Restoring the anatomical structure and biomechanical stability of the pelvic ring, promoting early functional exercise, and accelerating bone healing are all important goals of surgical treatment of pelvic ring injuries. Studies have shown that 40% of pelvic stability is maintained by the anterior complex(13). In a prior study, Liu et al. indicated that the stability of the posterior pelvic ring correspondingly increases with an increase in the stability of the anterior pelvic ring(14). However, information regarding the role of the inferior ramus of the pubis-ischium as a stabilizer of the anterior pelvic ring is limited, and it is unclear whether repair of the inferior ramus of the pubis-ischium is beneficial. Furthermore, repair of the inferior ramus of the pubis-ischium ramus injury has not received adequate clinical attention. Therefore, this study was conducted to address the gap in scientific knowledge regarding the biomechanical capabilities of new techniques for treating injuries to the inferior ramus of the pubis-ischium ramus.
Studies have shown that patients with pelvic fracture displacement of < 1 cm have a good prognosis(15, 16). Our results showed that when both the superior ramus and inferior ramus of the pubis-ischium ramus were fixed, the displacement of the posterior pelvic ring joint and the fracture of the anterior pelvic ring was less than 0.2 cm under loads of 500 N. These findings demonstrate that the superior ramus combined with the inferior ramus of the pubis-ischium ramus fixation can provide excellent biomechanical stability against anterior pelvic injuries. The biomechanical findings of this study indicate that repair and fixation of obturator ring injuries should be considered in clinical practice. The displacement of the posterior pelvic ring did not exhibit any statistically significant difference regardless of the fixation method employed for the anterior pelvic ring in this study, suggesting that fixation of the inferior ramus of the pubis-ischium ramus alone may be an alternative option for the treatment of Tile B pelvic injuries.
Internal fixation of the inferior ramus of the pubis-ischium ramus through the lateral approach to the perineum is a safe and easy technique with few related complications. In the present study, we applied the lateral-perineal approach to the ischial tuberosity, which was located 4 cm lateral to the apex of the pubic arch point; this approach has also been reported previously(17).
Surgical indications for the inferior ramus of the pubis-ischium ramus are controversial; in general, fractures of the inferior ramus of the pubis-ischium ramus are treated as benign fractures and are considered to have little effect on healing of the pelvic ring; therefore, proper reduction and fixation of the fracture are neglected, resulting in complications. Currently, complications are the dominant indication for surgical treatment(18). Persistent pain, sitting discomfort, lower limb discrepancies, and sexual dysfunction are all common complaints(18–21).Furthermore, symptomatic nonunion or malunion of the inferior ramus of the pubis-ischium has aroused clinical concern(21–25). Surgical treatment of the inferior ramus of the pubis-ischium ramus nonunion often requires bone grafting(19, 21),which is associated with an increased degree of medical trauma compared to initial fixation. Sexual dysfunction is a long-term complication of pelvic ring fractures that is often underestimated and unaddressed, resulting in feelings of shame and depression and reduced quality of life in patients(26, 27).According to a review, the incidence of sexual dysfunction after pelvic fractures varies from 10.3–100%(28–30). Several studies have shown that sexual dysfunction after pelvic fracture is related to multiple factors, including patient age, pelvic injury type, injury severity score, urethral injury, and pelvic floor soft tissue injury(10, 26, 31, 32).Further investigation has indicated that sexual dysfunction is associated with pubic branch fractures and pubic symphysis injuries(28). Nevertheless, whether repair of the inferior ramus in pubis-ischium ramus fractures has a positive effect on sexual function remains unelucidated. With an increasing understanding of the anatomy, biomechanics, and surgical techniques of pelvic injury, patients may benefit from recent efforts to prevent complications in the acute phase of fracture. In the present study, none of the patients experienced bone nonunion or malunion, and a low incidence (15.4%) of sexual dysfunction was observed, which may be related to the good reduction in the inferior ramus of the pubis-ischium ramus fractures.
Enhanced recovery after surgery (ERAS) is important in the management of pelvic ring injuries. In our clinical study, repair and internal fixation of the obturator ring increased the steadiness of the pelvic ring and met the requirements of early weight-bearing exercises. During recovery, the patient’s ability to sit on a wheelchair, walk with crutches, and even have sexual intercourse was improved; therefore, repair and fixation of the inferior ramus of pubis-ischium ramus fractures should be given more attention and recommended for traumatic pelvic ring injuries, even in anterior ring fractures that occur during hip replacement surgery. Impressively, following total hip arthroplasty, minimal displacement of the inferior ramus of pubis-ischium ramus fractures and significantly displaced acetabular fractures were observed; prosthesis loosening, fracture fixation, and hip revision surgery were eventually performed(33, 34). We assumed that revision surgery could be avoided if the inferior ramus of the pubis-ischium ramus fracture is repaired with non-weight-bearing exercises. However, this hypothesis needs to be confirmed by future studies.
Our study provides a foundation to promote the repair of the inferior ramus of the pubis-ischium ramus in patients with pelvic fractures. Further, our study is the first to report the biomechanical stability of the inferior ramus of the pubis-ischium ramus, and our results showed increased stability of the pelvic ring when the superior and inferior rami of the pubis-ischium ramus were fixed. Nevertheless, this study has several limitations. First, the biomechanical tests were performed on a limited number of samples. Furthermore, the specimens were not fresh, and the mechanical properties of the pelvis varied after formalin immersion. These limitations may have impeded the reliability of our results. However, the limited number of available cadaver specimens makes it difficult to perform tests on large samples. To solve this problem, prior researchers conducted multiple longitudinal load biomechanical tests using a single pelvic specimen(7). Therefore, multiple groups of loading tests were conducted on the same specimen in the present study. In addition, the loss of normal physiological function of the muscle tissue in the specimens affected the data. Individuals with obesity experience loads of > 500 N in the pelvis; therefore, further investigations with additional loading tests are required. Finally, we performed measurements using a Vernier caliper, which may yield inaccurate results; using a three-dimensional motion tracker, with characteristics of objectivity and high accuracy(5), would provide precise measurement data.