human cartilage and can be coupled with large diameter metal heads. In pristine sockets, no acetabular bone reaming is required to insert the cup. No cement is needed and the cup is simply snapped by hand into a groove made with a special tool. In deformed sockets, the standard reaming technique must be used. The cup acts as a liner inserted into an uncemented metal shell.

MPU bearing has been analysed in comparative in vitro studies. Clinical and radiographic results have been recorded at a minimum follow-up of 2 years in 202 femoral neck fracture patients.

Polycarbonate-urethane elasticity is 20MPa (70 times less than UMHWPE, 10,500 times less than CoCr, p < 0.001). The number of particles generated per step is 1000 with MPU, 1,000,000 with ceramic-ceramic and metal-metal (MOM) (p< 0.001). Fluid film thickness is 0.25microns with MPU, 0.02 with MOM (p< 0.001). At a minimum follow-up of 2 years, X-rays showed good implant stability. In sockets where the buffer alone was implanted an improvement of the supraacetabular bone density was observed over time. Mean Harris hip score after 1 month was 58 points, increasing to 80 points at 2 years (p < 0.05). One patient was revised, due to non-implant-related pain.

The in vitro and clinical data support the use of this novel bearing technology which has the potential to revolutionize hip arthroplasty.

Knowing patient bone density is important to select the proper fixation technique and for secondary osteoporosis medical treatment. However few studies addressing hip fractures provided data regarding patient bone mineral density.

Materials and Methods: Four hundred and thirty three consecutive female patients were included in our study. Inclusion criteria were: AO/OTA fracture type A1, A2 or B, age ? 80 years and minor trauma. BMD values of the lumbar spine (L2–L4) and right proximal femur (neck, trochanter, Ward’s triangle) were measured by dual-energy x-ray absorptiometry. Patients were divided into three groups: Group A had trochanteric fractures (n = 79, average age 85 ? 5), Group B had femoral neck fractures (n = 67, age 84 ? 4) and Group C had no fractures (n = 287, age 82 ? 2). Data was assessed statistically using Analysis of Variance (ANOVA) and receiver operating characteristic (ROC) analysis.

Results: Group A ROC curve had higher values when compared to Group B ROC curve in all corresponding BMD tested sites. Total number of patients with femoral neck fracture and a T-score higher then −2.5 SD were 14 (20.9%), 25 (37.3%) and 16 (23.9%) at the femoral neck, trochanter and at the Ward’s triangle respectively. Patients with a trochanteric fracture and a T-score higher than −2.5 SD were 8 (10.1%), 15 (19.0%) and 12 (15.2%) at the femoral neck, trochanter and Ward’s triangle respectively. BMD values at the trochanteric measurement site demonstrated that the incident rate between the two patient groups differed significantly depending on the diagnosis of osteoporosis (Chi square test: X² = 6.12, p = 0.013).

Discussion: There are notable differences in bone mass density. Femoral neck BMD proved to be the best diagnostic site using DXA, with 15.07% of hip fracture patients having a normal age-related bone mass. Higher non-osteoporotic bone densities were found in women with hip fractures: BMD values were (27.40%) at the trochanter and (17.81%) at the Ward’s triangle.

Conclusions: There was a significant difference between non-osteoporotic related fractures in Group A and Group B. There were more non-osteoporotic related fractures in Group B. A lower BMD was found in patients with trochanteric fractures than in patients with femoral neck fractures. Assessment of bone quality in these patients is of paramount importance in choosing the correct surgical treatment. In patients with poor bone quality, fixation augmentation techniques can be used. We recommend routine DXA scans of the affected fractured hip in all elderly hip fracture patients prior to surgery.

PURPOSE: The treatment of pertrochanteric fractures is constantly evolving and surgical issues remain controversial. Although the use of a sliding hip screw is considered to be the treatment of choice by many surgeons, we believe that intramedullary nailing could be a viable treatment option for unstable pertrochanteric fractures. Given this background, we compared the clinical outcome of unstable pertrochanteric fractures treated with intramedullary hip screw (IMHS) and standard screws with unstable pertrochanteric fractures treated with intramedullary hip screw using hydroxyapatite (HA)-coated screws.

METHODS: Forty consecutive female osteoporotic patients with pertrochanteric fractures were selected. The inclusion criteria were: female; age ≥65 years; pertrochanteric fracture resulting from minor trauma. Patients were randomized by a computer-generated list to receive either IMHS fixed with stainless steel lag screws (Group A) or IMHS fixed with HA-coated pins (Group B).

RESULTS: Average patient age was 82 ± 8 years in Group A and 78 ± 6 years in Group B. Average BMD was 512 ± 177 in Group A, and 471 ± 231 in Group B. Average intraoperative time was 64 ± 6 minutes in Group A and 34 ± 5 minutes in Group B (p < 0.005). In Group A, all patients had post-operative blood transfusions averaged 2.0 ± 0.1. In Group B, there were no blood transfusions (p < 0.0001). In Group A, the reduction over time in the femoral neck-shaft angle was 6 ± 8, while in Group B, the reduction was 2 ± 1 (p < 0.002).

Conclusion: This study showed that intramedullary hip screw with HA-coated lag screw is an effective treatment for unstable fractures in this patient population. The operative time is brief, the fixation is adequate, and the reduction is maintained over time.

Introduction: Pin loosening is a common complication associated with external fixation. Various attempts such as coating the pins with calcium phosphates, have been made to modify the pin surface in order to reduce pin loosening and provide good fixation. Animal and clinical studies showed that fixation using tapered external fixation pins coated with hydroxyapatite is superior to standard pins. However, there is no data on cylindrical pins either fully or partially coated with HA. A partial coating could be a solution to optimize pin fixation with the advantage of easier removal compared to fully coated pins. Our purpose was to compare standard and partially coated cylindrical Apex pins implanted in a sheep model at 2 and 6 weeks. As controls we included fully coated tapered pins.

Materials/Methods: Five groups of pins were studied. Group A included standard cylindrical Apex pins implanted in sheep which were euthanized 2 weeks after surgery; Group B included partially coated Apex pins implanted in sheep which were euthanized 2 weeks after surgery; Group C included tapered pins fully coated with HA implanted in sheep which were euthanized 2 weeks after surgery; Group D included Standard Apex pins implanted in sheep which were euthanized 6 weeks after surgery; Group E included partially coated Apex pins implanted in sheep which were euthanized 6 weeks after surgery. With the tapered pins, full contact between the coated surface and both cortices was obtained. After pin implantation, a unilateral external fixator was mounted onto the pins (Stryker carbon blue monotube Ø 20/250mm). A 5mm long removal osteotomy was performed in the mid-part of the tibial diaphysis, so that 3 pins were situated above the gap and 3 below to ensure load transfer through the bone-pin interface. Extraction torque and tibial torque resistance and histological analyses were obtained after pin removal.

Results: At 2 weeks, mean insertion torque was significantly higher for group C compared to group A (p = 0.03). Mean extraction torque was statistically higher for group B compared to group A (p = 0.001). A statistically significant difference was found in the Pettine index (p = 0.03) between groups A and B. At 6 weeks, no differences in extraction torque were seen.

Discussion: We believe that the partial application of the coating reduced the potential for osteointegration and the ultimate fixation of the coated Apex pins.

INTRODUCTION Metal-on-metal hip resurfacing (MOMHR) has recently been reintroduced as a viable treatment option for young active patients. A short femoral neck and insufficient head are common deformities following CDH, Perthes disease and SFCE. Therefore, severity of these deformities is a contraindication for MOMHR, as contact between the femoral resurfacing component and the femoral head would be inadequate and off-set insufficient.

METHODS 32 patients with severe deformity of the hip were treated with Birmingham hip resurfacing and head lengthening. We used a standard acetabular component in 18 patients and a CDH acetabular component and supplementary screw fixation in 14. Bone chips produced while reaming the acetabulum were impacted on the femoral head to achieve the desired length, as evaluated on pre-op x-rays. Rehabilitation included no weight-bearing for 1 month and partial weight-bearing for another month.

RESULTS Median patient age was 44 years. Median head lengthening was 1.2 cm. Minimum follow-up was 3.1 years, maximum 5.2. Mean Harris Hip Score was 98. At follow-up 82% of the patients were involved in heavy or moderately heavy work. 34% of the patients practiced sports. Co and Cr serum concentrations at 25 months were respectively ng/ml 1.76, and 0.75. DXA analysis of the proximal femur showed complete recovery of BMD in Gruen zone 1 and increased in zone 7 (p= 0.05). There were no major complications.

DISCUSSION AND CONCLUSIONS The absence of major complications and the quality of our results support this technique in young active patients with severe deformity of the hip.

Introduction: Screw loosening is a common complication of osteoporotic fracture fixation leading to implant loosening, fracture malunion and non-union. Because recent animal studies have shown that bisphosphonates improve implant fixation we wanted to assess whether alendronate (ALN) improves screw fixation in a clinical setting of osteoporotic fractures.

Methods: Sixteen consecutive patients with AO/OTA A1 pertrochanteric fractures were selected. Inclusion criteria were: female over the age of 65, BMD T-score less than −2.5 SD. Fractures were fixed with a pertrochanteric fixator and 4 hydroxyapatite (HA)-coated screws. Two screws were implanted in the femoral head (screw positions 1 and 2) and two in the femoral diaphysis (screw positions 3 and 4). Patients were randomized to either postoperative systemic administration of ALN, 70 mg per week for 3 months (Group A) or no ALN. Fixators were removed at 3 months post-op in all patients.

Results: All the fractures healed. No differences in screw insertion torque between the two groups were found. No pin loosening or infection occurred. The combined mean extraction torque of the screws implanted at positions 1 and 2 (cancellous bone) was 3181 ± 1385 N/mm in Group A and 1890 ± 813 N/mm in Group B (p < 0.001). The combined mean extraction torque of the screws implanted at positions 3 and 4 (cortical bone) was 4327 ± 1720 N/mm in Group A and 3785 ± 1181 N/mm in Group B (ns).

Discussion and Conclusion: This is the first study to demonstrate in a clinical setting improved screw fixation following post-operative ALN treatment. We observed a two-fold fixation increase in the screws implanted in cancellous bone. With cortical bone, the difference in screw fixation was less marked. Besides its bone preserving ALN should be recommended as an effective solution to improve fixation in osteoporotic bone.

INTRODUCTION: This prospective randomized study investigated short-term outcomes of cemented vs. HA-coated hip arthroplasty in elderly osteoporotic patients with femoral neck fractures.

METHODS: Forty consecutive patients with femoral neck fractures (AO/OTA fracture type B2 and B3) were randomized to receive either an AHS prosthesis (Group A, n = 22, cemented implant) or a Furlong prosthesis (Group B, n = 18, HA-coated implant). Inclusion criteria were: female age ≥75, fracture resulting from minor trauma, ability to communicate and bone mineral density (BMD) T-score at the contralateral hip lower than −2.5 SD. Subjective assessment was evaluated according to a rating system 0-(unsatisfactory) to 10(satisfactory). Average follow-up was 29 months for Group A and 27 months for Group B.

RESULTS: Average patient age was 75 ± 5 in both groups. There were no differences in ASA scores between the two groups. Surgical time was 77 ± 12 minutes for Group A, and 72 ± 13 minutes for Group B (ns). Harris hip score was 46 ± 36 in Group A and 62 ± 33 in Group B. (p < 0.05). SF-36 was 35 ± 32 in Group A and 54 ± 32 in Group B (ns). Subjective assessment was 5 ± 4 in Group A and 7 ± 3 in Group B (ns). The incidence of death during the follow-up period was 33% in Group A and 15% in Group B. (p < 0.05). One Group A patient underwent revision due to implant loosening. A Furlong prosthesis was successfully implanted in this patient.

DISCUSSION: Although femoral neck fractures in elderly osteoporotic patients are usually treated with cemented arthroplasty, our comparative study showed better results with the Furlong prosthesis, even if statistical significance was reached in only two parameters. The outcomes obtained with the Furlong prosthesis are due to the ability of the HA-coating to bind with osteoporotic bone, thus establishing a stable fixation. Fixation failed in only one cemented implant, but our case number was limited and the follow-up short. Post-op mortality at the time of follow-up was high. This was not unexpected, given the age level and health status of the study groups. This study shows that the HA-coated Furlong prosthesis is a viable option for the treatment of elderly osteoporotic femoral neck fracture patients.

Because of the decreased holding power of the screws, fixation of osteoporotic fractures has a high failure rate (10%–25%). It should also be reported that even if fixation does not fail, several osteoporotic patients with fractures have unsatisfactory functional results due to bony malunion.

Elderly patients with osteoporosis demand better fixation techniques. Treatment goals in this particular patient population include: proper fracture alignment, stable fixation and early rehabilitation. A surgeon should adopt a minimally-invasive technique in order to relieve the patient of physiological stress and allow for full-weight bearing of the fractured limb. Several fixation augmentation techniques have been proposed such as the use of PMMA, calcium phosphate cement, oblique screw insertion and cannulated ported screws.

Our studies indicated that osteoporotic bone fixation can be greatly improved by using implants coated with calcium phosphates such as hydroxyapatite. Hip fractures are the most severe form of fracture in patients with osteoporosis. Cut-out of the load-bearing implant is seen more frequently compared to patients with good bone quality often leading to revision surgery. We compared dynamic hip screw (DHS) fixation with hydroxyapatite(HA)-coated AO/ASIF screws to DHS fixation with standard AO/ASIF screws in osteoporotic trochanteric fractures. One-hundred-andtwenty patients were divided into two groups and randomized to receive 135° 4-hole DHS with either standard lag and cortical AO/ASIF screws (Group A) or HA-coated lag and cortical AO/ASIF screws (Group B). Inclusion criteria were: female, age > 65 years, AO/OTA fracture type A1 or A2 and a bone mass density (BMD) T-score lower than −2.5. Exclusion criteria included lag screw extension into the proximal third of the femoral head. Between the two groups, there were no differences in patient age, BMD, screw position in the femoral head, tip apex distance, quality of reduction and fracture impaction at the 6-month follow-up. In Group A, femoral neck shaft angle (FNSA) reduced over time (134 ± 5° postoperative vs. 126 ± 12° at 6 months, p = 0.003), whereas in Group B, no reduction occurred over time, as indicated by the lack of difference between the FNSA post-operative (134 ± 7°) and at 6 months (133 ± 7°). Lag screw cut-out occurred in four Group A cases but not in Group B (p < 0.05, = 0.8). Three patients with cases of cut-out underwent revision with bipolar prostheses. At 6 months, the Harris hip score was 60 ± 25 (Group A) and 71 ± 18 (Group B) (p= 0.007).

External fixation could be a viable treatment option in elderly trochanteric fracture patients since it typically involves a low energy trauma. However post-operative complications associated with inadequate pin fixation have limited its use. Because of the development of HA-coated screws, we compared external fixation with HA-coated screws (H-CP) to DHS with AO/ASIF stainless-steel screws in osteoporotic trochanteric fractures. Forty patients were divided into two groups and randomized for treatment with either 135° 4-hole DHS (Group A) or external fixation with 4 H-CP (Group B). Inclusion criteria were: female, age > 65 years, AO/OTA fracture type A1–2 and a BMD T-score lower than −2.5. All fixators were removed at 3 months. There were no differences in patient age, fracture type, BMD, ASA, hospital stay and quality of reduction. Average number of blood transfusions was 2 ± 0.1 in Group A, whereas no blood transfusions were required in Group B (p < 0.005). Post-operative FNSA was 134 ± 6 ° in Group A and 132 ± 4° in Group B (ns). In Group A, the varus collapse of the fracture at 6 months was 6 ± 8° and in Group B 2 ± 1° (p = 0.002). The Harris hip score was 62 ± 20 in Group A and 63 ± 17 in Group B (ns). In Group B, no screw infection occurred.

Conclusion: A valuable strategy that will benefit the elderly osteoporotic patient and provide for early mobilization is the use of a minimally-invasive technique, a well-restored anatomy of the fractured limb, no blood transfusion requirements and early rehabilitation. These should also be beneficial for maintaining the overall well-being of the patient. Our results demonstrate that enhanced screw osteointegration and fracture fixation will have a positive impact on the quality of life in the elderly osteoporotic patient.

Purpose: Four external fixation pin types differing in coating, design and implantation technique were tested in an animal study.

Methods: Forty tapered pins were divided into 4 Groups according to pin design type: Group A consisted of 10 standard self-tapping pins (ø5–6mm, pitch 1.75mm), Group B 10 hydroxyapatite (HA)-coated self-tapping (ø5–6mm, pitch 1.75mm), Group C 10 standard, self-drilling, self-tapping (ø5–6mm, pitch 1.25mm) and Group D 10 HA-coated, self-drilling, self-tapping (ø5–6mm, pitch 1.25mm). Four pins were randomly implanted into the femoral diaphysis of 10 sheep. The pins were implanted at 2-cm intervals apart. Pre-drilling was used for Groups A and B but not for Groups C and D. Sheep were euthanized 6 weeks after surgery.

Results: There were no major complications. Mean pin insertion torque was 3100 ± 915 Nmm in Group A, 2808 ± 852 Nmm in Group B, 2589 ± 852 Nmm in Group C and 2180 ± 652 Nmm in Group D. Mean pin extraction torque was 1570 ± 504 Nmm in Group A, 2128 ± 1159 Nmm in Group B, 1599 ± 809 Nmm in Group C and 2200 ± 914 Nmm in Group D. Insertion torque of the coated groups was lower than insertion torque of the standard groups (p < 0.05). However, extraction torque of Groups B and D was higher than Groups A and C (p < 0.05). No differences in pin fixation were found between the two coated pin groups (Group B and D). Morphologic analysis showed extensive bone to pin contact without fibrous tissue interposition in the coated pin groups and fibrous tissue interposition in the uncoated pin groups.

Conclusion/Significance: This study demonstrated that coating pins with hydroxyapatite is effective regardless of the pin design and the implantation technique.

Introduction: Deterioration of bone-pin interface, causing pin loosening and infection, is a major cause of postoperative complications following external fixation. This paper presents the results obtained using hydroxyapatite (HA)-coated pins in various bone types, such as osteoporotic bone.

Materials And Methods; In an animal study comparing HA-coated and standard pins, pin insertion and extraction torque were measured. Subsequently, a clinical study compared insertion, extraction torque and pin-tract infection rate of standard and HA-coated pins implanted in healthy and osteoporotic bone.

Results: hi the animal study, mean final insertion torque was 4360±1050Nmm in the standard group and 3420 ± 676 Nmm in the HA-coated group. Mean extraction torque was 253 ± 175 Nmm in the standard group and 3360 ± 1260 Nmm in the HA-coated group (p = 0.002). In the clinical study on healthy bone, the mean insertion torque was 4130 ± 2160 Nmm in the standard group and 3440 ± 1930 Nmm in the HA-coated group (p = 0.03). The mean extraction torque was 1470 ± 1700 Nmm in the standard group and 5130 ± 2300 Nmm in the HA-coated group (p < 0.001). There were 33 pin-tract infections in the standard group and 20 pin-tract infections in the HA-coated group (p < 0.05, power 0.9). The standard pin group had a mean extraction torque of 730 (0–5500) Nmm in the infected pin-tracks and 2110 (0–7000) Nmm in the uninfected pin-tracts (p < 0.0001). The HA-coated group had a mean extraction torque of 5310 (1000–8000) Nmm in the infected pin-tracts and 5080 (0–8000) Nmm in the uninfected pin tracts (NS). In the clinical study on osteoporotic bone, mean final insertion torque was 461 ± 254 Nmm in the standard group and 331 ± 175Nmm in the HA-coated group (p = 0.01). Mean extraction torque was 191 ± 154 Nmm in the standard group and 600 ± 214 Nmm in the HA-coated group (p < 0.0005). Pin infection rate was greater in the standard group (p < 0.05).

Conclusion: There was no deterioration of the bone-pin interface strength (measured by torque resistance at the time of pin extraction) with HA-coated pins. The improved strength of fixation of the HA-coated pins was associated with a lower incidence of pin-tract infection.

Although dynamic hip screw (DHS) is considered the treatment of choice for pertrochanteric fractures, we theorized that external fixation would produce clinical outcomes equal to, if not better than, outcomes obtained with conventional treatment. As external fixation is minimally-invasive, we expected a lower rate of morbidity and a reduced need for blood transfusions. We compared fixation with DHS vs. Orthofix pertrochanteric fixator (OPF) in elderly pertrochanteric fracture patients. Forty consecutive pertrochanteric fracture patients were randomized to receive either 135A1 4-hole DHS (Group A) or OPF with 4 HA-coated pins (Group B). Inclusion criteria were: female, age B3 65 years, AO type A1 or A2 and BMD less than −2.5 T score. There were no differences in patient age, fracture type, BMD, ASA, hospital stay or quality of reduction. Operative time was 64 B1 6 minutes in Group A and 34 B1 5 minutes in Group B (p < 0.005). Average number of post-operative blood transfusions was 2.0 B1 0.1 in Group A, and none in Group B (p < 0.0001). Pain was measured 5 days post-operatively and was lower in Group B (p < 0.005). Fracture varization at 6 months was 6 B1 8A1 in Group A and 2 B1 1A1 in Group B (p = 0.002). In Group B, no pin-tract infections occurred. Pin fixation improved over time, as shown by pin extraction torque (2770 B1 1710 N/mm) greater than insertion torque (1967 B1 1254 N/mm), (p= 0.001). Harris hip score at 2 years was 62 B1 20 in Group A and 63 B1 17 in Group B. This study shows that OPF with HA-coated pins is an effective treatment for this patient population. Operative time is brief, blood loss is minimal, fixation is adequate and the reduction is maintained over time.