Does Computer-assisted Surgery Improve Lag Screw Placement During Cephalomedullary Nailing of Intertrochanteric Hip Fractures?

BACKGROUND: Computer-assisted surgery (CAS) techniques have been shown to improve implant placement and reduce the radiation time during cephalomedullary nailing in cadaveric and pilot clinical studies of intertrochanteric hip fractures. However, clinical comparisons of CAS and conventional techniques are lacking. It is unclear whether CAS offers clear advantages in terms of radiation time, operative time, and accuracy of lag-screw placement in patients undergoing surgery for intertrochanteric hip fractures and whether any potential difference in accuracy is associated with a change in the risk of lag-screw cut-out postoperatively. QUESTIONS/PURPOSES: In patients undergoing cephalomedullary nailing for intertrochanteric hip fractures compared with the conventional technique, we asked: (1) Is the CAS technique associated with a decrease in tip-apex distance (TAD), with less variation and fewer outliers at the standard (25 mm) and lower (15 mm) TAD thresholds? (2) Is the CAS technique associated with a decrease in radiation and operative time? (3) If the CAS technique results in a decrease in TAD, is this decrease associated with a decrease in lag screw cut-out postoperatively? METHODS: Between Oct 2007 and June 2015, 964 stable and unstable intertrochanteric hip fractures were treated surgically at our institution. Of these, 23% (225 of 964) were isolated, acute intertrochanteric hip fractures managed by a single surgeon. Ninety-five percent (213 of 225) of hip fractures were surgically treated with the same cephalomedullary nail based on the general indications of displaced fractures, poor bone quality, and medical complexity. This same surgeon used a sliding hip screw device in the remaining 5% (12 of 225) of hip fractures for the treatment of nondisplaced and minimally displaced fractures in younger patients with fewer medical comorbidities and good bone quality. Between October 2007 and August 2011, all procedures were performed with conventional lag screw placement (n = 110), and between September 2011 and June 2015, all procedures were performed with CAS (n = 103) for lag screw placement. Postoperative radiographs were missing or unavailable for TAD analysis for 3% (3 of 110) of the conventional technique group and 6% (6 of 103) of the CAS group, so these patients were excluded. The remaining 97% (107 of 110) of conventional procedures and 94% (97 of 103) of CAS procedures were included in the TAD, radiation time, and operative time analysis. For the evaluation of cut-out postoperatively, 24% (26 of 107) of conventional patients and 25% (24 of 97) of CAS patients were excluded due to mortality and/or loss to follow-up at a minimum of 1 year. The remaining 76% (81 of 107) of conventional patients and 75% (73 of 97) of CAS patients were included in the cut-out analysis. A retrospective chart review was performed to obtain the data and then compare TAD, radiation time, operative time, and cut-out between the two cohorts. RESULTS: The median TAD for the CAS procedures was lower than the median TAD for the conventional procedures (median 13 mm versus median 16 mm, median difference 3 mm; p < 0.001 power for difference = 85%). In addition, the TAD variation was also less for the CAS procedures compared with the conventional procedures (interquartile range [IQR] 4 mm versus IQR 9 mm, IQR difference 5 mm; p < 0.001, power for difference = 98%). A TAD greater than 25 mm was found in 1% (1 of 97) of the CAS procedures and 12% (13 of 107) of the conventional procedures. A difference between the proportions could be detected indicating a lesser chance of a TAD > 25 mm in the CAS cohort (odds ratio = 0.075 [95% confidence interval 0.010 to 0.587]; p = 0.002, power for difference 90%). A TAD > 15 mm was found in 23% (22 of 97) of the CAS procedures and 56% (60 of 107) of the conventional procedures, also indicating a lesser chance of a TAD > 15 mm in the CAS cohort (OR = 0.230 [95% CI 0.125 to 0.423], relative risk for TAD > 15 mm = 0.404 [95% CI 0.270 to 0.606]; p < 0.001, power for difference > 99%). The median radiation time for the CAS cohort was lower than the median radiation time for the conventional cohort (median 1.4 minutes versus median 1.7 minutes, median difference 0.3 minutes; p = 0.002, power for difference = 81%). No difference in median total operating time was found for the CAS procedures compared with the conventional procedures (median 36 minutes versus median 38 minutes, median difference 2 minutes; p = 0.227, power for difference = 18%, power for equivalency = 93%). There was no difference in cut-out noted with the use of the CAS compared with the conventional technique with the numbers available. Based on the current results, the upper 95% probability for a cutout complication ranges from 0% to 5% in the CAS cohort versus 0% to 9% in the conventional cohort (difference of upper 95% CI = 4%). CONCLUSION: CAS use is associated with a decrease in median TAD with less variation and fewer outliers during cephalomedullary nailing. Compared with the conventional technique, fewer outliers were noted with the CAS at the standard TAD threshold of 25 mm and a lower TAD threshold of 15 mm. Additional research is needed to determine the association of TAD variation and outliers on cut-out and to determine if there is any clinical value to the decrease in TAD variation and outliers noted here. The patient and surgical team are exposed to less radiation with the CAS compared with the conventional technique, but this difference is small and it is unclear if this benefit justifies CAS use. Incorporating CAS into the cephalomedullary nailing procedure is not associated with a change in operative time, so there are no costs or risks associated with increased operative time. More procedures would be needed to provide adequate power to better analyze the risk of lag screw cut-out, allowing a more complete understanding of the value of this technology compared with its cost. LEVEL OF EVIDENCE: Level III, therapeutic study.

Enhanced cephalomedullary nail lag screw placement and intraoperative tip-apex distance measurement with a novel computer assisted surgery system.

OBJECTIVE: The goal of this study was to evaluate the ability of a novel computer assisted surgery system to guide ideal placement of a lag screw during cephalomedullary nailing and then accurately measure the tip-apex distance (TAD) measurement intraoperatively. DESIGN: Retrospective case review. SETTING: Level II trauma hospital. PATIENTS: The initial 98 consecutive clinical cases treated with a cephalomedullary nail in conjunction with a novel computer assisted surgery system were retrospectively reviewed. INTERVENTION: A novel computer assisted surgery system was utilized to enhance lag screw placement during cephalomedullary nailing procedures. The computer assisted surgery system calculates the TAD intraoperatively after final lag screw placement. MAIN OUTCOME MEASURES: The ideal TAD was considered to be within a range of 5mm-20mm. The ability of the computer assisted surgery system (CASS) to assist in placement of a lag screw within the ideal TAD was evaluated. Intraoperative TAD measurements provided by the computer assisted surgery system were then compared to standard postoperative TAD measurements on PACS (picture archiving and communication system) images to determine whether these measurements are equivalent. RESULTS: 79 cases (80.6%) were available with complete information for a retrospective review. All cases had CASS TAD and PACS TAD measurements >5mm and<20mm. In addition, no significant difference could be detected between the intraoperative CASS TAD and the postoperative PACS TAD (p=0.374, Wilcoxon Test; p=0.174, paired T-Test). A cut-out rate of 0% was observed in all patients who were treated with CASS in this case series (95% CI: 0 - 3.01%). CONCLUSIONS: The novel computer assisted surgery system tested here is an effective and reliable adjunct that can be utilized for optimal lag screw placement in cephalomedullary nailing procedures. The computer assisted surgery system provides an accurate intraoperative TAD measurement that is equivalent to the standard postoperative measurement utilizing PACS images. LEVEL OF EVIDENCE: Therapeutic Level IV.

Biomechanical comparison of a lateral polyaxial locking plate with a posterolateral polyaxial locking plate applied to the distal fibula.

BACKGROUND: Polyaxial locking plates are becoming popular for the fixation of distal fibula fractures. This study establishes how construct stiffness and plate loosening, measured as range of motion, differs between lateral and posterolateral plate location. METHODS: Seven matched pairs of cadaver fibulae were osteotomized in standardized fashion to produce a Weber type B distal fibula fracture. The fragments were fixated with an interfragmentary lag screw and polyaxial locking plates, with one fibula in each pair receiving a posterolateral anti-glide-plate, and the other a lateral neutralization-plate. In a biomechanical test, the bending and torsional stiffnesses of the constructs and the ranges of motion (ROM) were measured and subjected to a paired comparison. RESULTS: The laterally plated group had a higher median (interquartile range) bending stiffness (29.2 (19.7) N/mm) and a smaller range of motion (2.06 (1.99) mm) than the posterolaterally plated group (14.6 (20.6) N/mm, and 4.11 (3.28) mm, respectively); however, the results were not statistically significant (pbending=0.314; pROM=0.325). Similarly, the torsional stiffness did not differ significantly between the two groups (laterally plated: 426 (259) Nmm/°; posterolaterally plated: 248 (399) Nmm/°; ptorsion=0.900). The range of motion measurements between the two groups under torsional loading were also statistically insignificant (laterally plated: 8.88 (6.30) mm; posterolaterally plated: 15.34 (12.64) mm; pROM=0.900). CONCLUSION: In biomechanical cadaver-model tests of Weber type B fracture fixation with polyaxial locking plates, laterally plated constructs and posterolaterally plated constructs performed without significantly difference. Therefore, other considerations, such as access morbidity, associated injuries, patient anatomy, or surgeon's preference, may guide the choice of plating pattern. Further clinical studies will be needed for the establishment of definitive recommendations. CLINICAL RELEVANCE: Information on the behavior of polyaxial locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.

Critical factors in cut-out complication after Gamma Nail treatment of proximal femoral fractures.

BACKGROUND: The most common mechanical failure in the internal fixation of trochanteric hip fractures is the cut-out of the sliding screw through the femoral head. Several factors that influence this complication have been suggested, but there is no consensus as to the relative importance of each factor. The purpose of this study was to analyse the cut-out complication with respect to the following variables: patients' age, fracture type, fracture reduction, implant positioning and implant design. METHODS: 3066 consecutive patients were treated for trochanteric fractures with Gamma Nails between 1990 and 2002 at the Centre de Traumatologie et de l'Orthopedie (CTO), Strasbourg, France. Cut-out complications were identified by reviewing all available case notes and radiographs. Subsequently, the data were analysed by a single reviewer (AJB) with focus on the studied factors. RESULTS: Seventy-one cut-out complications were found (2.3%) of the 3066 trochanteric fractures. Cut-out failure associated with avascular head necrosis, pathologic fracture, deep infection or secondary to prior failure of other implants were excluded from the study (14 cases). The remaining 57 cases (1.85%, median age 82.6, 79% females) were believed to have a biomechanical explanation for the cut-out failure. 41 patients had a basicervical or complex fracture type. A majority of cut-outs (43 hips, 75%) had a combination of the critical factors studied; non-anatomical reduction, non-optimal lag screw position and the characteristic fracture pattern found. CONCLUSIONS: The primary cut-out rate of 1.85% was low compared with the literature. A typical cut-out complication in our study is represented by an unstable fracture involving the trochanteric and cervical regions or the combination of both, non-anatomical reduction and non-optimal screw position. Surgeons confronted with proximal femoral fractures should carefully scrutinize preoperative radiographs to assess the primary fracture geometry and fracture classification. To reduce the risk of a cut-out it is important to achieve both anatomical reduction and optimal lag screw position as these are the only two factors that can be controlled by the surgeon.

Locally enhanced early bone formation of zoledronic acid incorporated into a bone cement plug in vivo.

OBJECTIVES: The aim of the study was to gain experience about the short-term effects of zoledronic acid (ZOL) on bone-implant contact (BIC), bone regeneration and bone area (BA). METHODS: In this in-vivo study, ZOL was released locally from a drug-loaded pre-shaped calcium phosphate bone cement plug which was implanted into a bone defect in the proximal tibia of rats. At 1 and 3 weeks post implantation, tissue reactions as well as bone regeneration capabilities at the implant site were investigated. Furthermore, tissue samples, harvested at placebo and verum plug sites were used to analyse the gene expression of selected bone-specific markers by using quantitative polymerase chain reaction. Data were normalized against ribosomal RNA (Rn18s) subunits. KEY FINDINGS: In the placebo interface a higher amount of cells could be detected as indicated by higher expression of small subunit Rn18s. Nevertheless, comparing the normalized data of the selected gene expression levels, no significant differences were detected. The histomorphometric results showed a significant higher BIC and BA for ZOL-loaded plugs at 3 weeks after implantation. CONCLUSIONS: In this model, ZOL was demonstrated to be effective in impacting the bone regeneration process towards reduction of early bone resorption and enhanced bone formation.

Short-term outcome of retrograde tibiotalocalcaneal arthrodesis with a curved intramedullary nail.

BACKGROUND: The aim of this study was to investigate the potential clinical benefit of tibiotalocalcaneal arthrodesis (TTCA) with an intramedullary nail with a valgus curve, two compression options, and angle-stable locking. MATERIAL AND METHODS: Patients who had undergone TTCA at two tertiary hospitals were eligible. Patients who had undergone TTCA before the beginning of the study were evaluated retrospectively, then all following patients were examined prospectively. There were 59 TTCAs; 55 patients were available for analysis. Twenty-eight were evaluated retrospectively, 27 prospectively. Main Outcome Measures were an SF-36, Mazur-, and AOFAS ankle-hindfoot rating scores and radiographic examination. RESULTS: Bony union was obtained in 53 patients. Fifty-one patients were satisfied with the outcome. Fifty-one patients had marked subjective improvement in mobility. The mean AOFAS score of the 55 patients at the latest followup was 66.8 (range, 38 to 86). The mean Mazzur score was 68.0 (range, 30 to 83). In the prospective group, the scores were significantly improved: AOFAS score by an average of 39.6 points (p<0.001); Mazur score by an average of 43 points (p<0.001); SF-36 physical component summary score (p<0.001) and mental component summary score also improved (p<0.048). Radiology showed good hindfoot alignment. The complication rate was 25%. CONCLUSION: Compared with the literature, the data obtained in this study show a good outcome and a high rate of bony union, with comparable complication rates. Patient satisfaction was good. However, the patients still had limitations. The clinical benefit of the nail used was confirmed.

3066 consecutive Gamma Nails. 12 years experience at a single centre.

BACKGROUND: Fixation of trochanteric hip fractures using the Gamma Nail has been performed since 1988 and is today well established and wide-spread. However, a number of reports have raised serious concerns about the implant's complication rate. The main focus has been the increased risk of a subsequent femoral shaft fracture and some authors have argued against its use despite other obvious advantages, when this implant is employed. Through access to a uniquely large patient data base available, which is available for analysis of trochanteric fractures; we have been able to evaluate the performance of the Gamma Nail over a twelve year period. METHODS: 3066 consecutive patients were treated for trochanteric fractures using Gamma Nails between 1990 and 2002 at the Centre de Traumatologie et de l'Orthopedie (CTO), Strasbourg, France. These patients were retrospectively analysed. Information on epidemiological data, intra- and postoperative complications and patients' outcome was retrieved from patient notes. All available radiographs were assessed by a single reviewer (AJB). RESULTS: The results showed a low complication rate with the use of the Gamma Nail. There were 137 (4.5%) intraoperative fracture-related complications. Moreover 189 (6.2%) complications were detected postoperatively and during follow-up. Cut-out of the lag screw from the femoral head was the most frequent mechanical complication (57 patients, 1.85%), whereas a postoperative femoral shaft fracture occurred in 19 patients (0.6%). Other complications, such as infection, delayed healing/non-union, avascular femoral head necrosis and distal locking problems occurred in 113 patients (3.7%). CONCLUSIONS: The use of the Gamma Nail in trochanteric hip fractures is a safe method with a low complication rate. In particular, a low rate of femoral shaft fractures was reported. The low complication rate reported in this series can probably be explained by strict adherence to a proper surgical technique.

The use of a retrograde fixed-angle intramedullary nail for tibiocalcaneal arthrodesis after severe loss of the talus.

Tibiocalcaneal arthrodesis may be the only means of obtaining a painless and stable limb when there is loss of the talus. We present the early results of a prospective study on tibiocalcaneal arthrodesis using a latest-generation retrograde intramedullary nail. In the period 2006-2007, nine patients underwent tibiocalcaneal arthrodesis with retrograde intramedullary nailing. Five of these patients had infection-related loss of the talus. SF-36, AOFAS ankle-hindfoot, and Mazur Ankle Arthrodesis scores were obtained pre-fusion, and at 6 weeks, 6 months and 1 year post-fusion. The patients were also followed up clinically and radiologically. Previous surgical procedures, chronic musculoskeletal problems and other comorbidities, and complications were recorded and analyzed. All patients were available for initial follow-up and were subjectively satisfied with their outcomes. Solid fusion was achieved and fully confirmed in nine cases. One subject died 8 weeks postoperatively of a pulmonary embolism. One patient had recurrent infection. At 1 year, only one patient still needed NSAIDs regularly for pain relief. The AOFAS score improved significantly (P = 0.012) from 32.1 pre-fusion to 71.5 points at 1 year as did the Mazur score, which rose by 31.2 to 72.5 points at 1 year (P = 0.012). The SF-36 score improved significantly in the domains physical functioning, role limitations due to physical problems, bodily pain, vitality, social functioning and mental health, as did the Physical Component Summary Score. Retrograde intramedullary nailing for tibiocalcaneal arthrodesis can produce a good outcome. However, in the presence of infection, patient selection for intramedullary procedures must be carefully considered on a case-by-case basis.

Results of the T2 humeral nailing system with special focus on compression interlocking.

BACKGROUND: The outcome of interlocking nailing of humeral shaft fractures is controversial. Variations in implants, operative technique and follow-up parameters hinder comparative studies. The aim of this investigation was to evaluate the T2 humeral nailing system according to clinical results, and to recognise advantages and disadvantages of compression interlocking. METHODS: A total of 36 consecutive humeral shaft fractures were treated with an interlocking humeral nail. In 23 cases the antegrade and in 14 cases the retrograde approach was used. Compression locking was performed in 21 and static locking in 15 cases. RESULTS: At 22-month follow-up, bone consolidation was present in 35 cases; in 5 cases complications developed. There was no significant difference between compression and static locking nor between the antegrade and retrograde approach regarding complications, Constant shoulder score, mean Morrey elbow score, SF-12 physical score or SF-12 mental score. CONCLUSION: Antegrade and retrograde interlocking nailing of humeral shaft fractures with the T2 nailing system can result in good functional outcome and unimpaired quality of life. Compression interlocking can minimise the fracture gap and increase the biomechanical stiffness. Potential disadvantages of compression interlocking include possible bending or loosening of the locking screw in the dynamic oblong hole. An additional static locking screw should be used on the humerus after compression interlocking.

Comparison of two intramedullary nails for tibiotalocalcaneal fusion: anatomic and radiographic considerations.

BACKGROUND: Retrograde intramedullary nailing is an established procedure for tibiotalocalcaneal arthrodesis. This study was conducted to see whether, and if so to what extent, nail design modifications would influence the risk to anatomic structures and the bony coverage of the nail base. METHODS: Six pairs of thawed fresh-frozen cadaver legs received two different intramedullary nails (N1: straight nail, lateral-medial tip locking; N2: valgus-curved nail, medial-lateral tip locking) under simulated operative conditions. The specimens were dissected; distances between the at-risk structures and the hardware were measured. The hindfoot axis and the volume of the intracalcaneal nail portion were determined with CT. RESULTS: At the plantar entry site, N2 was significantly farther from the flexor hallucis longus tendon (p=0.047), the medial plantar artery (p=0.026), and the lateral plantar nerve (p=0.026) than N1. The lateral-medial calcaneal locking screw of N1 damaged significantly more often the peroneus brevis tendon (p=0.03) than N2. The proximal tip-locking screw, N2, was significantly farther from the anterior tibial artery (p=0.075) and the deep (p=0.047) and superficial peroneal nerves (p=0.009) than N1; N1 was significantly farther from the great saphenous vein (p=0.075) than N2. The distal tip-locking screw, N1. damaged significantly more often the extensor digitorum longus (p=0.007), the anterior tibial artery(p = 0.04), and the deep and superficial peroneal nerves (p=0.03) than N2. CT did not show any significant changes in the hindfoot axis with either device; intracalcaneal nail volumes were similar. CONCLUSIONS: A curved nail can increase the distance to at-risk plantar structures. Medial-lateral nail-tip locking appears to have less risk to neurovascular structures. CLINICAL RELEVANCE: Safer retrograde intramedullary nailing for tibiotalocalcaneal fusion requires knowledge of the structures at risk and appropriate operative technique.

Reliability of the transepicondylar axis as an anatomical landmark in total knee arthroplasty.

Femoral component malalignment after total knee arthroplasty is known to cause clinical symptoms, such as anterior knee pain. For intraoperative referencing, several anatomical landmarks are used by surgeons. One frequently used landmark is the transepicondylar axis, yet the accuracy and reproducibility of defining this axis have not been established. In 6 human cadavers, 4 different experienced orthopedic surgeons performed selections of the most prominent points of the medial and lateral epicondyle. Each individual position was digitized and recorded by an accurate optical navigation system. In addition, the most prominent points of the medial and lateral epicondyle were defined on a computed tomography image. After transforming the cadaver points in the computed tomography coordinate system, distances to the epicondyles were measured. The overall distribution of selected points was located in an area of 278 mm2 upon the medial epicondyle and 298 mm2 of the lateral.