The force vectors causing pelvic fractures have been well elucidated and correlate with fracture pattern.11 Fractures can be stable, rotationally unstable but vertically stable, or rotationally and vertically unstable. These varying patterns must be evaluated separately to assess their inherent differences. One would expect that the more unstable an injury is, the greater the accompanying soft tissue injury will be. With more disruption of the pelvic ring and ligaments, greater morbidity has been seen.1
This study critically evaluates the outcome of rotationally unstable but vertically stable pelvic ring injuries treated with open reduction and internal fixation.
MATERIALS AND METHODS
Twenty-nine patients with rotationally unstable but vertically stable pelvic ring disruptions treated by open reduction and internal fixation were studied. The 29 represent only those patients who had greater than 1 year of followup and who were available for a followup examination. The average followup was 39 months (range, 12-84 months).
All patients had their pelvic ring injuries treated operatively by the same surgeon (JMM). Patient data were obtained from inpatient and outpatient charts, initial radiographs, followup radiographs, a patient based questionnaire, and a followup physical examination.
There were 20 male and 9 female patients with an average age of 34 years (range, 15-65 years). Associated injuries included 12 acetabular fractures, 3 long bone fractures, 1 hip fracture, 3 knee injuries, 4 foot injuries, and 1 spinal injury. The anterior ring injury was a symphysis dislocation in 23, rami fractures in 2, and both in 4 patients (Table 1). Five patients had minimally displaced sacral fractures. The other patients had either anterior widening of the sacroiliac joints (12), an acetabular fracture (10), or both (2) (Table 1).
Preoperative and postoperative displacements were evaluated on the 3 standard views of the pelvis as previously described.8 The average preoperative displacement of the 27 symphysis dislocations was 35 mm (range, 10-90 mm). Rami fractures averaged 18 mm of displacement (range, 5-30 mm).
Reductions were all performed open through a Pfannenstiel or ilioinguinal approach depending on the associated pathology. Techniques for reduction were previously described.8 Fixation was obtained using curved 3.5-mm reconstruction plates (Synthes, Paoli, PA). A 6-hole plate was used for symphyseal fixation. Longer plates were used as needed for rami fractures. Postoperatively, patients were allowed immediate full weightbearing unless this was prevented by another injury (acetabulum).
A standard questionnaire to determine return to work, ambulation ability, neurologic sequelae, and pain during various activities (sitting, standing, walking, bending, lifting, and sexual activities) was used to evaluate patients. Physical examination was performed to evaluate muscle strength and tenderness.
Followup radiographs were graded for quality of reduction, failure of hardware, and loss of reduction.
Results are summarized in Table 2 for those patients who could be evaluated for each variable.
There were 22 excellent, 6 good, and 1 fair reduction according to previously described criteria.8 Four of the 6 good reductions were symphysis dislocations that had only 5 mm of separation postoperatively and were therefore less than 2 mm from being anatomically reduced.
Twenty-two (76%) patients were fully ambulatory, had no limp, did not need assistive devices, and had no restrictions. Six other patients had a mild limp or occasionally required an assistive device because of coincident injuries to the acetabulum (1), foot (3), and knee (2). Only 1 patient had a mild limp that may be related to his pelvic fracture. He had sustained a symphysis dislocation and complains of back pain with ambulation. Thus, of the 23 patients without extraneous reasons for ambulation problems, 22 (96%) had no restrictions.
Three patients were limited in their activities because of pain stemming from their acetabular fracture. Two patients had groin pain with moderate activities, and 1 with strenuous activity. None of the patients had pain referable to their pelvic injury at their current level of activity. Of the remaining 26 patients, 18 (69%) patients had no complaints of pain under any circumstances, including strenuous activities. Many of the patients returned to high level recreational athletics. Six patients complained of pain only with very strenuous activities, and 1 patient complained of pain only with horseback riding. Only 1 patient complained of pain with normal daily activities. His discomfort is in his back and occurs after standing for more than 2 hours or when lifting. No patient had any other difficulty in activities of daily living, including sexual activities.
Twenty-four patients (83%) returned to work within 1 year. Twenty-two (75%) of them returned to their original jobs. The other 2 patients changed jobs because of injuries other than their pelvic injury. Four patients did not return to work. Two patients retired, 1 because of his age and the other because of a foot injury. One patient is in drug rehabilitation, and 1 is unemployed for nonphysical reasons. Thus, only 1 patient did not return to work because of his pelvic injury (3%). He is the same patient who has significant back pain.
Twenty-eight patients had manual muscle testing performed during their followup visit (1 patient had his hip fused). Twenty-five of the 28 (89%) had 5/5 strength in both lower extremities. Two patients have a foot drop secondary to acetabular fractures and normal strength in all other distributions. The final patient has normal strength except for hip abduction (4/5) on the side of an acetabular fracture.
Followup Radiographic Evaluation
Twenty-three (79%) patients had no change in their most recent radiograph when compared with the immediate postoperative films. In 4 patients, the symphyseal plate broke. Three patients have a mild widening of their symphyseal space. Their spaces at most recent followup measure 7, 9, and 10 mm, respectively. One patient also has a broken plate. All 3 patients are working at their preinjury job. Two patients work with horses, 1 in the rodeo wrestling steers and the other in the film industry handling and training horses. The second patient's immediate postoperative radiographs showed irregularity in the symphyseal articulation that may indicate an old injury. None of the radiographic findings required reoperation and the patients did not have different outcomes than the group as a whole.
The emergent and definitive management of pelvic ring disruptions are controversial. Many methods of stabilization have been recommended. These include pelvic slings, external fixation, and open reduction with various forms of internal fixation.
External fixation closes down the pelvic volume and may be lifesaving during the acute resuscitation. The reduction obtained with these devices is rarely anatomic, however. Kellam1 considered an acceptable reduction of the anterior ring to be less than 2 cm displacement. Yet even using this less stringent criteria, external fixation alone resulted in only 80% acceptable reductions of rotationally unstable injuries. Eighty percent of the patients who did not obtain an acceptable reduction in Kellam's study group required analgesics.
Open reduction and internal fixation results in a higher percentage of anatomic reductions.4 Most surgeons fix the anterior ring with plates and screws.2,3,5,6,10 Single (2, 4, and 6 hole) and double plating techniques for the symphysis have been described. Lange and Hansen2 reviewed 6 patients treated with 2-hole plates and 7 treated with 4-hole compression plates. They found that acceptable reductions (average, 1.2 cm) were obtained in all cases. Two of the 4-hole plates were loose at followup as compared with none of the 2-hole plates. It was concluded that 2-hole plates are preferable. However, 1 of the 4-hole plates was in a patient who had a completely unstable posterior injury that was not fixed and the other 4-hole plate was in a patient who had an open fracture. Later Webb et al10 reported excellent results in 5 patients with rotationally unstable injuries treated with a 2-hole plate. There were no losses of reduction or plate loosening in any of the cases. However, the average time to full weightbearing in the patients was 57 days. These authors thought that a 2-hole plate would allow some of the normal rotational motion at the symphysis and relieve stress on the plate. However, the normal rotational motion at the symphysis has been measured at less than 1.5 ° in the transverse plane and less than 0.5 mm of rotational translation in males. Conversely, vertical translation was found to be close to 2 mm.9 This plane of motion is not well supported by a 2-hole plate meant to support the pelvis only in tension. It must be further understood that the measurements were made in healthy volunteers with the sacrospinous and sacrotuberous ligaments intact. After injury, these ligaments are often ruptured, further destabilizing the pelvis. Thus, to allow early weightbearing, a longer plate is preferable.
Using 4-hole dynamic plate fixation, Pohlemann et al4 reported 73 anatomic reductions (93%) and 5 reductions within 1 cm in rotationally unstable injuries. Twenty-five of 28 patients available for followup at 2.2 years did not complain of pain. Two (7%) had pain on strenuous exertion, and 1 (3.5%) had moderate pain. Twenty-one percent had some mild sensory deficit and none had sexual disturbance.
Despite the many treatment options available for the treatment of rotationally unstable but vertically stable pelvic fractures there is relatively little information available regarding the functional results of patients treated with open reduction and internal fixation of the anterior pelvic ring. This paper reports the functional outcome of 29 patients after open reduction and internal fixation of the anterior pelvic ring. The indication for surgery in this series was symphyseal disruption in 27 patients (4 also had rami fractures) and displaced rami fractures in combination with acetabular fractures in 2 patients.
Only 1 patient in the group has symptoms that affect his daily life. He sustained a sacral fracture and symphysis dislocation from a crush injury. His reduction was anatomic and was unchanged at final followup. He also sustained a knee injury for which he still wears a brace. His complaints are referable to his back. The area of his pain is not over his sacrum, but in the lumbar spine area. It is possible that this pain may be referred or caused by his sacral injury, and is graded as such. For the other patients that could be graded in each followup category, 96% had no pain or pain only on very strenuous activity; they ambulated without assistance or limitation and returned to work. Twenty-two of 26 patients who returned to work resumed their preinjury job. No patient had difficulty with sexual function.
On followup radiographic examination, 4 broken plates were found in the group. As previously described, 6-hole curved 3.5-mm reconstruction plates were generally used for symphyseal fixation. These plates undoubtedly eliminate some of the normal motion of the symphysis. This helps to avoid early plate failure while allowing immediate weightbearing. A 2-hole plate may not have the strength to withstand the coronal plane stresses caused by weightbearing. Late plate breakage in this group did not require reoperation and was not associated with a deterioration in the clinical result.
From this group of patients, it is concluded that open reduction and internal fixation of the anterior pelvic ring for rotationally unstable injuries has a high functional success rate. This treatment is recommended as described for these injuries.
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2. Lange RH, Hansen ST: Pelvic ring disruption with symphysis pubis diastasis. Clin Orthop 201:130-137, 1985.
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11. Young JWR, Burgess AR: Radiologic Management of Pelvic Ring Fractures. Baltimore, Urban and Schwarzenberg 1987.