Single-leg-stance radiographs in the diagnosis of pelvic instability

The myth of 2.5 cm symphyseal diastasis

Detection of disruption of the pubic symphysis and resulting anterior pelvic ring instability primarily depends on the symphyseal widening on standard anterior-posterior X-rays. Based on biomechanical and clinical analyses from the 80 to 90's, a cut-off value of 2.5 cm widening distinguished between stable and unstable lesions. A relevant debate developed concerning minor (< 2.5 cm displacement), moderate (> 2.5 cm displacement) and severe disruptions (> 2.5 cm displacement + posterior complete pelvic ring instability) of the pubic symphysis. Analysis of anatomic, biomechanical, physiological and clinical literature showed, that an exact value does not allow this differentiation. Thus, symphyseal posttraumatic disruptions with displacements > 10 mm should be treated surgically, while in minor displacements (5-10 mm) stress examination can guide adequate treatment.

Accuracy of an image matching technique for assessing knee alignment during the stance phase of gait using single-plane anteroposterior radiography

BACKGROUND

Accurate measurement of bone alignment of the knee during walking provides ideal clinical information for diagnosis and treatment of knee joint disorders. To bring this ideal closer to clinical reality, we developed an image matching technique to measure the three-dimensional (3D) position of bones using anteroposterior radiography during the stance phase of treadmill walking.

OBJECTIVE

To develop and validate an image matching method for evaluation of 3D knee alignment using anteroposterior radiography of artificial femoral and tibial bones.

METHODS

The 3D position of each bone was recovered by minimizing the difference between the projected outline and the contour of the bone in the anteroposterior radiograph. The true value of the position was measured using a 3D coordinate measuring machine.

RESULTS

The mean values ± standard deviation and root mean squares (RMS) of translation errors were within -1.6 ± 2.1 mm and 2.6 mm, respectively, for femur, and 2.1 ± 1.9 mm and 2.8 mm for tibia. The mean values ± standard deviation and RMS of errors in rotation were within 0.3 ± 0.7° and 0.7°, respectively, for femur, and -0.3 ± 0.9° and 0.9°, respectively, for tibia.

CONCLUSION

Our method is suitable for evaluating 3D knee alignment on anteroposterior radiography.

The EMS stress view: occult pelvic instability revealed by pre-hospital pelvic binder placement

PURPOSE

To describe and evaluate the serendipitous pelvic binder stress radiographs of lateral compression type (LC) pelvic ring injuries.

METHODS

This was a retrospective case series performed at a single, level I academic trauma center from 2016 to 2018. All patients presenting with a minimally displaced LC pelvic ring injury were reviewed (< 10 cm displacement on static pelvic radiographs). Patients with X-rays (XR) in a pelvic binder (EMS stress) and with the pelvic binder removed were included. Pelvic ring stability was determined by attending surgeon evaluation of EMS stress radiographs versus static XR of the pelvis. Patients were treated non-operatively and allowed to weight bear or taken to the operating room for exam under anesthesia (EUA) and potential operative fixation. Clinical success of treatment was determined by evaluation of further displacement at the completion of their most recent follow-up.

RESULTS

Thirty-seven patients of the initial 398 reviewed met inclusion criteria. Fourteen of 37 patients (38%) were categorized as stable with no significant pelvis displacement seen on EMS stress and were treated non-operatively without further sequelae (4.6 months mean follow-up). The remaining 23/37 (62%) were treated operatively. Occult instability was identified on EMS stress in 14 (61%) of those 23 patients and the remainder were determined to be unstable based upon fracture pattern or EUA. All patients went on to successful treatment without significant pelvic deformity (7.8 months mean follow-up).

CONCLUSION

The EMS stress XR is a valuable, opportunistic evaluation in LC pelvic ring injuries. This evaluation is a useful diagnostic adjunct to alert the provider that additional stress imaging may be indicated to evaluate for occult pelvic ring instability.

The clinical relevance of fixation failure after pubic symphysis plating for anterior pelvic ring injuries: an observational cohort study with long-term follow-up

BACKGROUND

Open reduction and plate fixation is a standard procedure for treating traumatic symphyseal disruptions, but has a high incidence of implant failure. Several studies have attempted to identify predictors for implant failure and discussed its impact on functional outcome presenting conflicting results. Therefore, this study aimed to identify predictors of implant failure and to investigate the impact of implant failure on pain and functional outcome.

METHODS

In a single-center, retrospective, observational non-controlled cohort study in a level-1 trauma center from January 1, 2006, to December 31, 2017, 42 patients with a plate fixation of a traumatic symphyseal disruption aged ≥ 18 years with a minimum follow-up of 12 months were included. The following parameters were examined in terms of effect on occurrence of implant failure: age, body mass index (BMI), injury severity score (ISS), polytrauma, time to definitive treatment, postoperative weight-bearing, the occurrence of a surgical site infection, fracture severity, type of posterior injury, anterior and posterior fixation. A total of 25/42 patients consented to attend the follow- up examination, where pain was assessed using the Numerical Rating Scale and functional outcome using the Majeed Pelvic Score.

RESULTS

Sixteen patients had an anterior implant failure (16/42; 37%). None of the parameters studied were predictive for implant failure. The median follow-up time was six years and 8/25 patients had implant failure. There was no difference in the Numerical Rating Scale, but the work-adjusted Majeed Pelvic Score showed a better outcome for patients with implant failure.

CONCLUSION

implant failure after symphyseal disruptions is not predictable, but appears to be clinically irrelevant. Therefore, an additional sacroiliac screw to prevent implant failure should be critically discussed and plate removal should be avoided in asymptomatic patients.

Diagnostic accuracy of MRI for detection of occult instability of type I anterior to posterior pelvic injuries

Type I Young and Burgess anterior posterior compression (APC) pelvic injuries have been classically managed non operatively due to theoretical integrity of sacroiliac joint ligaments (SIJL), though examination under anesthesia (EUA) has been proven occult mechanical instability in up to 50% of these injuries.  We sought to determine the diagnostic accuracy of magnetic resonance (MRI) for detection of occult instability on APC-I injuries when compared to EUA.

METHODS

Diagnostic test study of prospectively recruited patients admitted with APC-I pelvic injuries between 2015 and 2022. All patients consented to participate in this study were subjected to MRI and EUA. The evaluators of each of these tests were blinded.  On MRI evaluation, SIJL were considered compromised when unilateral injury to anterior SIJL was visualized in three or more consecutive images or in bilateral injuries, when injury to the anterior SIJL in two or more consecutive images on each side was observed. Positive EUA was considered a symphyseal diastasis over 25 mm on stress fluoroscopy. Demographic data was collected as recruited and sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. Confidence interval was set at 95%. EUA was considered the gold standard in statistical analysis.

RESULTS

A total of 32 patients mean aged 36 (24-61) years were included. Mean symphyseal diastasis at admission was 17.58 (11 - 25) mm. The median time from injury to EUA was 5 (0-21) days. Positive EUA was observed on 20 patients and 25 patients  presented compromised SIJL. MRI presented a sensitivity of 95% (75.13% - 99.87%), specificity of 50% (21.09% - 78.91%), positive-predictive value of 73% (60.61% to 82.93%), negative-predictive value of 87% (48.66% - 98.08%).

CONCLUSION

Injury to SIJL on MRI presented an accuracy of 77% (58.29% - 89.64%) for the detection of occult pelvic instability on EUA.

Can preoperative radiographs predict hardware complication or fracture displacement after operative treatment of pelvic ring injuries?

INTRODUCTION

Operative fixation of pelvic ring injuries is associated with a high risk of hardware failure and loss of reduction. The purpose of this study was to determine whether preoperative radiographs can predict failure after operative treatment of pelvic ring injuries and if the method of fixation effects their risk.

PATIENTS AND METHODS

We conducted a retrospective cohort study of 143 patients with pelvic ring injuries treated with operative fixation at a level 1 trauma center. Preoperative radiographs were examined for the presence of the following characteristics: bilateral rami fractures, segmental or comminuted rami fractures, contralateral anterior and posterior injuries, complete sacral fracture, and displaced inferior ramus fractures. The method of fixation was classified based on the presence of anterior, posterior, or combined anterior and posterior fixation as well as whether or not posterior fixation was performed at a single or multiple sacral levels. Post-operative radiographs were examined for hardware failure or loss of reduction.

RESULTS

Twenty-one patients (14.7%) demonstrated either hardware complication or fracture displacement within 6 months of surgery. Male sex was associated with a decreased risk of hardware complication (OR 0.11 [0.014, 0.86]; p=0.03). Posterior pelvic ring fixation at multiple sacral levels was associated with a decreased risk of fracture displacement (OR 0.21 [0.056, 0.83]; p=0.02). We were unable to demonstrate a significant association between preoperative radiographic characteristics and risk of hardware failure or fracture displacement.

CONCLUSION

Our study demonstrates that both gender and the method of posterior fixation are associated with hardware failure or displacement.

Chronic Anterior Pelvic Instability

Introduction:

Chronic anterior pelvic instability means pathologic movement of the symphysis pubis with axial load. It is not a common pathology and its diagnosis is often delayed and difficult increasing the disability of affected patients. The pain is localized in the suprapubic area or groins, increasing with physical activity, direct palpation or compression. Main known causes are pregnancy, delivery, trauma, fractures, intense physical activity, infection, or previous surgeries. Treatment algorithms have not been standardized. Initially, it is managed with an orthosis, physical activity modification, medication, and rehabilitation. Surgical treatment with symphyseal arthrodesis is the last option. The literature on symphyseal plating for chronic instability found is sparse.

Case Report:

We report the case of a 33-year-old female presenting lower abdominal pain after her third delivery. Several months after, magnetic resonance imaging and scintigraphy suggested chronic symphysitis. Single leg stance pelvic X-rays indicated chronic anterior pelvic instability. Pain-relievers, physical rehabilitation, and local corticosteroid injection were noneffective; surgery was indicated, performing a double plate symphyseal arthrodesis with iliac bone graft.

Conclusion:

Pelvic instability should be ruled out when persistent abdominal or lower back pain are present. Thorough physical examination and specific provocative maneuvers need to be assessed. In our presented case, symphyseal arthrodesis was performed without complications. After a two-year follow-up, the patient has recovered her previous functional status and bone scintigraphy is negative. Radiologic controls rule out loosening or material breaking as a complication. We hope this case report may give a clue in surgical options management.

A novel radiological projection of the pelvis to evaluate the sitting imbalance in pelvis nonunions and malunions

INTRODUCTION

Inadequate initial management of unstable pelvic injuries is usually associated with a fracture non-union and/or mal-union. Complete clinical and imaging evaluation is mandatory for a correct preoperative planning. Among other symptoms, sitting discomfort may arise from asymmetry of the ischial tuberosities or pressure from a prominent bony projection. Conventional radiographs are usually taken with the individual in a supine position and not in position where the symptoms are referred. We attempted to define a new radiological projection different than the regular pelvis views to study the position of pelvis of a normal person in sitting position. The second objective was to demonstrate its utility in the evaluation of a pelvic deformity.

MATERIAL AND METHODS

Fifteen healthy individuals were evaluated with a radiological projection in a sitting position. One patient with a vertically migrated pelvis nonunion was also evaluated with the same radiological protocol.

RESULTS

In each volunteer's radiological study, a parallel line could be drawn between the sitting table and both distal aspects of the ischial tuberosities, sacral alas and superior aspect of the iliac wings. A plumb line perpendicular to the above mentioned ones could be drawn uniting the vertebras' spinous processes. A 90⁰ line intersection confirms the absence of deformity. In the pathological case, a pseudo scoliosis of the thoracolumbar spine is detected trying to compensate the pelvis obliquity and maintain equilibrium.

CONCLUSIONS

We determined normal and pathological radiological features in the sitting imbalance of the pelvic in the anteroposterior plane of the pelvis. The study helps to understand the biomechanics and compensation of the pelvis to define surgical indications and predict post correction anatomy.

Chronic Anterior Pelvic Instability: Diagnosis and Management

Chronic anterior pelvic ring instability can cause pain and disability. Pain typically is localized to the suprapubic area or inner thigh; often is associated with lower back or buttock pain; and may be exacerbated by activity, direct impact, or pelvic ring compression. Known etiologies of chronic anterior pelvic ring instability include pregnancy, parturition, trauma, insufficiency fractures, athletics, prior surgery, and osteitis pubis. Diagnosis often is delayed. Physical examination may reveal an antalgic or waddling gait, tenderness over the pubic bones or symphysis pubis, and pain with provocative maneuvers. AP pelvic radiographs may demonstrate chronic degenerative changes at the pubic symphysis or nonhealing fractures. Standing single leg stance (flamingo view) radiographs can demonstrate pathologic motion at the pubic symphysis. CT may be useful in assessing posterior pelvic ring involvement. The initial management is typically nonsurgical and may include the use of an orthosis, activity modification, medication, and physical therapy. If nonsurgical modalities are unsuccessful, surgery may be warranted, although little evidence exists to guide treatment. Surgical intervention may include internal fixation alone in select patients, the addition of bone graft to fixation, or symphyseal arthrodesis. In some patients, additional stabilization or arthrodesis of the posterior pelvic ring may be indicated.

Editorial Commentary: The Hip Bone's Connected to the Spine Bone-But Correlation Does Not Equal Causation

A significant correlation was observed between the degree of lumbar spine arthritis and 2 quantitative markers of cam morphology (alpha angle and anterior femoral head-neck offset) in a large osteological collection of cadaveric lumbar spine and femurs. Although this study does not prove causation, it does impart further insight into the "hip-spine syndrome" in nonarthritic hips with proximal femoral asphericity.

Posterior symphyseal spurs--an unusual differential diagnosis in athletes with groin pain

We set out to highlight the significance of posterior symphyseal spurs as an unusual diagnostic possibility in athletes with chronic groin pain and to demonstrate that operative resection was successful in quickly and safely returning the patients to sporting activities. Five competitive nonprofessional male athletes, three soccer players, and two marathon runners (median age: 30 [26/33] years), who presented to us with significant groin and central pubic pain with duration of at least 12 months, and who had failed conservative or surgical interventions (symphyseal plating), were evaluated. Physical examination as well as pelvic radiographs confirmed the diagnosis of posterior symphyseal spurs. Four out of five athletes underwent complete resection of the spur. Size of spurs was 2.2 (1.3/2.9) cm (median) with four of them posterosuperiorly and one posterocentrally located. All of them had uneventful postoperative recovery period and were still pain-free at the latest follow up after 26.6 months (24/30). Median time-to-return to competitive sports level was 10 weeks (8/13). None of the patients developed pubic instability due to symphyseal spur resection. The results of considerable postoperative improvement in our patients highlight the significance of posterior symphyseal spurs as a diagnostic possibility in athletes with chronic groin pain.

Radiosteriometric analysis of movement in the sacroiliac joint during a single-leg stance in patients with long-lasting pelvic girdle pain

BACKGROUND

Chamberlain's projections (anterior-posterior X-ray of the pubic symphysis) have been used to diagnose sacroiliac joint mobility during the single-leg stance test. This study examined the movement in the sacroiliac joint during the single-leg stance test with precise radiostereometric analysis.

METHODS

Under general anesthesia, tantalum markers were inserted into the dorsal sacrum and the ilium of 11 patients with long-lasting and severe pelvic girdle pain. After two to three weeks, a radiostereometric analysis was conducted while the subjects performed a single-leg stance.

FINDINGS

Small movements were detected in the sacroiliac joint during the single-leg stance. In both the standing- and hanging-leg sacroiliac join, a total of 0.5 degree rotation was observed; however, no translations were detected. There were no differences in total movement between the standing- and hanging-leg sacroiliac joint.

INTERPRETATION

The movement in the sacroiliac joint during the single-leg stance is small and almost undetectable by the precise radiostereometric analysis. A complex movement pattern was seen during the test, with a combination of movements in the two joints. The interpretation of the results of this study is that, the Chamberlain examination likely is inadequate in the examination of sacroiliac joint movement in patients with pelvic girdle pain.

Management of pelvic injuries in pregnancy

Pelvic fractures in pregnant women are usually high-energy injuries associated with risk of mortality to both mother and fetus. The mother's life always takes priority in the acute setting as it offers the best chance of survival to both the mother and the fetus. Indications for operative intervention of acute pubic symphysis rupture depend on presence of an open disruption, amount of displacement, and degree of disability. Chronic symphyseal instability related to pregnancy is a challenging problem and the first line of treatment is nonoperative care. A previous pelvic fracture is not a contraindication by itself to vaginal delivery.

Internal fixation of symphyseal disruption resulting from childbirth

OBJECTIVES

To investigate the clinical and radiographic results after operative treatment of complete symphyseal disruption resulting from childbirth and to evaluate residual pain and implant failure in relation to the timing of surgery.

DESIGN

Retrospective study.

SETTING

Tertiary pelvis and acetabulum care unit at a general hospital.

PATIENTS

Ten consecutive women with complete symphysis disruption associated with childbirth were included from a database of 603 patients with pelvic fracture. No patients with this diagnosis were excluded. All patients were followed until clinical healing of the symphysis or union of the fusion.

INTERVENTION

Open reduction and internal fixation in acute (less than 2 weeks from childbirth, four patients) and after failed nonoperative treatment in subacute cases (2 weeks to 6 months after childbirth, three patients). Fusion of the symphysis with iliac crest bone graft and plate fixation after failed nonoperative treatment in chronic cases (greater than 6 months, three patients).

MAIN OUTCOME MEASUREMENT

Analyzed variables included the Lindahl score, maintenance of postoperative reduction, implant failure, malunion, and necessity of reoperation.

RESULTS

Mean age of the patients was 32 years (range, 24-37 years). Mean follow up was 29 months (range, 5-139 months). The mean postoperative Lindahl score was 68 ± 14.6 points (range, 38-80 points). There were three excellent, four good, two fair, and one poor result. Fair or poor results occurred in one subacute and two chronic cases. There were two revision surgeries. One patient underwent implant removal resulting from dyspareunia 3.1 years postoperatively. One subacute patient had conversion to symphyseal fusion after implant failure as a result of a fall 11 years after index surgery. Major complications occurred in two and minor complications in three patients. Radiographic loosening of implants was observed in all subacute cases. All fusions healed and symptoms improved at last follow up.

CONCLUSIONS

Operative management significantly improved the functional outcomes of all three subgroups and can be an acceptable treatment option for labor-induced complete symphysis pubis disruption.

Stress radiograph to detect true extent of symphyseal disruption in presumed anteroposterior compression type I pelvic injuries

BACKGROUND

The differentiation between anteroposterior compression (APC)-I and APC-II pelvic fracture patterns is critical in determining operative versus nonoperative treatment. We instituted a protocol in which a stress examination was performed for patients presenting with an APC-I injury diagnosed with static radiographs to reveal the true extent of the injury.

METHODS

During a 4-year study period, we performed 22 stress radiographs in patients with a presumed APC-I injury, which showed symphyseal diastasis ≥ 1.0 cm but <2.5 cm on initial anteroposterior (AP) radiographs of the pelvis or on axial images of the pelvis on computed tomography (CT) scans. In the operating room, a radiopaque marker of known diameter was placed on the skin over the pubic symphysis. A direct AP load was manually applied to both anterior superior iliac spines, and diastasis of the pubic symphysis was measured on stress fluoroscopic images.

RESULTS

The mean distance of symphyseal diastasis was 1.8 cm on the AP radiographs, 1.4 cm on the CT scans, and 2.5 cm on fluoroscopic images under a stress examination. Six of 22 patients (27.2%) demonstrated a symphyseal diastasis of >2.5 cm during the stress examination, which changed their treatment from nonoperative to operative.

CONCLUSIONS

Measurements of symphyseal diastasis can significantly vary depending on the radiographic modality (CT vs. plain films) and during application of a stress force. The use of stress examination under general anesthesia in the acute setting of pelvic injury can be beneficial in accurately diagnosing the severity of injury and choosing appropriate treatment.

Stress radiographs in orthopaedic surgery

Stress radiographs are useful in determining the amount of ligamentous laxity present following trauma. The results may be helpful in determining diagnosis, surgical indications, and the type and timing of rehabilitation. Some techniques for obtaining stress radiographs involve specific patient positioning or manually applied force; others require use of a particular testing device. Stress radiographs may be obtained for a variety of anatomic areas and joints. The parameters that define abnormality on stress radiographs should be compared with those of clinical findings. The use of common and novel methods to obtain stress radiographs has led to improved identification and diagnosis of many orthopaedic pathologies. Some of these techniques have been developed with the aim of reducing patient discomfort or minimizing the clinician's exposure to radiation.