Occult intra-operative periprosthetic fractures of the acetabulum may affect implant survival.

PURPOSE: Occult intra-operative periprosthetic acetabular fracture is a seldom-reported complication of primary total hip arthroplasty (THA). It may potentially be associated with cup instability and implant loosening. The present study aimed to investigate clinical consequences of this complication. METHODS: Between 2003 and 2012, a total of 3390 cementless total hip arthroplasties (THA) were performed at our institution. Their medical histories were retrospectively reviewed to identify all patients who received a thin-layer computer tomography (CT) scan of the pelvis including the acetabulum within the first 30 post-operative days. They were evaluated and classified by two radiologists independently with respect to the presence of recent acetabular fractures. All cases with acetabular and periacetabular fractures were included in this study. Electronic medical records were reviewed to assess implant revision. Cup stability was measured with EBRA (Einzel-Bild-Röntgen-Analyse) from plain X-rays. RESULTS: Periprosthetic fractures of the acetabulum were identified in 58 (50.4%) of 115 selected patients. Fractures close to but not including the acetabulum were identified in 45% (n = 26/58) of the patients, at the superolateral wall in 17% (n = 10/58), at the anterior wall of the acetabulum in 16% (n = 9/58) and in 10% (n = 6/58) each at the medial wall, and at the posterior wall respectively. One out of these 58 fractures could not be classified. Three of a total of six occult medial wall fractures had to be revised, and another two showed a high implant migration. The highest cup migration values however were found after fractures of the superolateral wall. Incomplete column fractures did not influence implant survival. CONCLUSION: Central wall acetabular fractures, although unrecognized intra- and post-operatively may impair implant survival after THA.

Analysing outcomes through orthopaedic trauma registry - A prospective cohort study.

OBJECTIVE: To develop a registry for recording injury-specific data to identify gaps and improve care. Methods: The prospective cohort study was conducted at Aga Khan University Hospital, Karachi, from June 2015 to July 2018 though enrollment of patients with limb trauma is continuing to date. Data on injuries and management related to Tibia shaft fractures was collected from medical records, and outcomes were assessed on follow-up visits. Internationally validated injury-specific scores were utilised for assessing functional, clinical and radiological outcomes. SPSS version 19 was used for data analysis. Results: There were 763 patients with 825 limb injuries. Of the injuries, 310(37.6%) related to upper limbs and 515(62.4%) to the lower limbs. Management was surgical for 741(89.9%) and conservative for 84(10.1%) injuries. Overall, 12(1.57%) patients died, and in 7(0.91%) cases mortality was unrelated to trauma and its management. There were 105 patients with tibia shaft fractures. Of them, 88(83.8%) were males and 17(16.2%) were females. At one-year follow-up excellent-to-good results were 12(92%) for intramedullary nailing followed by 7(78%) for open reduction and internal fixation. Conclusion: Registry data can be used to develop preventive strategies and to improve management protocols.

Periprosthetic Occult Fractures of the Acetabulum Occur Frequently During Primary THA.

BACKGROUND: Periprosthetic fractures of the acetabulum occurring during primary THA are rare. Periprosthetic occult fractures are defined as those not identified by the surgeon during the procedure which might be missed on a routine postoperative radiograph. However, it is unclear how frequently these fractures occur and whether their presence affects functional recovery. QUESTIONS/PURPOSES: In this study, using routine CT scans that were obtained as part of another primary hip arthroplasty study protocol, we retrospectively assessed (1) the prevalence of occult fractures of the acetabulum occurring during primary THA, (2) the location of occult fractures of the acetabulum during THA, and (3) risk factors contributing to such occult fractures. METHODS: Between 2004 and 2013, our institute performed 585 primary THAs (cementless or hybrid) in 494 patients with DICOM pre- and postoperative CT; during the period in question, all patients undergoing THA underwent CT before and after surgery. Preoperative CT images were taken as part of a CT-based three-dimensional templating software and navigation system. Postoperative CT images were taken an average of 1 week after surgery as part of a different protocol to evaluate cup position, restoration of leg length and offset, volume of postoperative hematoma to assess anticoagulation effects after THA, and fractures that were not found on routine postoperative radiographs (which we defined as occult fractures). Patients with a history of prior pelvic osteotomy, trauma, and infection were excluded (88 patients/99 hips); 406 patients (102 males and 304 females; 486 hips) form the basis of this report. The mean age of the patients was 60 ± 11 years, with a mean BMI of 23 ± 4 kg/m2. The mean followup of the patients with periprosthetic fracture of the acetabulum was 58 ± 28 months (range, 12-131 months). Potential risk factors for occult acetabular fracture including age, sex, BMI, preoperative diagnosis, additional dome screw fixation, composition and size of each cup, and acetabular design were examined in multivariate analysis. Acetabular component designs were categorized as true hemispheric, peripheral self-locking, and elliptical; during the period in question the indications for each cup design were based on the brand of stem used. Comparison between preoperative and postoperative CT images was done to detect the fractures. Patients with fractures identified during surgery were treated with additional dome screw fixation and a 3-week period of nonweightbearing. Patients with occult fractures in this series did not receive additional treatment as we had confirmed secure fixation of the cup during surgery. RESULTS: Occult fractures occurred in 41 hips (8.4%); periprosthetic fractures of the acetabulum were seen during surgery in an additional two hips (0.4%). The superolateral wall was the most frequent location for occult fractures of the acetabulum. After controlling for relevant confounding variables, only the use of peripheral self-locking cups was associated with an increased risk of occult fracture (odds ratio [OR], 2.6 compared with hemispheric cups; 95% CI, 1.2-5.6; p < 0.05). All patients with occult fractures showed bone ingrowth fixation at the final followup, without any additional surgical intervention. CONCLUSIONS: Periprosthetic occult fractures of the acetabulum may occur relatively frequently during press-fit impaction. We observed a higher rate of fractures associated with the use of peripheral self-locking components. Occult acetabular fractures not detected on routine postoperative plain films may be ignored if secure fixation of the cup has been confirmed during the operation. LEVEL OF EVIDENCE: Level III, therapeutic study.

Prevalence of exclusively and concomitant pelvic fractures at magnetic resonance imaging of suspect and occult hip fractures.

Pelvic fractures may occur together with hip fractures as a result of low energy trauma. It is unclear whether they do require special attention. There are conflicting results in the literature about the prevalence of both concomitant hip and pelvic fractures as well as exclusive pelvic fractures. It has been reported that hip fractures and obturator ring fractures are mutually exclusive. To retrospectively analyze the prevalence of exclusively pelvic as well as concomitant hip and pelvic fractures in patients examined with MRI after low-energy trauma in elderly. During 9 years, 316 elderly patients had been examined with MRI for suspected or occult hip fracture after a fall. A fracture was diagnosed when MRI showed focal signal abnormalities in the subcortical bone marrow, with or without disruption of adjacent cortices. One observer reviewed all studies. A second observer verified all studies with hip fractures. Follow-up was available for all but two patients that died prior to hip surgery. The prevalence of concomitant pelvic and femoral neck or trochanteric fractures was statistically compared using chi-squared test for categorical variables. Hip fractures were found in 161 (51 %) patients of which 29 (9 %) had concomitant pelvic fractures. There were exclusively pelvic fractures in 82 (26 %) patients of which 65 (79 %) were on the traumatized side only. In 73 patients, there were no fractures. Occult or suspected hip fractures are not infrequently associated with pelvic fractures. Exclusively pelvic fractures are not uncommon.

Radiographic diagnosis of occult distal fibular avulsion fracture in children with acute lateral ankle sprain.

BACKGROUND: Skeletally immature children with ankle sprain are presumed to have distal fibula fracture than ligamentous injury. The purpose of this study is to determine the incidence of associated occult avulsion fracture in children with lateral ankle sprain and the efficacy of identifying fractures using anterior talofibular ligament view. METHODS: Patients who were diagnosed with distal fibular fracture in the initial ankle anteroposterior, lateral, and mortise were excluded and 78 patients (below 16 y of age) who had been initially diagnosed as ankle sprain were included. The initial and 4 weeks' follow-up ankle series and additional anterior talofibular ligament view suggested by Haraguchi were evaluated. RESULTS: Twenty patients were diagnosed with occult distal fibular avulsion fracture. Ten patients were diagnosed in anterior talofibular ligament view and others were diagnosed in the follow-up radiography. Displacement was highest on the anterior talofibular ligament view. CONCLUSIONS: This study found 20 (26%) of 78 ankle sprain show occult avulsion fracture in the anterior talofibular ligament view or follow-up radiography. The anterior talofibular ligament view is an appropriate radiologic view for the diagnosis of distal fibular avulsion fracture. LEVEL OF EVIDENCE: Level IV--diagnostic study.

The use of ultrasound to detect occult or unsuspected fractures in child abuse.

Occult fractures due to child abuse can be difficult to identify because there is usually no history of trauma, and chief complaints are vague. In addition, the osseous injuries are often subtle, becoming obvious only after healing begins. Missed injuries can lead to inappropriate disposition of a patient and can cause children to be placed at high risk for further injury and death. It is therefore imperative that these children be diagnosed as soon as possible. Ultrasound has some properties that are desirable for detecting fractures, especially in children. Ultrasound waves are almost completely reflected by cortical bone. Thus, fractures easily appear on an ultrasound screen. The cartilaginous nature of pediatric bones makes some fractures difficult to identify on x-ray. The nature of ultrasound waves, however, allows the cartilaginous areas of pediatric bones to be identified. This brief report presents 2 cases of children younger than 1 year presenting with vague complaints (limp, irritability) without a history of trauma. Both children underwent bedside ultrasound by a pediatric emergency medicine physician with training in emergency ultrasound. The bedside ultrasound led to the identification of occult or unsuspected fractures in both children, and state social services were notified. In both cases, the cause of the fracture was determined to be from abuse, and necessary measures were taken to ensure the child's future safety. This report demonstrates that ultrasound may be useful for early identification of some types of occult or unsuspected fractures commonly seen in cases of child abuse.

Callus formation is related to the expression ratios of estrogen receptors-alpha and -beta in ovariectomy-induced osteoporotic fracture healing.

INTRODUCTION: This study characterizes ovariectomized (OVX)-induced osteoporotic fracture healing with focus on estrogen receptors (ERs). Callus formation plays a critical role in fracture healing, and ERs are well-known mechanosensors in osteogenic pathways. It was hypothesized that callus formation was related to and partially determined by the difference in expression patterns of ERs in both normal and OVX-induced osteoporotic fractures. METHODS: Closed femoral fracture in SHAM and ovariectomized rats were used in this study. Weekly callus width (CW) and area (CA), endpoint mechanical properties, gene expressions of Col-1, BMP-2, ER-α, ER-ß and ER-α:ER-ß ratios (ER-ratios), and correlations were assessed at 2, 4 and 8 weeks post-fracture. RESULTS: CW and CA results confirmed that OVX-induced osteoporotic fracture was delayed at 2-4 weeks with impaired endpoint mechanical properties. Gene expressions of ER-α and ER-ß were higher in the SHAM group at week 2 (p < 0.05) and later lowered at week 8; whereas the OVX group showed an opposing trend. Moderate correlation existed between ER-α and BMP-2 (0.545, p = 0.003), and ER-ratio and BMP-2 (0.601, p = 0.001), and BMP-2 to CW and CA (r = 0.709, p = 0.000 and r = 0.588, p = 0.001, respectively). ER-α and ER-ß proteins expressions were confirmed by immunohistochemistry at the fracture callus in reparative progenitor cells, osteoblasts- and osteoclasts-like cells. CONCLUSION: We conclude that the delayed healing rate and impaired callus quality in OVX-induced osteoporotic fracture is related to the delayed expression of ERs. A high ER-α:ER-ß ratio favors callus formation.

The rate of nonunion in the MRI-detected occult scaphoid fracture.

Aims: There is a lack of published evidence relating to the rate of nonunion seen in occult scaphoid fractures, diagnosed only after MRI. This study reports the rate of delayed union and nonunion in a cohort of patients with MRI-detected acute scaphoid fractures. Methods: This multicentre cohort study at eight centres in the UK included all patients with an acute scaphoid fracture diagnosed on MRI having presented acutely following wrist trauma with normal radiographs. Data were gathered retrospectively for a minimum of 12 months at each centre. The primary outcome measures were the rate of acute surgery, delayed union, and nonunion. Results: A total of 1,989 patients underwent acute MRI for a suspected scaphoid fracture during the study period, of which 256 patients (12.9%) were diagnosed with a previously occult scaphoid fracture. Of the patients with scaphoid fractures, six underwent early surgical fixation (2.3%) and there was a total of 16 cases of delayed or nonunion (6.3%) in the remaining 250 patients treated with cast immobilization. Of the nine nonunions (3.5%), seven underwent surgery (2.7%), one opted for non-surgical treatment, and one failed to attend follow-up. Of the seven delayed unions (2.7%), one (0.4%) was treated with surgery at two months, one (0.4%) did not attend further follow-up, and the remaining five fractures (1.9%) healed after further cast immobilization. All fractures treated with surgery had united at follow-up. There was one complication of surgery (prominent screw requiring removal). Conclusion: MRI-detected scaphoid fractures are not universally benign, with delayed or nonunion of scaphoid fractures diagnosed only after MRI seen in over 6% despite appropriate initial immobilization, with most of these patients with nonunion requiring surgery to achieve union. This study adds weight to the evidence base supporting the use of early MRI for these patients.

Traumatic floating clavicle.

We report a case of traumatic floating clavicula in a man aged 21 years. He was admitted to our emergency department with polytrauma sustained in a motor car accident, successfully treated 21 days after the accident with bipolar open reduction and wire stabilization.

Occult femoral neck fracture associated with vitamin D deficiency diagnosed by MRI: case report.

Hip fractures in the young are exceedingly rare and are usually seen in instances of high energy trauma or metabolically altered bone states. In this case report, we present an occult femoral neck fracture, diagnosed by magnetic resonance imaging, in an otherwise healthy, young, active duty male patient with an isolated vitamin D deficiency treated using cannulated percutaneous screws.

Epidural hematoma associated with occult fracture in ankylosing spondylitis patient: a case report and review of the literature.

STUDY DESIGN: A case report and review of the literature. OBJECTIVE: To highlight the risk of occult fracture associated with symptomatic epidural hematoma in patient with ankylosing spondylitis. SUMMARY OF BACKGROUND DATA: Hyperextension injuries are common in patients with ankylosed spine. Failure of standard imaging to detect these fractures may result in delayed diagnosis. Ossification of the ligaments in these patients makes even subtle fractures grossly unstable owing to the increased lever arm. Delayed diagnosis of fractures may result in further displacement and increased risk of neurological injury. METHODS: The clinical findings, roentgenographic appearance, and treatment were presented. RESULTS: A 69-year-old patient with a history of ankylosing spondylitis fell 9 feet from a ladder. The patient developed pain in his neck and numbness in his hands. Initial computed tomography (CT) scan of spine showed a subtle fracture in the vertebral body of C7. A magnetic resonance imaging scan showed an epidural hematoma extending from C5 to T3. The patient was taken to the operating room urgently for decompression. Laminectomy was performed from C5 to T3 and a large epidural hematoma was evacuated. After decompression the patient had some improvement in his neurological status. A postdecompression repeat CT scan revealed obvious fracture at C6-C7 with anterior distraction indicating a hyperextension injury. The patient was taken back to the operating room within 16 hours of his decompression for C4 to T3 posterior segment instrumentation and fusion. CONCLUSIONS: Patients with ankylosing spondylitis who sustain low-energy injuries should be considered to have a fracture especially if they develop epidural hematoma. A high index of suspicion is necessary in such a case. Imaging studies including magnetic resonance imaging and CT scans should be reviewed carefully to rule out any occult fracture.

Pediatric tibial shaft and distal metaphyseal fractures.

OBJECTIVES: This study aims to investigate the effects of associated factors like age, fracture level, accompanying fibular fractures and wound condition on healing by determining and comparing union scores of pediatric tibial fractures (PTFs). PATIENTS AND METHODS: Forty-five patients with 46 PTFs (32 males, 13 females; mean age 9.5 years; range 2 to 16 years) who were treated by closed reduction and casting or operated between January 2016 and January 2019 were retrospectively evaluated. The union scores were evaluated at the end of fourth, sixth and eighth weeks and compared to each other. Effects of the age, associated fibular fractures, wound condition, fracture level and treatment type to union score were analyzed. RESULTS: Twenty-eight (60.9%) out of 46 PTFs had associated fibular fractures and 18 (39.1%) did not. Motor vehicle accident was the most frequent etiologic factor (47.8%). Thirty-four out of 46 fractures were closed tibial fractures (73.9%) and 12 had open wound (26.1%). There was a negative correlation between age and the union scores (p<0.001 for each week). No significant difference was observed between the union score of diaphyseal and metaphyseal fractures at the fourth, sixth, and eighth weeks. The union scores of each week were higher in the conservative group compared to operative group (p<0.001 for each week). Associated fibular fracture group had lower union scores compared to isolated tibial fracture group at fourth, sixth and eighth weeks. Likewise, the union scores of the open fracture group were lower than the closed fracture group (p<0.05 for each week). CONCLUSION: Associated fibular fractures, open fractures and aging negatively affect union scores of PTFs. Attention should be paid, particularly in these conditions, during the selection of the operation type and the follow-up period of PTFs.

A noncontiguous 2-level spinal injury in a young female driver due to a 3-point seat belt restraint.

OBJECTIVES: The purpose of this case is to describe noncontiguous fracture and dislocations of the thoracolumbosacral spine in a 23-year-old female driver with a 3-point seat belt restraint. CLINICAL FEATURES: A 23-year-old woman presented to us after a motor vehicle accident while driving with a 3-point seat belt restraint. She was neurologically intact except for loss of motor function in the distribution of the L5 nerve root in the right lower limb. Computed tomography and magnetic resonance imaging showed fracture and dislocation of T3 with considerable retrolisthesis and complete anterolisthesis of L5 over the sacrum. INTERVENTION AND OUTCOME: Both fractures were reduced and fixed with bone graft and instrumentation. She was discharged a month later without any further neurologic deterioration. CONCLUSIONS: To our knowledge, this case is the first report in the literature of a seat belt safety restraint causing 2 noncontiguous fracture dislocations of the spine. Although the consensus is that seat belts can prevent most spine injuries, this case shows that the seat belt can be a contributor to spine injury. It shows that the shoulder-lap restraint can act as 2 fulcrums at the upper and lower bands causing 2 separate fracture dislocations. A thorough radiologic evaluation of the spine with respect to the clinical findings is mandatory in seat belt-restrained road traffic accidents cases.

[Nasal bone fracture: etiology, diagnostics, treatment and complications]. / Die Fraktur des Os nasale: Unfallmechanismen, Diagnostik, Therapie und Komplikationen.

BACKGROUND: The aim of the present evaluation was to analyse a large patient population with nasal bone fractures leading to surgical reposition of the nasal bone. Special attention was paid to age summit, the distribution of the seasons, the rate of open compared to closed nasal bone fractures, accompanying injuries, diagnosis and therapy as well as to the postoperative course. METHODS: A total of 300 patients was evaluated retrospectively. All patients had been treated between 1999 and 2004 regarding simple and complex nasal bone fractures. Data were analysed with regard to history, age, gender, diagnosis, therapy, results, and complications. RESULTS: The average age of the patients was 29.6+/-15.6 years at the time of fracture with clear predominance of the male gender (77%). Another age summit could be observed in patients of >60 years. The main reasons for nasal bone fracture were falls (30%), in elderly patients often caused by cardiac syncopes, and rows (28%). The most frequent findings were deviation of the longitudinal axis of the nose (59%) and traumatic deviation of the nasal septum (50%). 65 patients (22%) had open nasal bone fractures, in 5% of the cases septal hematoma could be observed. CONCLUSION: Closed reposition of the nasal bone is the therapy of choice in uncomplicated nasal bone fractures. Special attention has to be paid to the group of patients aged 60 years and older who often suffer from treatment requiring comorbidities. In these cases inpatient treatment must be considered.

Salter-Harris Type III Fracture in a Football Player.

A 15-year-old high school football player sustained direct impact to his anteromedial left knee by a teammate's helmet during practice. The physician referred the athlete immediately to an after-hours clinic for imaging to rule out a fracture. Radiographs of the knee showed a nondisplaced Salter-Harris type II fracture. The treating physician also ordered magnetic resonance imaging, the results of which allowed for a more specific diagnosis of the fracture as a Salter-Harris type III fracture of the left femur.J Orthop Sports Phys Ther 2019;49(3):209. doi:10.2519/jospt.2019.7984.

[Patellar tendon rupture with distal closed fracture of the ipsilateral femur]. / Rupture du tendon rotulien avec fracture fermée distale du fémur homolatéral.

We here report the case of a 45-year old patient who had injured his right knee because of a road accident. The patient had right comminuted supracondylar femur fracture and ipsilateral patellar tendon rupture. This association is exceptional and no case has been reported in the literature. Targeted clinical and radiological diagnostic tests followed by early and suitable management based on internal osteosynthesis and suitable early functional rehabilitation enabled good long term outcome.

Use and Utility of Skeletal Surveys to Evaluate for Occult Fractures in Young Injured Children.

OBJECTIVE: To describe the percentage and characteristics of children aged <24 months with non-motor vehicle crash (MVC)-related injuries who undergo a skeletal survey and have occult fractures. METHODS: We performed a retrospective chart review of a stratified, systematic random sample of 1769 children aged<24 months with non-MVC-related bruises, burns, fractures, abdominal injuries, and head injuries at 4 children's hospitals between 2008 and 2012. Sampling weights were assigned to each child to allow for representative hospital-level population estimates. Logistic regression models were used to test for associations between patient characteristics with outcomes of skeletal survey completion and occult fracture identification. RESULTS: Skeletal surveys were performed in 46.3% of children aged 0 to 5 months, in 21.1% of those aged 6 to 11 months, in 8.0% of those aged 12 to 17 months, and in 6.2% of those aged 18 to 24 months. Skeletal surveys were performed most frequently in children with traumatic brain injuries (64.7%) and rib fractures (100%) and least frequently in those with burns (2.1%) and minor head injuries (4.4%). In adjusted analyses, older age, private insurance, and reported history of accidental trauma were associated with decreased skeletal survey use (P ≤ .001 for all). The prevalence of occult fractures on skeletal surveys ranged from 24.6% in children aged 0 to 5months to 3.6% in those aged 18 to 24 months, and varied within age categories based on the presenting injury (P < .001). CONCLUSIONS: The high rate of occult fractures in infants aged 0 to 5 months underscores the importance of increasing the use of skeletal surveys in this population. Further research is needed to identify the injury characteristics of older infants and toddlers most at risk for occult fractures.

Chest computed tomography imaging utility for radiographically occult rib fractures in elderly fall-injured patients.

BACKGROUND: Previous studies demonstrate an association between rib fractures and morbidity and mortality in trauma. This relationship in low-mechanism injuries, such as ground-level fall, is less clearly defined. Furthermore, computed tomography (CT) has increased sensitivity for rib fractures compared with chest x-ray (CXR); its utility in elderly fall patients is unknown. We sought to determine whether CT-diagnosed rib fractures in elderly fall patients with a normal CXR were associated with increased in-hospital resource utilization or mortality. METHODS: Retrospective analysis of emergency department patients presenting over a 3-year period. INCLUSION CRITERIA: age, 65 years or older; chief complaint, including mechanical fall; and both CXR and CT obtained. We quantified rib fractures on CXR and CT and reported operating characteristics for both. Outcomes of interest included hospital admission/length of stay (LOS), intensive care unit (ICU) admission/LOS, endotracheal intubation, tube thoracostomy, locoregional anesthesia, pneumonia, in-hospital mortality. RESULTS: We identified 330 patients, mean age was 84 years (±SD, 9.4 years); 269 (82%) of 330 were admitted. There were 96 (29%) patients with CT-diagnosed rib fracture, 56 (17%) by CT only. Compared with CT, CXR had a sensitivity of 40% (95% confidence interval, 30-50%) and specificity of 99% (95% confidence interval, 97-100%) for rib fracture. A median of two additional radiographically occult rib fractures were identified on CT. Despite an increased hospital admission rate (91% vs. 78%) p = 0.02, there was no difference between patients with and without radiographically occult (CT+ CXR-) rib fracture(s) for: median LOS (4; interquartile range (IQR) 2-7 vs 4, IQR 2-8); p = 0.92), ICU admission (28% vs. 27%) p = 0.62, median ICU LOS (2, IQR 1-8 vs 3, IQR 1-5) p = 0.54, or in-hospital mortality (10.3% vs. 7.3%) p = 0.45. CONCLUSION: Among elderly fall patients, CT-identified rib fractures were associated with increased hospital admissions. However, there was no difference in procedural interventions, ICU admission, hospital/ICU LOS or mortality for patients with and without radiographically occult fractures. LEVEL OF EVIDENCE: Diagnostic, level III.

Occult periprosthetic femoral fractures occur frequently during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA.

The present study aimed to investigate the prevalence and clinical consequences of occult intra-operative periprosthetic femoral fractures in total hip arthroplasty (THA). Between 2012 and 2017, a total of 113 primary THAs were enrolled. The mean age of the patients was 66.4 ± 7.6 years. We assessed occult intra-operative periprosthetic femoral fractures with the use of computed tomography (CT) and risk factors, including age, sex, body mass index, diagnosis, stem size, and radiographic parameters of proximal femoral geometry were analyzed. We also assessed the differences in thigh pain and stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. Occult intra-operative periprosthetic femoral fractures were found in 13 of 113 hips (11.5%). In 9/13 (69.2%) of occult fractures, fracture lines were started from the region below the tip of the lesser trochanter. Six periprosthetic femoral fractures (5.3%) were found during the operation. Out of the five hips that had detected femoral fractures around the lesser trochanter intra-operatively, four hips (80%) showed concurrent occult fractures on different levels. The female sex (P = .01) and canal filling ratio at 7 cm below the tip of the lesser trochanter (P = .01) were significantly different between the patients with and without occult periprosthetic femoral fracture. The sex was significantly associated with an increased risk in predicting an occult intra-operative periprosthetic femoral fracture (odds ratio of male, 0.25 compared with the female; 95% CI, 0.08-0.85; p = .02). There was a significant difference in the incidence of thigh pain between occult fracture group and non-occult fracture group (P < .05). There were no significant differences in stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. All 13 cases of occult intra-operative periprosthetic femoral fractures were healed at the final follow-up. Occult periprosthetic femoral fractures are common during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA, that CT scans are helpful to identify them, and that these fractures do not adversely affect the implant's survival if a rigid fixation of the implants has been achieved.