Hardware removal: indications and expectations

Femoral neck fracture after removal of the compression hip screw from healed intertrochanteric fractures

OBJECTIVES

To evaluate the incidence of femoral neck fracture (FNF) after removal of a compression hip screw (CHS) without trauma and to determine the risk factors for this type of fracture.

DESIGN

Retrospective study of consecutive patient series.

SETTING

University teaching hospital.

PATIENTS

Sixty-seven patients with a mean age of 65.3 years (45 women and 22 men).

INTERVENTION

A total of 67 implants were removed in the presence of bony consolidation of the fracture site; most of them were due to hardware pain.

MAIN OUTCOME MEASURES

The incidence of FNF after a CHS removal, clinical parameters (age, gender, bone mineral density, body mass index, and fracture stability), and radiologic parameters (the femoral neck-shaft angle, femoral neck width, distance between thread of lag screw, and neck cortex). Univariate analysis was performed for those parameters of the fracture group and the nonfracture group. To assess which variables were associated with FNF, a multiple logistic regression was used.

RESULTS

Six (9.0%) FNFs occurred within 1 month after a CHS removal. The mean anterior and lateral neck widths were significantly smaller, and the mean anterior and inferior thread-to-cortex distances were significantly shorter in the fracture group compared with the nonfracture group. The risk factor significantly associated with FNF was the inferior thread-to-cortex distance (odds ratio, 0.462; 95% confidence interval, 0.217-0.988).

CONCLUSIONS

CHS should not be removed routinely due to the risk of FNF. Furthermore, attention should be paid to at-risk patients with a hip screw positioned close to the inferior femoral neck cortex.

LEVEL OF EVIDENCE

Prognostic level II.

Novel technique for removal of a broken intracortical screw during THA

Most reports regarding hardware removal involve the violation of the cortex to allow a specialized to tool to extract a retained fragment. This leaves large, unfilled screw holes that act as stress risers for months postoperatively. This article describes a novel technique to remove a retained intracortical screw fragment during total hip arthroplasty. Conversion of an intertrochanteric osteotomy to a total hip arthroplasty can be made more difficult by anatomical changes to the femur and retained hardware. Direct access to the intramedullary canal during total hip arthroplasty allowed for the safe removal of a retained intracortical screw using this technique.

Short stem option for total hip arthroplasty with retained hardware

The presence of retained femoral hardware, usually as a consequence of prior orthopedic trauma, has been classically presented as something that must be removed prior to total hip arthroplasty. However, hardware removal is not without risks, including pain, creation of stress risers, and refracture. The authors report a patient with a retained retrograde femoral nail who underwent total hip arthroplasty with a short, neck-preserving femoral stem used to avoid the need for hardware removal. Clinical results at short-term follow-up have been excellent. In the setting of retained hardware, the use of short stems may be a viable treatment option for a well-selected subgroup of patients who require total hip arthroplasty and when the surgeon cannot use standard implants.

Difficulties in removal of the titanium locking plate in Japan

OBJECTIVE

This study was designed to evaluate the frequency of intraoperative complications associated with titanium locking compression plate (LCP) removal.

DESIGN

Retrospective study.

METHODS

Medical records were reviewed for surgical technique, plate types used, position and number of screws, time from internal fixation to plate removal, and intraoperative complications. Radiographs were reviewed to evaluate the position of the plates and screws and the accuracy of the screw direction. Mann-Whitney and Yates Chi-square tests were calculated with the level of significance at P < 0.05.

RESULTS

All LCPs could be removed. Of the 342 locking head screws (LHSs), a total of 21 (6.1%) screws, 3 (2.0%) 5.0 mm screws (3/153) and 18 (10.7%) 3.5 mm screws (18/169), were difficult to remove. The frequency of difficulty associated with the 3.5 mm LHSs was significantly higher than that of the 5.0 mm LHSs (P < 0.01). The frequency of difficulty associated with the removal of LHSs at the diaphysis was higher than that of LHSs at the epiphysis (P < 0.01), especially with 3.5 mm LHSs. The mean age was significantly lower in the patients in whom removal was difficult (P < 0.05). Our analysis revealed that the frequency of removal difficulty was high when a 3.5 mm LHS was inserted into the diaphysis of young patients.

CONCLUSIONS

We should recognize that the removal of LCPs can involve numerous problems and great care should be exercised, especially in cases involving 3.5 mm LHSs.

A novel technique for pediatric femoral locked submuscular plate removal: the 'push-pull' technique

Submuscular and minimally invasive plate insertion is gaining popularity reducing the need for large open approaches and resulting in a smaller operative ‘footprint.’ With pediatric fractures and titanium implants, fibrous and osseous ingrowth to the implant and osseous implant integration may interfere with implant removal. Therefore, the small minimally invasive implant insertion procedure may require a large maximally invasive exposure for implant removal after fracture healing. To reduce soft tissue damage, bleeding, scarring, and pain associated with implant removal, a minimally invasive procedure utilizing the pre-existing incisions while controlling the implant is efficient and beneficial. The surgical technique is described, and a case series of 21 treated pediatric femoral fractures illustrates the successful performance of the procedure and its limitations.

Technical complications during removal of locking screws from locking compression plates: a prospective multicenter study

PURPOSE

To assess the risk for technical complications in patients undergoing removal of locking compression plates (LCP) with head locking screws.

METHODS

A total of 205 patients who were scheduled for implant removal surgery after a healed fracture of the femur, tibia, humerus, distal radius, or clavicle in nine Austrian clinics were prospectively included in the study, all of whom had previously undergone fracture fixation by plates, with titanium implants used in 98 % of the patients. Intraoperative technical complications and the methods used to solve them were documented by the surgeon.

RESULTS

During the course of this study, a total of 1,462 locking screws were removed from 204 LCPs. While 95 % of these screws could be removed without difficulties, technical complications were reported for 41 patients with 78 screws which could not be removed with standard screwdrivers and required the use of additional instruments. The estimated risk for the occurrence of at least one technical complication during implant removal surgery was 20.1 %. The most frequently observed complications were screws that could not be loosened because they were jammed in the LCP, screws with a damaged recess in which the screwdriver turned freely, as well as a combination of both events. The majority of these screws could be removed with the use of a conical extraction screw or by drilling off the screw head. In one patient, an intraoperative refracture of the humerus occurred during plate removal. Even though there is a rate of 20 % for technical complications when removing the implants, only a few patients experience a clinical impact.

CONCLUSIONS

Titanium LCPs are prone to technical complications during implant removal, but the majority of the issues can be solved using special techniques.

Arthroscopy combined with hardware removal for chronic pain after ankle fracture

PURPOSE

The purpose of this study was to evaluate the effectiveness of arthroscopy combined with hardware removal for chronic pain after satisfactory healing of an ankle fracture. We hypothesized that combining hardware removal with arthroscopy for the intra-articular pathology would improve residual complaints more so than hardware removal alone.

METHODS

The outcomes of the 53 young male patients with chronic pain after healed ankle fracture treated with two different therapeutic plans: (1) conservative treatment after hardware removal (group A) and (2) arthroscopic intervention with hardware removal (group B) were prospectively studied. Patients were reviewed preoperatively and 6 and 12 months postoperatively using American Foot and Ankle Society (AOFAS) scale.

RESULTS

Median AOFAS scores improved from 74 (66-80) points to 76 (73-92) points in group A and from 75 (64-80) points to 85 (72-100) points in group B, and this improvement was significantly higher for patients in group B (p = 0.001).

CONCLUSIONS

This study supports the notion that when there is a definite diagnosis such as loose body, bony impingement, or anterolateral soft-tissue impingement causing chronic pain after healed ankle fracture, arthroscopic treatment with hardware removal is a better treatment option than hardware removal and conservative treatment.

Treatment of type C pilon fractures by external fixator combined with limited open reduction and absorbable internal fixation

INTRODUCTION

This study was conducted to evaluate the clinical outcome of the treatment of type C pilon fractures by using an external fixator combined with limited open reduction and absorbable internal fixation.

PATIENTS AND METHODS

Twenty-five type C pilon fractures, including 4 open fractures, were included in this retrospective study. The procedure of first-stage manipulation and external fixation spanning the ankle joint was conducted as early as possible. For the second stage, the tibial and fibular fractures were reduced and fixed with absorbable screws or rods through a limited incision. Clinical and radiographic evaluations were performed. The American Orthopaedic Foot & Ankle Society score (AOFAS) was obtained for evaluation of function. Twenty-one patients were followed postoperatively for a minimum of 18 months.

RESULTS

The mean time of union was 4.8 months. Delayed union of the distal tibia occurred in 1 patient. Minor infection occurred in 8 patients and deep infection in 1 patient. No skin necrosis, malunion, loss of reduction, nonunion, or fixation failure was observed during the follow-up period. No hardware removal was needed, nor was adverse tissue reaction to the implants observed. An excellent or good AOFAS outcome was obtained in 81% (17/21) of the patients.

CONCLUSIONS

External fixator combined with limited open reduction and absorbable internal fixation was a reliable treatment for closed and open AO/OTA type C pilon fractures of the distal tibia.

Surgical release of elbow stiffness after internal fixation of intercondylar fracture of the distal humerus

BACKGROUND

Loss of motion is common after intercondylar fracture of the distal humerus despite proper management. The purpose of the current study was to report the results of contracture release for stiffness that developed after open reduction and internal fixation (ORIF) of distal humeral intercondylar fractures.

METHODS

Twenty-four consecutive patients with a stiff elbow after ORIF of intercondylar fractures (20 AO type C2 and 4 type C3 fractures) were managed with contracture release at a median of 13 months. The surgical indication was total arc of motion of less than 100° despite physical therapy for more than 6 months. Plates and screws for ORIF were removed concomitantly in 16 patients. Each patient was evaluated by final arc of motion and Mayo Elbow Performance Score (MEPS).

RESULTS

The main lesions causing stiffness were heterotopic ossification or excessive callus in 13 patients and capsular fibrosis in 11. The mean total range of motion (ROM) was improved from 60.2° preoperatively to 104.8° postoperatively. At the final follow-up, 17 of the 24 elbows (71.8%) obtained a total ROM of more than 100°. The mean MEPS improved from 69 points preoperatively to 87 points at the final follow-up (P < .05). Refracture occurred during ROM exercise in 4 patients who had undergone concomitant implant removal during the contracture release.

CONCLUSION

Surgical release of a stiff elbow that develops after ORIF of intercondylar fractures can result in satisfactory restoration of ROM in most patients. However, potential risk of refracture after release should be considered when implants are concomitantly removed.

Surgeon perceptions and patient outcomes regarding proximal ulna fixation: a multicenter experience

BACKGROUND

Our objective was to determine surgeon- and patient-based perceptions concerning proximal ulna fixation, including rates of implant removal and overall satisfaction.

METHODS

Orthopedic surgeons were surveyed about surgical experience managing proximal ulna fractures and their perception regarding implant removal/revision. A retrospective chart review identified all patients who underwent fixation for proximal ulna fractures and osteotomies between January 2004 and December 2008.

RESULTS

In total, 583 surgeons responded to the survey (80%). Of these, 67% believed that their implant removal rate was the same as other surgeons whereas 31% believed that their rate was lower. Seventy-one percent believed that patients required hardware removal less than 30% of the time. Ninety-eight percent believed that they were the same surgeons to remove the implant. In total, 138 consecutive patients were surveyed about their proximal ulna implant. Plating was performed in 80 (58%), and tension banding was performed in 55 (40%). The overall rate of implant removal was 64.5% (89 of 138) at 18.8 months. A second surgeon performed the removal in 68 patients (76%). Of the 49 patients without implant removal, 11 (22%) reported satisfaction with the implant and 19 (39%) reported a functional impairment because of the implant. If guaranteed a safe surgery, 36 (73%) would have the implant removed.

CONCLUSION

Surgeons underestimate the rates of proximal ulna implant removal and patient dissatisfaction. Because 76% of the implant removals were performed by a second surgeon, in sharp contrast to the surgeon-perceived rate of 2%, we challenge surgeons to become more aware of this problem in their practices.

Implant-related fractures in children: a 15-year review

BACKGROUND

To our knowledge, there are no comprehensive clinical studies of implant-related fractures in children. Our goal was to identify the incidence, skeletal location, and associated diagnoses of implant-related fractures.

METHODS

We reviewed our institutional database to identify cases of implant insertion (7584 cases) in patients less than 18 years old from January 1, 1995 through December 31, 2009. We calculated the overall incidence of these fractures and stratified the incidence by skeletal location and preoperative diagnoses. Fisher exact test was used to ascertain differences in fracture incidence. Risk ratios were calculated when appropriate. Significance was set at P<0.05.

RESULTS

There were 25 cases of implant-related fractures: 22 in the femur, 2 in the tibia, and 1 in the radius. The overall incidence of implant-related fracture was 0.33%; the incidence by skeletal location was: femur, 0.89%; tibia, 0.1%; and radius, 0.14%. Associated diagnoses were cerebral palsy (9 cases), hip dysplasia (3 cases), spina bifida (2 cases), and avascular necrosis (1 case); 10 cases were associated with "other diagnoses," which included various skeletal syndromes (5 cases) and traumatic fractures (5 cases). The incidences of implant-related fractures by diagnoses were: cerebral palsy, 1.1%; hip dysplasia, 1.1%; spina bifida, 1.3%; and avascular necrosis, 0.35%. The incidence of implant-related fracture in the "other diagnoses" group was 0.16%, and the incidence of fracture in otherwise healthy patients was 0.084%. The femur was 15.2 times more likely to fracture than other bones (P<0.001). Diagnoses of cerebral palsy, hip dysplasia, spina bifida, and avascular necrosis were 6.1 times more likely to be associated with implant-related fractures than the "other diagnoses" (P<0.001). The mean time to fracture in the study was 2.8 years. The overall implant removal rate at our institution was 24.3%, and it varied significantly by patient diagnosis (P<0.01).

CONCLUSIONS

Skeletal location and preoperative diagnosis should be factors of consideration in a surgeon's decision about removing implants to prevent implant-related fractures.

LEVEL OF EVIDENCE

Prognostic Level III.

Difficulties encountered removing locked plates

INTRODUCTION

Locked plates are commonly used to obtain fixation in periarticular and comminuted fractures. Their use has also gained popularity in repairing fractures in osteoporotic bone. These plates provide stable fixation and promote biological healing. Over the last 3 years, we have used over 150 locked plates with varying success to fix periarticular fractures involving mainly the knee and ankle. In this study, we report our clinical experience and the difficulties encountered when removing locked plates in adult patients with a variety of indications including implant failure, infection, non-union and a palpable symptomatic implant.

METHODS

A retrospective analysis was performed of patients enrolled prospectively into a database. Included in the study were 36 consecutive adult patients who each underwent the procedure of locked plate removal in a single inner city level 1 trauma centre. Data collected included primary indication for fixation, indication for implant removal, time of the implant in situ, grade of operating surgeon and difficulties encountered during the procedure.

RESULTS

Implant removal was associated with a complication rate of 47%. The major problems encountered were difficulty in removing the locked screws and the implant itself. A total of ten cold welded screws were found in eight cases. Removal was facilitated by high speed metal cutting burrs and screw removal sets in all but one case, where a decision was made to leave the plate in situ.

CONCLUSIONS

The majority of studies investigating implant removal and problems encountered in doing so report a relatively high complication rate. With the advent of locking plates and their growing popularity, difficulties are now being seen intraoperatively when removing them. There is a paucity of data, however, specifically directed at locking plate removal. We recommend that surgeons should be aware of the potential complications while removing locked plates. Fluoroscopic control and all available extra equipment (mainly metal cutting burrs and screw removal sets) should be available in theatre.

[Refracture of long bones after implant removal. An avoidable complication?]

Refractures of long bones after implant removal are a rare but serious complication, which in most cases make a reoperation necessary. We analysed our own cases and reviewed the scarce literature on this subject. As a result we found that it is possible to reduce this complication by performing thorough preoperative preparation, observing an adequate interim time between initial osteosynthesis and hardware removal, cautiously exposing the weakened bone to force for a certain time period after implant removal and taking the character of the fracture healing into consideration. It is not possible to entirely eradicate this complication because a lot of patients demand the implant removal even though it is known that demineralisation and residual screw holes both induce a reduction of energy-absorbing capacity and therefore predispose the patient to refracture. In some cases the surgeon should recommend that the implants remain in situ.

Implant removal of osteosynthesis: the Dutch practice. Results of a survey

Background

The aim of this survey study was to evaluate the current opinion and practice of trauma and orthopaedic surgeons in the Netherlands in the removal of implants after fracture healing.

Methods

A web-based questionnaire consisting of 44 items was sent to all active members of the Dutch Trauma Society and Dutch Orthopaedic Trauma Society to determine their habits and opinions about implant removal.

Results

Though implant removal is not routinely done in the Netherlands, 89% of the Dutch surgeons agreed that implant removal is a good option in case of pain or functional deficits. Also infection of the implant or bone is one of the main reasons for removing the implant (> 90%), while making money was a motivation for only 1% of the respondents. In case of younger patients (< 40 years of age) only 34% of the surgeons agreed that metal implants should always be removed in this category. Orthopaedic surgeons are more conservative and differ in their opinion about this subject compared to general trauma surgeons (p = 0.002). Though the far majority removes elastic nails in children (95%).

Most of the participants (56%) did not agree that leaving implants in is associated with an increased risk of fractures, infections, allergy or malignancy. Yet in case of the risk of fractures, residents all agreed to this statement (100%) whereas staff specialists disagreed for 71% (p < 0.001). According to 62% of the surgeons titanium plates are more difficult to remove than stainless steel, but 47% did not consider them safer to leave in situ compared to stainless steel. The most mentioned postoperative complications were wound infection (37%), unpleasant scarring (24%) and postoperative hemorraghe (19%).

Conclusion

This survey indicates that there is no general opinion about implant removal after fracture healing with a lack of policy guidelines in the Netherlands. In case of symptomatic patients a majority of the surgeons removes the implant, but this is not standard practice for every surgeon.

The benefits of implant removal from the foot and ankle

BACKGROUND

Following successful orthopaedic surgical procedures, implant removal is generally not necessary or recommended. However, patients with pain related to implants may benefit from this elective procedure. The foot and ankle may be more symptomatic from retained implants because of weight-bearing activities, shoe wear, and limited soft-tissue cushioning. In such cases, implant removal may provide good and reliable relief of symptoms.

METHODS

A prospective study of sixty-nine patients who underwent elective removal of symptomatic implants from the foot and ankle was undertaken to evaluate the patients' pain experience. The short-form McGill pain questionnaire was administered preoperatively and six weeks postoperatively. Postoperatively, patients were also asked whether they would repeat the procedure and whether they were satisfied with the results.

RESULTS

Patients reported significantly less pain following the procedure, with the average rating of pain on the visual analog scale (VAS) decreasing from 3.06 to 0.88 and the average rating of present pain intensity decreasing from 2.03 to 0.58 (p < 0.05 for both). Sixty-five percent of the patients reported no pain on either measure at six weeks postoperatively. Preoperative pain was correlated with postoperative pain (r = 0.24 and p < 0.05 for VAS, and r = 0.16 and p > 0.05 for present pain intensity).With the small sample size, preoperative and postoperative pain did not show a significant difference on the basis of implant location or patient age or sex. Ninety-four percent of patients said they would repeat the procedure under the same circumstances, and 91% of patients were satisfied with the results.

CONCLUSIONS

Following successful orthopaedic surgical procedures, removal of implants causing symptoms can result in pain relief and a high rate of patient satisfaction.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Impact Response and Simulation of Damaged Ulna With Internal Fixation

The objectives of this work were to explore a methodology that combines static and dynamic finite element (FE) analysis, linear elastic fracture mechanics (LEFM) and experimental methods to investigate a worst-case scenario in which a previously damaged bone plate system is subjected to an impact load. Cadaver ulnas with and without midshaft dynamic compression plates are subjected to a static three-point bend test and loaded such that subcritical crack growth occurs as predicted by a hybrid method that couples LEFM and static FE. The plated and unplated bones are then unloaded and subsequently subjected to a midshaft transverse impact test. A dynamic strain-based FE model is also developed to model the midshaft transverse impact test. The average value of the impact energy required for failure was observed to be 10.53% greater for the plated set. There appears to be a trade-off between impact damage and impact resistance when ulnas are supported by fixation devices. Predictions from the dynamic FE model are shown to corroborate inferences from the experimental approach.

Metalwork removal in elective foot and ankle practice: does it make any difference to the patient?

BACKGROUND

Increasing use of metalwork in foot and ankle surgery has led to an increasing number of subsequent surgeries for metalwork removal. The aim of the current study was to determine whether removing metalwork from foot and ankle makes any difference to the patients in terms of pain, function or shoe wear related outcomes.

METHODS

27 consecutive patients were identified from a single surgeon database that had undergone metalwork removal over a four year period and sent out a validated Visual Analogue Scale-Foot and Ankle questionnaire. Additional demographic and radiographic data were collected.

RESULTS

24 patients returned completed questionnaires. Mean interval between index procedure and metalwork removal was 18months. Overall for the whole group, only moderate satisfaction was noted after metalwork removal with mean VAS-FA scores of 60.39. The mean VAS-FA scores and the pain, function and other complaints sub-scores were significantly better in patients who had metalwork removal after 1st ray surgery (p=0.07 for total VAS-FA score and p=0.006, p=0.005, and p=0.032 for pain, function and other complaints sub-scores respectively).

CONCLUSION

We can recommend removal of metalwork in symptomatic patients after 1st ray surgeries but other foot and ankle surgeries require further investigation.

Pregnancy outcomes after pelvic ring injury

OBJECTIVES

Previous studies reported negative effects of pelvic trauma on genitourinary and reproductive function with frequent cesarean delivery. Risk factors for cesarean delivery have not been well defined. The purpose of this project was to evaluate outcomes of pregnancy after pelvic ring injury. We hypothesized that cesarean delivery would be more frequent after pelvic fracture with potential causes including patient and physician preference, malunion, and retained hardware.

DESIGN

Retrospective review with prospective collection of obstetric information.

SETTING

Level I trauma center.

PATIENTS/PARTICIPANTS

Thirty-one women, 16 to 40 years old, with pregnancy after healed pelvic fracture.

INTERVENTION

Orthopaedic Trauma Association (OTA) classification included 10 B-type and 21 C-type fractures, 17 (55%) of which were treated surgically.

MAIN OUTCOME MEASUREMENTS

Obstetric questionnaires were obtained for 54 pregnancies after a mean 72 months follow-up.

RESULTS

Sixteen women had 25 vaginal deliveries; 28% after surgical treatment for their pelvic fracture with retained anterior (16%) and/or posterior (16%) hardware, including transsymphyseal plating in three patients (12%). Thirteen women had 26 cesarean deliveries, 46% after surgical treatment for their pelvis. The new cesarean delivery rate was 44% versus 17% preinjury (P = 0.02). Two had cesarean deliveries as repeat procedures after preinjury cesarean delivery. Four had cesarean deliveries as a result of medical complications (pre-eclampsia, n = 2; breech, n = 1; labor arrest, n = 2). Seven women (54%) reported 12 cesarean deliveries (46%) resulting from pelvic fracture; three elected cesarean delivery despite their physician offering a trial of labor, whereas four were advised by their obstetrician. Cesarean delivery was not related to age, fracture pattern, treatment type, or residual pelvic displacement. A trend for cesarean delivery related to retained hardware was observed (P = 0.06).

CONCLUSIONS

Uncomplicated pregnancies and deliveries are possible after pelvic fracture. The new cesarean delivery rate among these women is significantly increased with over half related to patient and obstetrical preferences. Fracture pattern, minor malalignment, and retained hardware are not absolute indications for cesarean delivery. Neither surgical care of the pelvis or retained fixation precludes successful vaginal delivery. Development of guidelines and objective indications for trial of normal labor after pelvic fracture is needed.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Management of the contralateral hip in patients with unilateral slipped upper femoral epiphysis: to fix or not to fix--consequences of two strategies

In the majority of patients with slipped upper femoral epiphysis only one hip is involved at primary diagnosis. However, the contralateral hip often becomes involved over time. There are no reliable factors predicting a contralateral slip. Whether or not the contralateral hip should undergo prophylactic fixation is a matter of controversy. We present a number of essential points that have to be considered both when choosing to fix the contralateral hip prophylactically as well as when refraining from surgery and instead following the patients with repeat radiographs.

Femoral neck fracture following hardware removal

It is uncommon for femoral neck fractures to occur after proximal femoral hardware removal because age, osteoporosis, and technical error are often noted as the causes for this type of fracture. However, excessive alcohol consumption and failure to comply with protected weight bearing for 6 weeks increases the risk of femoral neck fractures.This article describes a case of a 57-year-old man with a high-energy ipsilateral inter-trochanteric hip fracture, comminuted distal third femoral shaft fracture, and displaced lateral tibial plateau fracture. Cephalomedullary fixation was used to fix the ipsilateral femur fractures after medical stabilization and evaluation of the patient. The patient healed clinically and radiographically at 6 months. Despite conservative treatment for painful proximal hardware, elective hip screw removal was performed 22.5 months after injury. Seven weeks later, he sustained a nontraumatic femoral neck fracture.In this case, it is unlikely that the femoral neck fracture occurred as a result of hardware removal. We assumed that, in addition to the patient's alcohol abuse and tobacco use, stress fractures may have attributed to the femoral neck fracture. We recommend using a shorter hip screw to minimize hardware prominence or possibly off-label use of an injectable bone filler, such as calcium phosphate cement.

Total hip arthroplasty in the ankylosed hip

Altered biomechanics secondary to hip ankylosis often result in degeneration of the lumbar spine, ipsilateral knee, and contralateral hip and knee. Symptoms in these joints may be reduced with conversion total hip arthroplasty (THA) of the ankylosed hip. THA in the ankylosed hip is a technically challenging procedure, and the overall clinical outcome is generally less satisfactory than routine THA performed for osteoarthritis and other etiologies. Functional integrity of the hip abductor muscles is the most important predictor of walking ability following conversion THA. Many patients experience persistent limp, and it can take up to 2 years to fully assess final functional outcome. Risk factors cited for increased risk of failed THA include prior surgical ankylosis and age <50 years at the time of conversion THA.

Removal of locking plates: new implant, new challenges and new solutions

Removal of locking plates in many ways poses novel challenges compared to conventional plates. None of the techniques described for the removal of locking plates are adequate for all situations. We report our experience of 27 patients from whom a total of 33 locking plates were removed. We also describe a novel technique for the removal of locking plates which in our experience could be used in most of these patients because it is appropriate for all situations and, from a technical point of view, is easy to use. Our new technique consists of removing the problematic locking screw by cutting the plate on both sides of the screw hole and using the screw head-plate hole unit for removal. We analyzed all these patients for the location of the plate, number of locking screws, time of implant removal since the initial surgery, reason for removal of the plate, nature of the difficulties encountered during surgery, and any perioperative complications. A total of 43 (17.34%) screws were difficult to remove. Twenty screws were found to be stripped, 15 were jammed and 8 were broken. Fourteen of the 20 stripped screws and all 15 jammed screws were removed using our technique. We found this technique of locking plate removal to be very versatile and useful in most of the cases in which removal was difficult. At the same time, it also causes less damage to the bone compared to other techniques.

Complications of syndesmotic screw removal

BACKGROUND

Currently, the metallic syndesmotic screw is the gold standard in the treatment of syndesmotic disruption. Whether or not this screw needs to be removed remains debatable. The aim of the current study was to determine the complications which occur following routine removal of the syndesmotic screw following operative treatment of unstable ankle fractures.

METHODS

This was a retrospective study with consecutive cases in a Level-2 Trauma center. All patients with routine removal of a syndesmotic screw, following the treatment of an unstable ankle fracture, between January 1, 2004 and November 30, 2010 were included. Complications recorded were: 1) minor or major wound infection following removal of the syndesmotic screw, 2) recurrent syndesmotic diastasis, and 3) unnecessary removal of a broken screw, not recognized during preoperative planning prior to surgery.

RESULTS

A total of 76 patients were included. A wound infection occurred in 9.2% (N = 7) of which 2.6% (N = 2) were deep infections requiring reoperation. Recurrent syndesmotic diastasis was found in 6.6% (N = 5) of patients, and in 6.6% (N = 5) screws were broken at the time of implant removal. In the group with recurrent diastasis the screws were removed significantly earlier compared with the group without recurrent diastasis (Mann-Whitney U-test; p = 0.011) and the group with screw breakage had their screws significantly longer in place compared with the group without breakage (p = 0.038).

CONCLUSION

A total of 22.4% complications occurred upon routine removal of the syndesmotic screw. Removal might therefore be considered only in selected cases with complaints, after a minimum of eight to twelve weeks and using antibiotic prophylaxis during removal.

Should extramedullary fixations for hip fractures be removed after bone union?

BACKGROUND

Osteosynthesis implants, which remain in the patient after fracture union to save additional surgery, may affect the strain distribution within the bone. A reduction of strain within the bone is known to result in localized bone loss ("stress shielding") and increased fracture risk. The purpose of this study was to examine whether extramedullary fixations for femoral neck fractures have to be removed after fracture union to prevent reductions in cortex strains.

METHODS

In a biomechanical experiment, six pairs of human cadaver femora (mean age 56 years, range 48 to 64) were supplied with five strain gauges per bone. The bones were equally supplied with a compression hip screw or a femoral neck plate. Before surgery, after surgery and after removal of the implants, axial compression tests were conducted to measure surface strains during loading.

FINDINGS

The compression hip screw reduced the amount of strain at the superior neck by 88% (P=0.015) and at the lesser trochanter by 51% (P=0.038). The femoral neck plate reduced the amount of strain at the superior neck by 89% (P=0.001), and increased the amount of strain at the inferior neck by 58% (P=0.02) and at the lesser trochanter by 63% (P=0.005). After implant removal, there was no significant difference in strain compared to pre-fracture levels, except for the compression hip screw with 21% less strain (P=0.047) at the superior neck.

INTERPRETATION

Removal of osteosynthesis implants after bone union reverts bone strains to pre-fracture levels, and might prevent further bone loss induced by stress shielding.

Implant removal associated complications in children with limb fractures due to trauma

Purpose

The purpose of this study was to analyze the number and type of complications that occurred after fracture implant removal and to investigate whether implant removal should be performed routinely in children.

Methods

In a retrospective study, patient records were used for the analyses of patient characteristics, surgery reports, and complications. Children under the age of 16 years with a limb fracture due to trauma, treated with either Kirschner wires (K-wires), elastic stable intramedullary nails (ESIN), or screw fixation between 2000 and 2007, were included. Exclusion criteria were as follows: refracture, pathological fracture, fracture of the hands and feet, or polytrauma patients (Injury Severity Score [ISS] > 15).

Results

Three-hundred and nine fractures were analyzed. All K-wires (173) and ESIN (96) were removed as per standard procedure, resulting in 17/173 and 7/96 complications after removal, respectively. In 19/40 patients with screw fixation treatments, it was decided to remove the material after fracture consolidation, resulting in 4/19 complications. The decision in 21 treatments to leave the screw in situ led to four complications. No significant difference in complication rates could be found for the three groups after removal surgery (17/173, 7/96, and 4/19) or between hardware removal (4/19) and retention (4/21) in the case of screw fixation.

Conclusions

The removal of K-wires, ESIN, and screws is considered to be a safe procedure in children and is, by definition, indicated for K-wires and ESIN after fracture healing.

Repeated floating elbow injury after high-energy trauma

The floating elbow is an uncommon injury occurring both in children and in adults. Two reports of rare variants of floating elbow injury have been published, but to the best of our knowledge, no recurrence of this injury has been described. We present a complex pattern of floating injury, occurring in the same limb 3 years after a floating elbow lesion, which included supracondylar fracture of the humerus and associated ipsilateral midshaft fracture of forearm bones. Satisfactory outcomes were finally obtained. This clinical case illustrates the importance of carefully assessing floating elbow injuries when they occur to optimize the surgical strategies and the adequate timing of the treatment. A comprehensive literature review of the floating elbow injuries is here reported.

Modified tension band technique for patella fractures

The use of tension band wire technique for patella fractures fixation is a well-established technique. However, the standard technique, which involves using two Kirschner wires through the patella, can cause problems with prominent hardware, and difficulty capturing the change to figure of eight wire. Here we describe a modified technique using four Kirschner wires, which allows each wire to be bent, and well-impacted in order to avoid these problems. The basic surgical technique, and our case series are reviewed.

Removal of deep extremity implants in children

We have reviewed our experience of the removal of deep extremity orthopaedic implants in children to establish the nature, rate and risk of complications associated with this procedure. A retrospective review was performed of 801 children who had 1223 implants inserted and subsequently removed over a period of 17 years. Bivariate analysis of possible predictors including clinical factors, complications associated with implant insertion and indications for removal and the complications encountered at removal was performed. A logistical regression model was then constructed using those predictors which were significantly associated with surgical complications from the bivariate analyses. Odds ratios estimated in the logistical regression models were converted to risk ratios.

The overall rate of complications after removal of the implant was 12.5% (100 complications in 801 patients), with 48 (6.0%) major and 52 (6.5%) minor. Children with a complication after insertion of the initial implant or with a non-elective indication for removal, a neuromuscular disease associated with a seizure disorder or a neuromuscular disease in those unable to walk, had a significantly greater chance of having a major complication after removal of the implant. Children with all four of these predictors were 14.6 times more likely to have a major complication.

Technical problems and complications in the removal of the less invasive stabilization system

OBJECTIVES

This study was designed to evaluate the frequency of intraoperative problems and complications involved with Less Invasive Stabilization System (LISS) plate removal.

DESIGN

Retrospective study.

SETTING

Single academic level I trauma center.

METHODS

Medical records were reviewed for demographics, surgical technique, plate length, number and position of screws, time from internal fixation to plate removal, reason for removal, operating time for removal, and perioperative complications. Pre- and post-op radiographs were also reviewed to confirm plate and screw positions. The independent factors including age, sex, plate site, plate screws placed/available holes, union status, and time from internal fixation to removal were compared between patients in whom screw removal was complicated to those in whom screw removal proceeded without difficulty. Mann-Whitney and Fisher Exact tests were calculated with the level of significance at P < 0.05.

RESULTS

There were 33 patients (24 men and 9 women) that underwent LISS plate removal from 36 extremities (15 tibias and 21 femurs). The average time from internal fixation to removal was 13.2 months. The plates removed were 13-hole plates (16 cases), 9-hole plates (18 cases), and 5-hole plates (2 cases), which included a total of 349 screws. The specific reasons for plate removal were symptomatic implants after bone union (21 cases), nonunion requiring additional fixation (12 cases), early loss of fixation (2 cases), and a peri-implant fracture after bone union (1 case). The average operating time for plate removal was 71.3 minutes (range, 28-180 minutes). Five cases required more than 120 minutes. Difficulty with screw removal was encountered in 37 screws (10.6%) from 14 cases (38.9%). Two plates and 11 screw heads required cutting using a carbide or diamond tipped burr. Six cases required tearing the plate off bone by levering with a total of 10 screws still attached. Five screws were cut using a large bolt cutter. The other screws were stripped and removed with a stripped screw removal tap. Two patients developed a postoperative superficial wound infection that required treatment with oral antibiotics. One patient had a postoperative peroneal nerve palsy that recovered spontaneously. There were no statistical differences in predictors for patients with screw removal difficulty.

CONCLUSIONS

Difficulty with removal due to cold welding or screw head stripping is common in locking LISS plate screws. LISS plate removal can often require prolonged operating time and the use of specialized removal tools. Surgeons should anticipate the possibility of difficulties when removing these implants and be appropriately prepared.

Implant removal after submuscular plating for pediatric femur fractures

BACKGROUND

Submuscular plating for pediatric femur fracture has become more commonplace for treatment of length unstable fractures. These plates act as an internal fixator and rely on minimally invasive insertion techniques and long plate lengths to achieve the goal of stable fixation and local biologic fracture preservation. Plate removal in children after submuscular plating has not been reported in the literature.

METHODS

We reviewed the records of 22 patients at our institution who were treated with a submuscular plate, which was eventually removed after fracture healing. A review of the radiographs and charts was performed to determine any unique problems or complications that may arise during the removal of these plates given their long lengths and minimally invasive insertion.

RESULTS

In our series, 7 patients required a more extensive procedure to remove the plate than was required during plate insertion. These patients all required an open procedure at the leading edge of the plate to chisel overgrown bone away from the plate for removal. The timing of removal in our series was not related to difficulties during plate removal, rather it was the presence of bony overgrowth at the plates leading edge. This overgrowth was seen early on radiographically during the healing process in all patients who required increased operative exposure.

CONCLUSIONS

The timing of plate removal after submuscular plating is not critical when trying to determine the potential complications at plate removal. The decisive factor related to difficulties with plate removal is leading plate edge overgrowth. Patients with this bone overgrowth at the leading edge of the plate need to be counseled regarding the need for an increased operative exposure during plate removal.

LEVEL OF EVIDENCE

Case series, level 4.

Clinical application of locked plating system in children. An orthopaedic view

In recent years, the locked plating system has gained favour in the treatment of certain fractures in adults; however, there is not much information regarding its use in children. We think there could be some advantages and applications such as: an alternative to external fixation, the bridge plating technique, unicortical screws, removal of hardware, metadiaphyseal fractures, periarticular fractures, poor quality bone, and allograft fixation. However, there are some disadvantages to keep in mind and the final decision for using it should be based on the osteosynthesis method principle the surgeon would like to apply. In this review article we discuss the up-to-date possible clinical applications and issues of this system.

Outcomes analysis after routine removal of implants in healthy pediatric patients

Routine removal of nonspinal, orthopedic implants from pediatric patients is a debated practice. The purpose of this study was to compare preremoval and postremoval outcome measures in children. Twenty-five patients, mean age 11.6 years, completed a pain scale and the Pediatric Outcomes Data Collection Instrument (PODCI). Many patients scored in the normal range of the PODCI before and after removal. Higher postoperative PODCI scores were found in patients without preoperative pain, and in patients with upper extremity versus lower extremity implants. In summary, routine removal of implants in children was carried out without complications and with some functional benefits.

Biodegradable Polymers in Bone Tissue Engineering

The use of degradable polymers in medicine largely started around the mid 20^th century with their initial use as in vivo resorbing sutures. Thorough knowledge on this topic as been gained since then and the potential applications for these polymers were, and still are, rapidly expanding. After improving the properties of lactic acid-based polymers, these were no longer studied only from a scientific point of view, but also for their use in bone surgery in the 1990s. Unfortunately, after implanting these polymers, different foreign body reactions ranging from the presence of white blood cells to sterile sinuses with resorption of the original tissue were observed. This led to the misconception that degradable polymers would, in all cases, lead to inflammation and/or osteolysis at the implantation site. Nowadays, we have accumulated substantial knowledge on the issue of biocompatibility of biodegradable polymers and are able to tailor these polymers for specific applications and thereby strongly reduce the occurrence of adverse tissue reactions. However, the major issue of biofunctionality, when mechanical adaptation is taken into account, has hitherto been largely unrecognized. A thorough understanding of how to improve the biofunctionality, comprising biomechanical stability, but also visualization and sterilization of the material, together with the avoidance of fibrotic tissue formation and foreign body reactions, may greatly enhance the applicability and safety of degradable polymers in a wide area of tissue engineering applications. This review will address our current understanding of these biofunctionality factors, and will subsequently discuss the pitfalls remaining and potential solutions to solve these problems.

Biomechanical evaluation of bioabsorbable versus metallic screws for posterior cruciate ligament inlay graft fixation: a comparative study

BACKGROUND

Although a tibial inlay technique for posterior cruciate ligament reconstruction is advantageous, metallic screw fixation of the bone block is required. This may pose problems for future surgery (eg, osteotomies, total knee replacement).

HYPOTHESIS

There is no significant difference in the biomechanical integrity of bone block fixation using stainless steel versus bioabsorbable screw fixation of the tibial inlay graft in posterior cruciate ligament reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fourteen human cadaveric knees were randomized to receive either stainless steel or bioabsorbable screw fixation of a bone-patellar tendon-bone graft. Cyclic tensile testing of each construct was performed, followed by a load-to-failure test. Digital video digitization was used to optically determine tendon graft deformation.

RESULTS

Cyclic creep deformation showed no significant difference between the 2 groups (P = .8). The failure load (stainless steel, 461 +/- 231 N; bioabsorbable, 638 +/- 492 N; P = .7) and linear stiffness (stainless steel, 116 +/- 22 N/mm, bioabsorbable, 106 +/- 44 N/mm; P = .6) also showed no significant difference between the 2 groups. Optically measured graft deformation was not significant for distal (P = .7) and midsubstance (P = .8) regions, while proximal deformation was significantly higher for bioabsorbable fixation (P = .02). All samples failed at the tibial insertion site with the tibial bone block fracturing at the screws.

CONCLUSION

Bioabsorbable screw fixation using a tibial inlay technique does not compromise the strength and stiffness characteristics afforded by metallic fixation. From a biomechanical perspective, bioabsorbable screws are a viable alternative to metal in the context of tibial inlay reconstruction.

CLINICAL RELEVANCE

Use of bioabsorbable fixation can potentially eliminate future hardware problems after posterior cruciate ligament reconstruction using a tibial inlay technique.

Evidence-based analysis of removal of orthopaedic implants in the pediatric population

BACKGROUND

Requested project of the Pediatric Orthopaedic Society of North America Evidenced-Based Medicine Committee.

METHODS

The English literature was systematically reviewed for scientific evidence supporting or disputing the common practice of elective removal of implants in children.

RESULTS

Several case series reported implant removal, but none contained a control group with retained implants. No articles reported long-term outcomes of retained implants in large numbers. Several small series describe complications associated with retained implants without evidence of causation. The existing literature was not amenable to a meta-analysis. By compiling data from the literature, it is possible to calculate a complication rate of 10% for implant removal surgery. The complication rate for removal of implants placed for slipped capital femoral epiphysis is 34%. Articles regarding postmarket implant surveillance and basic science were also reviewed.

CONCLUSIONS

There is no evidence in the current literature to support or refute the practice of routine implant removal in children.

Effect of surface topography on removal of cortical bone screws in a novel sheep model

Difficulty in removing implants used in trauma patients can be a complication, and increased bone-implant adhesion likely is a major contributing factor. In vitro studies have shown that surface morphology of implant materials has the ability to influence cellular responses, with polished surfaces decreasing the potential for mineralization. This study examined the effect of polishing commercially pure titanium (cpTi) and the titanium alloy TAN on the removal torque and percentage bone-implant contact in cortical and cancellous bone of sheep. Polishing had a significant effect on both removal torque and percentage bone-implant contact, with the polished implants demonstrating a lower removal torque in both cortical and cancellous bone. Polished cpTi and stainless steel were similar in terms of surface roughness and removal torque. However, polished TAN, which was not as smooth as polished cpTi, did not show the same low level for reducing removal torque. Improved polishing of TAN should reduce the removal torque further. The results of the study show that polishing is promising in improving the ease of implant removal after fracture fixation and repair.

Fracture incidence following plate removal in Legg-Calvé-Perthes disease: a 32-year study

PURPOSE

The decision of whether or not to remove pediatric metallic implants remains a controversial issue. Many factors have been cited both in favor and against routine removal of metallic implants. The purpose of this study was to determine the fracture rate following the routine removal of hardware from patients with Legg-Calvé-Perthes (LCP) disease treated by proximal femoral varus osteotomy (PFVO) and to determine if there is an optimal time to remove hardware in this population.

METHODS

We performed a retrospective chart review of children who had PFVO with subsequent hardware removal from March 1973 to May 2005 performed by a single surgeon. A total of 196 hips in 184 patients were included. Data was analyzed using logistic regression. Inverse prediction was also used to obtain estimates of the time needed to produce probabilities of no fracture.

RESULTS

Ten out of the 196 hips included (5.1%) sustained a fracture after plate removal. The time from osteotomy to plate removal averaged 10.4 months in the nonfracture group and 4.8 months in the fracture group. This was statistically significant (P < 0.0001). Using the logistic regression model, the predicted time to plate removal corresponding to a 95% probability of no fracture was between 5.1 and 8.4 months.

CONCLUSIONS

Plate removal remains a reasonable choice but questions remain as to the timing of removal. These data suggest that patients may benefit from extending the time to hardware removal beyond radiographic union to at least six months or more after the osteotomy.

The use of locked plating in skeletally immature patients

The philosophy and techniques for the management of fractures in the pediatric patient have changed over the past several decades. The immature skeleton has unique properties, and injuries in children have different characteristics, management options, and complications than do similar injuries in adults. The basic surgical techniques used in the management of pediatric fractures include closed reduction and casting, closed or open reduction with internal fixation, and external fixation. The concept of bridging plate osteosynthesis has evolved based on scientific insight into bone biology and the importance of blood supply to bone. The use of locked plating is gaining favor in the treatment of certain fractures in adults. However, the role for this technique in the skeletally immature patient has not been described.

Do orthopaedic surgeons need a policy on the removal of metalwork? A descriptive national survey of practicing surgeons in the United Kingdom

INTRODUCTION

Routine metalwork removal, in asymptomatic patients, remains a controversial issue. Current literature emphasises the potential hazards of implant removal and the financial implications encountered from these procedures. However, there is little literature guidance and no published research on current practice.

AIM

To estimate the current state of practice of orthopaedic surgeons in the United Kingdom regarding implant removal in asymptomatic patients.

METHODS

An analysis, by two independent observers, was performed on the postal questionnaire replies of 36% (500 out of 1390), randomly selected UK orthopaedic consultants.

RESULTS

Four hundred and seven (81%) replies were received. A total of 345 (69%) were found to be suitable for analysis. The most significant results of our study (I) 92% of orthopaedic surgeons stated that they do not routinely remove metalwork in asymptomatic skeletally mature patients; (II) 60% of trauma surgeons stated that they do routinely remove metalwork in patients aged 16 years and under; (III) 87% of the practicing surgeons indicated that they believe it is reasonable to leave metalwork in for 10 years or more; (IV) only 7% of practicing trauma surgeons who replied to this questionnaire have departmental or unit policy.

CONCLUSION

Our results demonstrate that most practicing trauma surgeons do comply with the evidence presented in the little literature available. However, we do believe that a general policy for metalwork removal is essential. Such a policy should include guidelines specific to age groups and level of surgeon who should be performing the removal procedure. Such a document would require further validated studies but would eventually serve to steer surgeons in achieving best practice.

Removal of broken hardware

Despite advances in metallurgy, fatigue failure of hardware is common when a fracture fails to heal. Revision procedures can be difficult, usually requiring removal of intact or broken hardware. Several different methods may need to be attempted to successfully remove intact or broken hardware. Broken intramedullary nail cross-locking screws may be advanced out by impacting with a Steinmann pin. Broken open-section (Küntscher type) intramedullary nails may be removed using a hook. Closed-section cannulated intramedullary nails require additional techniques, such as the use of guidewires or commercially available extraction tools. Removal of broken solid nails requires use of a commercial ratchet grip extractor or a bone window to directly impact the broken segment. Screw extractors, trephines, and extraction bolts are useful for removing stripped or broken screws. Cold-welded screws and plates can complicate removal of locked implants and require the use of carbide drills or high-speed metal cutting tools. Hardware removal can be a time-consuming process, and no single technique is uniformly successful.

Complications of anterior cruciate ligament reconstruction with bone-patellar tendon-bone constructs: care and prevention

Rupture of the anterior cruciate ligament is a common injury. Correct diagnosis and patient selection, along with proper surgical technique, with careful attention to anatomic graft placement, followed by attention to proper rehabilitation, leads to predictably good to excellent results. This article reviews the recognition and avoidance of complications associated with bone-patellar tendon-bone constructs of anterior cruciate ligament reconstruction.

Congruent elbow plate fixation of olecranon fractures

OBJECTIVES

We hypothesize that clinical results and patient outcomes following treatment of olecranon fractures with a congruent elbow plating system will be comparable to other available plating systems. Our results will be compared to previously published reports.

DESIGN

Retrospective study.

SETTING

Level 1 academic referral center.

PATIENTS/PARTICIPANTS

The trauma registry was reviewed to identify all olecranon fractures treated with open reduction and internal fixation between January 2001 and December 2004 using the Mayo Congruent Elbow Plate system. Thirty-two patients were identified. Postoperative range of motion was initiated within 2 weeks postoperatively. Mean time to follow-up was 2.2 years (0.7-5.1). All patients had follow-up radiographs. Outcome scores were available on 24 of the 32 patients.

INTERVENTION

Medical records and radiographs of all patients were reviewed.

MAIN OUTCOME MEASUREMENTS

Objective measures included radiographic healing, postoperative range of motion, and complications. Subjective functional results included Mayo Elbow Performance (MEP) score; Disability of the Arm, Shoulder, and Hand (DASH) score; and patient satisfaction.

RESULTS

Of the 32 fractures, 30 went on to union. Three patients had symptomatic hardware that was removed. There was 1 infection and 1 failure of fixation also requiring hardware removal. Average arc of motion was 120 degrees. Subjective follow-up was available in 75% of patients. Mean DASH was 32. Mean MEPS was 89, with 92% good or excellent results.

CONCLUSIONS

Congruent anatomic plating is a safe, effective option for the treatment of olecranon fractures with a low rate of hardware removal and stability with early motion.

Calcium phosphate cement augmentation of the femoral neck defect created after dynamic hip screw removal

OBJECTIVE

To determine the effect of reinforced calcium phosphate cement augmentation of the femoral neck defect created after dynamic hip screw removal in a cadaveric model.

METHODS

The lag screws of dynamic hip screw implants were inserted and subsequently removed in 8 matched pairs of cadaveric, osteoporotic femurs to create a femoral neck defect. One of each pair had the defect augmented with osteoconductive calcium phosphate cement reinforced with poly(lactide-coglycolide) fibers (Norian Reinforced, Synthes, West Chester, PA), and the other defect was not augmented. Each specimen was first cyclically loaded with 750 N vertical loads applied for 1000 cycles to simulate early weightbearing, and then loaded to failure.

RESULTS

Calcium phosphate cement augmentation of the lag screw defect significantly increased the mean femoral neck failure strength (4819 N) compared to specimens in which the defect was left untreated (3995 N) (P < 0.004). The mechanism of failure for each specimen was a fracture through the femoral neck. Regression analysis demonstrated that load to failure was directly related to the bone mineral density at Ward's triangle, and the impact of cement augmentation on failure strength was greatest for specimens with the lowest bone mineral density (correlation coefficient: -0.82, P < 0.0001).

CONCLUSION

This study demonstrates that augmentation of the bony defect created by dynamic hip screw removal with reinforced calcium phosphate cement significantly improved the failure strength of the bone. Cement augmentation after hardware removal may decrease the risk of refracture and allow early weightbearing, especially in elderly patients with osteoporotic bone.