Nonoperative Treatment of Posterior Wall Acetabular Fractures After Dynamic Stress Examination Under Anesthesia: Revisited.

OBJECTIVES: Performing an examination under general anesthesia (EUA) using dynamic stress fluoroscopy of patients with posterior wall acetabular fractures has been used as a tool to determine hip stability and the need for surgical intervention. The purpose of this study was to further evaluate the effectiveness of this technique, from a source other than its primary advocates, in patients with posterior wall acetabular fractures less than or equal to 50% who were stable on EUA and treated nonoperatively. DESIGN: Retrospective case series. SETTING: University Level 1 Trauma Center. PARTICIPANTS: Seventeen patients with a posterior wall acetabular fracture stable on EUA treated nonoperatively. INTERVENTION: The patients were treated nonoperatively as guided by an EUA negative for instability. Patient follow-up averaged 30 months (range, 6-64 months). MAIN OUTCOME MEASUREMENTS: Outcome evaluation included the modified Merle d'Aubigné clinical score and the Short Musculoskeletal Function Assessment Questionnaire. Radiographic evaluation for subluxation or arthritis consisted of the 3 standard pelvic radiographs. RESULTS: Radiographic evaluation showed all hips to be congruent with a normal joint space. Sixteen of the 17 patients had radiographic outcomes rated as "excellent"; 1 patient was rated "good." The modified Merle d'Aubigné score (obtained in 12 patients) averaged very good, with only 1 having less than a good (graded as fair) clinical outcome. The Short Musculoskeletal Function Assessment Questionnaire scores (from 11 patients) were not significantly different from normal and were within the normal reported values for all indices and categories. There was no correlation between fracture fragment size and outcome. CONCLUSIONS: This study further supports the contention that a stable hip joint, as determined by EUA, after posterior wall acetabular fracture treated nonoperatively is predictive of continued joint congruity, an excellent radiographic outcome, and good-to-excellent early clinical and functional outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Which Anterior Acetabular Fracture Surgical Approach is Preferred? A Survey of the Orthopaedic Trauma Association Active Membership.

OBJECTIVE: The goal of this survey was to determine the current surgeon-preferred anterior surgical approach for the treatment of acetabular fractures in North America. DESIGN: Web-based survey; PARTICIPANTS:: Orthopaedic Trauma Association (OTA) members. METHODS: Active members of the OTA were solicited to participate in an OTA-sponsored survey asking for their preferred standard anterior surgical approach to the acetabulum, along with some general demographic data. The approach choices were: the classic ilioinguinal as described by Letournel, a modified ilioinguinal, the modified Stoppa (Anterior Intrapelvic) with or without a lateral window, the pararectus, and an alternative to be specified by the survey taker. RESULTS: Of the 675 total active OTA membership, 214 (32%) satisfactorily completed the survey. Of the 214 active members, only 32 (15%) prefer the classic ilioinguinal approach and 60 (28%) prefer some type of modified ilioinguinal approach. More than half of the active member respondents (121; 56.5%) prefer the modified Stoppa approach. Statistical analysis of the respondents' demographic data revealed only years in practice to be significantly different among treatment options (P < 0.01) with those with the least time in practice preferring the modified Stoppa. CONCLUSIONS: It seems that the modified Stoppa has become the preferred anterior acetabular fracture surgical approach in North America, being especially favored by those more recently in practice. The exact reasons for this change cannot be determined from this survey and are most likely multifactorial. However, training experience may play an important role.

Venous thromboembolism after hospital discharge in pelvic and acetabular fracture patients treated operatively.

PURPOSE: The purposes of this study were to determine the rate of venous thromboembolism (VTE) after discharge from the hospital in patients treated operatively with a pelvic ring or acetabular fracture and to define the main time frame in which VTE occurs within the 90-day period after hospital discharge. METHODS: California and Florida State Inpatient Databases from 2005 to 2009 were used to identify patients with clinically significant VTEs within 90 days of hospital discharge. ICD-9 diagnosis codes identified patients with a pelvic ring or acetabular fracture and a VTE. Procedure codes distinguished patients having surgical fracture treatment. Deep vein thrombosis (DVT) and pulmonary embolus (PE) were included. RESULTS: Overall, 13,589 patients had a pelvic ring or acetabular fracture and operative treatment. One hundred thirteen patients (0.83%) had a VTE within 90 days after hospital discharge: 69 (0.51%) had a DVT, 28 (0.21%) had a PE, and 16 (0.12%) had both. Twenty-four (28%) of DVTs and 10 (23%) of PEs occurred >35 days after discharge, being evenly distributed out to 90 days. There were five fatal PEs, occurring 2, 3, 7, 31, and 51 days after discharge. Therefore, overall, <0.2% of patients developed a DVT and <0.1% were diagnosed with a PE (only 1 fatal; <0.01%) >35 days after the index hospitalization. CONCLUSIONS: A substantial proportion of VTE events occur over 35 days after discharge; however, the overall risk is low with fatal PE being extremely low (<0.01%). Given the diminished VTE risk after 35 days, the decision to further extend antithrombotic drug therapy may be guided by patient-specific factors, such as prolonged immobility.

Current Trends in the Surgical Treatment of Open-Book Pelvic Ring Injuries: An International Survey Among Experienced Trauma Surgeons.

INTRODUCTION: In the open-book, rotationally unstable (OTA/AO type 61-B1.1) pelvic ring injury, the posterior sacroiliac complex is believed to remain intact. Therefore, anterior ring stabilization alone has been the standard treatment recommendation. However, treatment failures using this method have caused a reconsideration of this management strategy. Anterior plus posterior fixation is the main alternative. In the absence of any specific new guidelines, the choice of treatment currently relies on the preference of the treating surgeon. The objective of this survey was to determine the relative use of anterior plus posterior fixation, as opposed to the standard anterior fixation alone, for the treatment of open-book pelvic ring injuries. METHODS: An international group of 176 practicing trauma surgeons experienced in pelvic ring fracture fixation participated in an AO Foundation survey asking for their preferred standard surgical fixation (anterior alone or anterior plus posterior combined) for OTA/AO type 61-B1.1 open-book pelvic fractures. RESULTS: Anterior plate fixation alone (group 1) was preferred by 56% of the survey participants, and combined anterior plus posterior fixation (group 2) was preferred by 44%. Statistical analysis revealed that group 1 participants were significantly older than group 2 participants (P = 0.03) and had more years of surgical experience (P = 0.02). CONCLUSIONS: Concern regarding the inadequacy of anterior fixation alone has led many surgeons, especially those more recently in practice, to add posterior fixation, despite limited data to determine its indications. No doubt the OTA/AO type B 1.1 pelvic ring disruption actually represents a wide spectrum of injury. Further study is needed to determine the best fixation method.

Does Posterior Fixation of Partially Unstable Open-Book Pelvic Ring Injuries Decrease Symphyseal Plate Failure? A Biomechanical Study.

OBJECTIVE: Recent clinical study suggests an advantage to adding an iliosacral screw to the anterior fixation construct for anteroposterior compression type-2 (OTA/AO type 61-B1), partially unstable open-book pelvic ring injuries. Others have described stress examination to determine any required supplemental fixation. However, biomechanical studies investigating iliosacral fixation requirements for this injury are lacking. Our objective was to determine whether adding an iliosacral screw to symphyseal plate fixation decreases displacement in a well-defined open-book pelvic ring injury model. METHODS: An open-book pelvic ring injury was created in 10 human cadaveric pelves by unilaterally releasing the sacrospinous, sacrotuberous, and anterior sacroiliac ligaments plus transection of the pubic symphysis, approximating the classically described anteroposterior compression type-2 (APC-2) injury. Specimens were divided into 2 groups: (1) symphyseal plating and (2) plating plus an iliosacral screw. Using a standard bilateral stance model loaded at 550 N, displacement measurements were obtained at 210,000 and 500,000 cycles. RESULTS: Three specimens failed before 210,000 cycles because of technical errors and were excluded from analysis. For the remaining 7, there was no significant difference in displacement between the 2 groups, and none sustained implant failure. Post hoc analysis showed that a large sample size (45/group) would be required to detect any difference with 80% power, indicating a small effect size with limited clinical application. CONCLUSIONS: Adding an iliosacral screw to the symphyseal plate fixation does not provide improved biomechanical outcome in classically described APC-2 injuries. Clinically, stress examination may be useful to determine the need for supplemental posterior fixation in APC-2 injuries.

Instability of the Hip Joint After Posterior Acetabular Wall Fracture: Independent Risk Factors Remain Elusive.

BACKGROUND: Exact determinants of hip instability have not been established for fractures of the posterior wall of the acetabulum involving ≤50% of the wall. Therefore, examination of the hip under anesthesia (EUA) is routinely performed. Recently, the superior exit point of the fracture has been reported to be an important identifiable risk factor. Pre-existing adult hip dysplasia (developmental dysplasia of the hip [DDH]) is thought to have a similar role. The purpose of this study was to determine if any known radiographic measurements and signs associated with DDH, or any fracture characteristics, are independent risk factors for hip instability after fracture of the posterior wall of the acetabulum. METHODS: All patients with a posterior acetabular wall fracture (OTA 62.A1) treated at our institution between 2004 and 2015 were considered for the study. Inclusion criteria were an age of ≥18 years, an isolated posterior acetabular wall fracture involving ≤50% of the acetabular wall, adequate imaging, and documented EUA results. Evaluated variables included fracture fragment size, superior exit point of the fracture, center-edge angle, acetabular index, Tönnis angle, lateralized head sign, crossover sign, posterior wall sign, ischial spine sign, and hip version. Data were examined using univariate testing, followed by a multivariate logistic regression analysis. RESULTS: Sixty-eight patients met all of the inclusion criteria. Univariate analyses identified the posterior wall sign (p = 0.033), ischial spine sign (p = 0.030), and proximity of the superior exit point of the fracture to the acetabular dome (p = 0.044) as having a significant association with hip instability. However, multivariate logistic regression modeling revealed that none of these factors were significant independent risk factors. CONCLUSIONS: Consistent with previous studies, univariate analyses identified certain radiographic findings as significant risk factors for hip instability in the setting of a fracture of the posterior wall of the acetabulum. However, subsequent multivariate logistic regression modeling showed that no studied variable was an independent risk factor. Our results indicate that important factors leading to hip instability are yet to be identified or the contributions of the measured variables are relatively small. Therefore, EUA should remain the main clinical determinant of hip stability status. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Acetabular Fractures: A Problem-Oriented Approach.

The main goals of acetabular fracture management are to restore the congruity and stability of the hip joint. These goals are the same for all patients who have an acetabular fracture, regardless of the morphology or etiology of the fracture. Nevertheless, certain acetabular fracture types and several patient factors pose management challenges for surgeons. Therefore, surgeons who manage acetabular fractures must understand the distinctive features of acetabular fractures as well as the soft-tissue and patient-related factors that play a critical role in patient outcomes. Particular challenges in the management of acetabular fractures include acetabular fracture types that involve the posterior wall, acetabular fractures with soft-tissue concerns, acetabular fractures in patients with multiple injuries, and acetabular fractures in the geriatric population. Although the well-known protocols that were established by Judet and Letournel continue to be important guidelines for the management of acetabular fractures, the injury characteristics of acetabular fractures, the demographics of the patients in whom acetabular fractures occur, and the treatment options for acetabular fractures have evolved. Therefore, surgeons must be aware of new and more recently published information on acetabular fractures.

Device Sales Representatives in the Operating Room: Do We Really Need or Want Them? A Survey of Orthopaedic Trauma Surgeons.

INTRODUCTION: The purposes of this study were to determine the current attitude of orthopaedic trauma surgeons toward device sales representatives (DSRs), especially regarding their presence in the operating room (OR), and to establish the existence of any surgeon generational differences. METHODS: A survey was created using a 5-point Likert response scale, related to conflict of interest (COI) and attitudes toward DSRs. Participants were solicited from the Orthopaedic Trauma Association database of 384 active members and 127 (33%) completed the survey. Respondents were divided into 2 subcategories (Generation X vs. Baby Boomers). RESULTS: Overall, respondents viewed their DSRs favorably without any perception of COI. However, they perceived their peers as being at risk for COI (P ≤ 0.004). Generation X responders feel that DSRs should be in the OR for all cases, whereas Baby Boomers do not (P < 0.01). CONCLUSIONS: With one striking generational difference, most orthopaedic trauma surgeons feel that they need DSRs in the OR. Similar to other physician groups, they also feel that they are not subject to COI from salesman contact that affects their peers. Reasons for this perceived need and any related COI risk, and the opportunities to address both, require further study.

Anterior total hip arthroplasty using a metaphyseal bone-sparing stem: component alignment and early complications.

BACKGROUND: Limited-incision total hip arthroplasty (THA) preserves hip abductors, posterior capsule, and external rotators potentially diminishing dislocation risk. However, potential complications also exist, such as component malposition. Specific implants have been manufactured that enhance compatibility with this technique, while preserving metaphyseal bone; however, little data exists documenting early complications and component position. The purpose was to evaluate primary THA using a curved, bone-sparing stem inserted through the anterior approach with respect to component alignment and early complications. METHODS: In a retrospective analysis of 108 cases, the surgical technique was outlined and the occurrence of intraoperative fractures, postoperative dislocations, infection, and limb length inequality was determined. Femoral stem and acetabular cup alignment was quantified using the initial postoperative radiographs. Patient follow-up averaged 12.9 (range 2 to 36) months. RESULTS: There were eight (7.4 %) complications requiring revision surgery in three (2.8 %) patients with three (2.8 %) infections and three (2.8 %) dislocations. Intraoperative complications included one calcar fracture above the lesser trochanter. Leg length inequality >5 mm was present in three (2.8 %) patients. Radiographic analysis showed that femoral neutral alignment was achieved in 95 hips (88.0 %). All femoral stems demonstrated satisfactory fit and fill and no evidence of subsidence, osteolysis, or loosening. An average abduction angle of 44.8° (± 5.3) and average cup anteversion of 16.2° (± 4.2) were also noted. CONCLUSIONS: Although the technique with this implant and approach is promising, it does not appear to offer important advantages over standard techniques. However, the findings merit further, long-term study.

CT-generated radiographs in patients with pelvic ring injury: can they be used in lieu of plain radiographs?

BACKGROUND: Pelvic ring injury classification traditionally is made using plain radiographs. Recent studies suggest that computed tomography (CT)-generated images have higher diagnostic accuracy than plain films for the classification of acetabular fractures. However, similar studies have not been performed for pelvic ring injuries. The purpose of this study was to compare CT-generated and plain radiographs in terms of the ability of surgeons at different experience levels to identify pelvic injury type. METHODS: CT-generated and plain radiograph image sets were created from 15 pelvic ring injury patients with known classification morphology. Three groups, each consisting of three orthopaedic surgeons representing different levels of expertise, viewed these image sets and recorded their diagnoses. These diagnoses were compared to the gold standard findings of the treating physician and to each other. RESULTS: Overall, there was a significantly improved ability to correctly classify pelvic ring injury type by CT-generated radiographs as compared to plain radiographs (p < 0.01). However, analysis of the groups revealed that this difference was limited to the less experienced groups (p < 0.05). CONCLUSIONS: CT-generated radiographs are diagnostically beneficial for less experienced surgeons and at least as good as conventional plain radiographs for experienced surgeons in classifying pelvic ring injuries. Therefore, CT-generated radiographs may be clinically valuable: sparing the patient additional radiation exposure and discomfort by avoiding the reordering of plain radiographs when the initial studies are of poor quality, as well as serving as a possible alternative for supplemental initial injury plain radiographic views.

Does Modified Footwear Improve Gait After Ankle Arthrodesis?

Rocker bottom shoes are commonly recommended for patients who have undergone ankle arthrodesis. Limited data are available to support this recommendation. In the present case-control study, 2 groups of participants were identified for the investigation: a study group (SG) of 9 patients who had previously undergone ankle arthrodesis and a normal group (NG) of 9 healthy volunteers. Gait data were collected using a video recorder while the participants walked barefoot and wearing rocker bottom shoes. These data were analyzed using computer-based gait analysis software. The total motion was calculated and averaged for each group for walking barefoot and wearing rocker bottom shoes. All participants completed the Short Musculoskeletal Function Assessment and the American Orthopaedic Foot and Ankle Society questionnaires. The total motion of the SG wearing rocker bottom shoes increased 4.8° (range 3.4° to 6.9°) on mean average, an improvement compared with walking barefoot (p < .05). In the NG, the shoe wear had no effect on the total motion (p = .59). Although the total motion in the SG approached the mean average of the total motion of the NG, it remained significantly less than that of the NG (p < .05). Additionally, the SG scored worse than the NG on both outcomes questionnaires (p < .05). Rocker bottom shoes had no effect on gait velocity. In conclusion, rocker bottom shoes significantly improve the total motion of ankle arthrodesis patients toward normal.

The Acetabular Fracture Prognostic Nomogram: Does it Work for Fractures of the Posterior Wall?

OBJECTIVES: A recently proposed nomogram is an attempt to define the subset of acetabular fractures at risk for primary total hip arthroplasty (THA) within 2 years of open reduction and internal fixation (ORIF). Our objectives were to determine whether this nomogram provides information adequate to reliably (1) prognosticate outcome within 2 years after ORIF or (2) identify optimal initial treatment choice (THA vs. ORIF) for patients with a posterior wall fracture. DESIGN: Retrospective case series. SETTING: University level 1 Trauma Center. PATIENTS: From a database of consecutive posterior wall fractures treated by ORIF, 103 patients were identified for analysis: 6 with an unsatisfactory result at less than 2 years and 97 followed 2-14 years. INTERVENTION: Calculation of percent risk of requiring THA within 2 years using the nomogram. MAIN OUTCOME MEASUREMENTS: Comparison of this percent risk to the actual clinical outcome within 2 years after ORIF, measured in 2 ways: (1) THA performed (5 patients) and (2) overall unsatisfactory hip function determined by the modified Merle d'Aubigné score (9 patients total: the 5 with THA plus 4 additional without THA but having unsatisfactory hip function). RESULTS: The calculated percent risk ranged widely, with much overlap among patients having satisfactory or unsatisfactory results of ORIF. Statistical analysis did not yield a clinically useful positive predictive value: 0.25 [95% confidence interval (CI), 0.08-0.53] for THA and 0.44 (95% CI, 0.21-0.69) for an overall unsatisfactory clinical result. CONCLUSIONS: The acetabular fracture prognostic nomogram in its current form does not provide sufficient information to prognosticate outcome after ORIF or to determine appropriate surgical management for posterior wall fractures. LEVEL OF EVIDENCE: Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Supplemental S1 fixation for type C pelvic ring injuries: biomechanical study of a long iliosacral versus a transsacral screw.

BACKGROUND: A single iliosacral screw placed into the S1 vertebral body has been shown to be clinically unreliable for certain type C pelvic ring injuries. Insertion of a second supplemental iliosacral screw into the S1 or S2 vertebral body has been widely used. However, clinical fixation failures have been reported using this technique, and a supplemental long iliosacral or transsacral screw has been used. The purpose of this study was to compare the biomechanical effect of a supplemental S1 long iliosacral screw versus a transsacral screw in an unstable type C vertically oriented sacral fracture model. MATERIALS AND METHODS: A type C pelvic ring injury was created in ten osteopenic/osteoporotic cadaver pelves by performing vertical osteotomies through zone 2 of the sacrum and the ipsilateral pubic rami. The sacrum was reduced maintaining a 2-mm fracture gap to simulate a closed-reduction model. All specimens were fixed using one 7.0-mm iliosacral screw into the S1 body. A supplemental long iliosacral screw was placed into the S1 body in five specimens. A supplemental transsacral S1 screw was placed in the other five. Each pelvis underwent 100,000 cycles at 250 N, followed by loading to failure. Vertical displacements at 25,000, 50,000, 75,000, and 100,000 cycles and failure force were recorded. RESULTS: Vertical displacement increased significantly (p < 0.05) within each group with each increase in the number of cycles. However, there was no statistically significant difference between groups in displacement or load to failure. CONCLUSIONS: Although intuitively a transsacral screw may seem to be better than a long iliosacral screw in conveying additional stability to an unstable sacral fracture fixation construct, we were not able to identify any biomechanical advantage of one method over the other.

Do asymptomatic patients have normal function after percutaneous fixation of the posterior pelvic ring? A case-control pilot study.

BACKGROUND: Following treatment of a posterior pelvic disruption, residual deformity or associated injuries can adversely affect functional recovery. No study has been performed on gait and functional outcome after closed reduction and percutaneous screw fixation (CRPSF) of posterior pelvic disruption in clinically asymptomatic patients. The purpose of this study was to determine if gait and functional outcome are different from normal in asymptomatic patients with a posterior pelvic injury after CRPSF, serving as a pilot study in this regard. METHODS: Six asymptomatic patients with no grossly evident gait abnormality, treated by CRPSF for a posterior pelvic disruption, were included in the study (SG). A control group (CG) of six healthy volunteers was created. All participants completed the 12-Item Short Form Health Survey version 2 (SF-12v2), the Majeed Pelvic Score (MPS), and the Iowa Pelvic Score (IPS). In addition, the participants' gait was analyzed. RESULTS: Pelvic drop was significantly smaller on the uninjured side in the SG when compared to the injured side in the SG. There was no significant difference between the injured and uninjured side for other gait parameters within the SG. Knee angle at initial contact was significantly greater on the injured side when compared to the CG. The SG scored statistically worse than the CG on the Physical Component Summary part of the SF-12v2. However, when evaluated by age group using national mean scores, the SG differences were minimal. All six patients in our study scored "excellent" on both MPS and IPS. CONCLUSIONS: Despite having subclinical alterations in gait, asymptomatic pelvic ring injured patients show minimal, if any, evidence of impaired functional outcome following successful reduction of a posterior pelvic disruption treated by CRPSF.

Current management of posterior wall fractures of the acetabulum.

The general goals for treating an acetabular fracture are to restore congruity and stability of the hip joint. These goals are no different from those for the subset of fractures of the posterior wall. Nevertheless, posterior wall fractures present unique problems compared with other types of acetabular fractures. Successful treatment of these fractures depends on a multitude of factors. The physician must understand their distinctive radiologic features, in conjunction with patient factors, to determine the appropriate treatment. By knowing the important points of posterior surgical approaches to the hip, particularly the posterior wall, specific techniques can be used for fracture reduction and fixation in these often challenging fractures. In addition, it is important to develop a complete grasp of potential complications and their treatment. The evaluation and treatment protocols initially developed by Letournel and Judet continue to be important; however, the surgeon also should be aware of new information published and presented in the past decade.

Nonoperative Treatment of Posterior Wall Acetabular Fractures After Dynamic Stress Examination Under Anesthesia: Revisited.

OBJECTIVES: Performing an examination under general anesthesia (EUA) using dynamic stress fluoroscopy of patients with posterior wall acetabular fractures has been used as a tool to determine hip stability and the need for surgical intervention. The purpose of this study was to further evaluate the effectiveness of this technique, from a source other than its primary advocates, in patients with posterior wall acetabular fractures less than or equal to 50% who were stable on EUA and treated nonoperatively. DESIGN: Retrospective case series. SETTING: University Level 1 Trauma Center. PARTICIPANTS: Seventeen patients with a posterior wall acetabular fracture stable on EUA treated nonoperatively. INTERVENTION: The patients were treated nonoperatively as guided by an EUA negative for instability. Patient follow-up averaged 30 months (range, 6-64 months). MAIN OUTCOME MEASUREMENTS: Outcome evaluation included the modified Merle d'Aubigné clinical score and the Short Musculoskeletal Function Assessment Questionnaire. Radiographic evaluation for subluxation or arthritis consisted of the 3 standard pelvic radiographs. RESULTS: Radiographic evaluation showed all hips to be congruent with a normal joint space. Sixteen of the 17 patients had radiographic outcomes rated as "excellent"; 1 patient was rated "good." The modified Merle d'Aubigné score (obtained in 12 patients) averaged very good, with only 1 having less than a good (graded as fair) clinical outcome. The Short Musculoskeletal Function Assessment Questionnaire scores (from 11 patients) were not significantly different from normal and were within the normal reported values for all indices and categories. There was no correlation between fracture fragment size and outcome. CONCLUSIONS: This study further supports the contention that a stable hip joint, as determined by EUA, after posterior wall acetabular fracture treated nonoperatively is predictive of continued joint congruity, an excellent radiographic outcome, and good-to-excellent early clinical and functional outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Ligamentous contributions to pelvic stability in a rotationally unstable open-book injury: a cadaver study.

INTRODUCTION: Due to the orientation of the sacroiliac joint (SIJ), as the symphysis widens in an open-book pelvic ring disruption, it should displace inferiorly. The purposes of this study were to reconfirm this inferior displacement and to evaluate the relative contributions of the pubic symphysis (PS), the sacrotuberous/sacrospinous ligament complex (STL/SSL) and the anterior sacroiliac ligament (ASIL) to pelvic ring stability in a rotationally unstable open-book injury. METHODS: For each of 6 cadaver pelves, the right hemipelvis was fixed to a table and the PS was sectioned. Under fluoroscopy, a manual external rotational force was then applied through the unfixed, left ilium. At the point of maximal displacement, a permanent AP image was obtained. With magnification corrected, horizontal (H) and vertical (V) displacements were measured. The pelves were then divided into two groups of three each. In Group 1, the PS release was followed by sectioning of the STL/SSL, and then the ASIL. In Group 2, the PS release was followed by sectioning of the ASIL and then the STL/SSL. The above described technique of manual manipulation and radiographic measurement was repeated after each stage of ligament release. RESULTS: The displacement after initial PS sectioning was not significantly different when comparing Group 1 to Group 2. In both groups, a significant and progressive increase in displacement was noted when the PS (H and V; p<0.05) and ASIL (H and V; p<0.05) were sectioned. However, there was no significant change with SSL/STL sectioning in either group. Vertical displacements were all directed inferiorly. CONCLUSIONS: The PS and ASIL are important in maintaining pelvic ring external rotational stability. However, the SSL/STL has little, if any, effect in this regard. Due to the orientation of the SIJ, external rotation of the hemipelvis, as in open-book injury, will show inferior vertical, as well as horizontal, displacement on the AP radiograph, despite the PSIL being intact.