Surgical management of severely displaced IPRF: operative technique, indications, and preliminary clinical outcomes

Abstract

Background

Standardized surgical protocols for severely displaced inferior pubic ramus fractures (IPRF) remain scarcely reported. This study presents the operative technique and preliminary clinical outcomes of open reduction and internal fixation (ORIF) via the trans-inferior pubic ramus approach.

Methods

This retrospective case series included 6 patients with severely displaced IPRF (fracture separation ≥ 1.5 cm) treated with ORIF between 2016 and 2022. Fractures were categorized using a 3-zone anatomical system, Type I/II morphological typing, and conventional Tile/AO classifications to guide implant selection. Fracture union was confirmed by pelvic radiographs and CT, and functional outcomes were assessed using the 1-year Majeed Pelvic Score (MPS).

Results

The cohort comprised 4 males and 2 females (mean age 48.3 ± 13.4 years; mean follow-up 15.5 ± 3.2 months). Five fractures involved Zones II and III, and one extended across all three zones; 4 were Type I simple fractures and 2 Type II comminuted fractures, including 3 Tile/AO A2.2 and 3 Tile B injuries. Mean fracture displacement was 3.1 ± 0.9 cm. Mean operative time was 48.3 ± 17.2 min, with a mean intraoperative blood loss of 53.3 ± 25.0 mL; half of the patients underwent second-stage supplementary fixation. All fractures achieved bony union within 3–6 months. Five patients had excellent MPS (100 points), and one had fair function (65 points). No major perioperative complications occurred.

Conclusion

Severely displaced IPRF requiring surgery is rare, accounting for the small 6-case sample. The trans-inferior pubic ramus approach achieves low perioperative morbidity, reliable union, and satisfactory short-term function for operatively indicated cases. The 1.5 cm displacement threshold serves as an exploratory reference and requires prospective validation. All conclusions are limited by the small sample and warrant verification in large multicenter studies.

Background

The ischiopubic arch, formed by the ischial and inferior pubic rami, reinforces the pelvic load-bearing structure and supports sitting function. Most inferior pubic ramus fractures (IPRF) present with mild displacement and are managed conservatively. Existing surgical reports mainly cover chronic conditions including pelvic malunion [1], symptomatic IPRF nonunion [2], and ischial tuberosity avulsion fractures in young patients [3, 4], while dedicated operative management for acute severely displaced IPRF remains scarcely reported.

Severely displaced IPRF mostly occur with other pelvic ring injuries and are often unrecognized during initial fracture fixation. Disrupted ischiopubic arch integrity and soft tissue or skin irritation from sharp bony spicules constitute relative surgical indications. This study describes the operative technique and preliminary clinical outcomes of six cases, and discusses indications, exposure, fixation strategies and key intraoperative precautions.

Methods

Study population

This retrospective study enrolled 6 patients with severely displaced IPRF treated with pelvic ORIF at the Pelvic and Acetabular Surgery Department between January 2016 and December 2022. The cohort included 4 males and 2 females. The study was approved by the first author’ Institutional Review Board (Approval No. 2023KYKY2248). All patients provided written informed consent for retrospective analysis of de-identified clinical data, complying with the Declaration of Helsinki.

Inclusion criteria: IPRF combined with pelvic ring injuries, with maximum fracture separation ≥ 1.5 cm and sharp bone fragments posing irritation risks to surrounding soft tissues, neurovascular bundles and skin. Exclusion criteria: IPRF with displacement < 1.5 cm; patients who refused surgical treatment.

Surgical intervention

All operations were performed by a single senior pelvic and acetabular surgeon via the trans-inferior pubic ramus approach [5]. Routine preoperative preparation included perineal skin preparation and indwelling urethral catheterization. Patients were placed in a half-lithotomy position with hip flexion and abduction, and antibacterial films were used to isolate the perineum and urethra from the operative field.

An oblique incision was designed along the inferior pubic ramus with slight outward and downward curvature. The spermatic cord was identified at the superomedial incision margin to avoid iatrogenic injury. In female patients, the round ligament of the uterus was identified and protected at the superomedial margin of the incision. Subcutaneous dissection exposed the superior adductor space and the inferior border of the gluteus maximus; the adductor complex was bluntly dissected and retracted posterolaterally. Medial dissection preserved the adductor muscles and obturator membrane to protect the obturator neurovascular bundle.

For Type I simple fractures, anatomical reduction followed by 3.5 mm lag screw fixation was the primary strategy. Type II comminuted fractures were preferentially stabilized with 2.4 mm microplate osteosynthesis. Final implant selection was individualized based on fracture zoning, bone quality, concomitant ischial ramus fracture, intraoperative findings and surgeon judgment. Hardware was positioned to avoid protrusion on the ischiopubic bone surface. The urethral catheter was retained for 1 week postoperatively, and waterproof tape isolated the incision from the urethra during dressing changes. Cadaveric biomechanical evidence supports plate fixation for combined pubic-ischial ramus injuries to improve pelvic mechanical stability (Fig. 1).

Fig. 1.

Schematic diagrams and intraoperative photos of trans-inferior pubic ramus surgical approach. A, B: Incision marking and exposure of left inferior pubic ramus (male pelvis); arrow = spermatic cord, arrowhead = inferior pubic ramus. C: intraoperative body position and planned incision. D: postoperative wound closure

Parameter measurement

Preoperative maximum fracture separation was measured on multiplanar reconstructed two-dimensional CT images via the hospital PACS system [6]. Two senior orthopedic surgeons performed all measurements independently; discrepancies were resolved by consensus review, and the mean value was used for statistical analysis.

Fracture classification

We borrowed the anatomical zoning concept from the Nakatani classification designed for superior pubic ramus fractures, and divided all IPRF into three distinct anatomical zones (Fig. 2). Morphological typing was supplemented for surgical guidance: Type I referred to simple IPRF with displacement ≥ 1.5 cm and intact or sharp bone fragments; Type II represented comminuted IPRF with fragmented bone mass. All cases received comprehensive pelvic fracture classification following Tile’s system [7] and the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) compendium [8] based on preoperative X-ray and CT scans.

Fig. 2.

3D-CT anatomical diagram of three-zone classification for IPRF. Zone I: medial to obturator foramen (parasymphyseal segment); Zone II: below obturator foramen (adjacent to pudendal neurovascular bundle); Zone III: lateral to obturator foramen (ischiopubic junction near the acetabulum)

Postoperative rehabilitation protocol

As most IPRF are combined with other pelvic injuries, individualized rehabilitation plans were formulated according to specific fracture patterns.

Injuries limited to the inferior and ischial rami: Active/resisted hip adduction was forbidden within 2 weeks postoperatively; knee flexion was restricted to < 70°, and excessive hip rotation or wide-range motion was avoided. Direct weight-bearing sitting on the affected ischiopubic region was prohibited. Combined symphyseal diastasis or sacroiliac joint separation treated with fixation: Partial weight-bearing ambulation with crutches started at postoperative week 4, progressing to full weight-bearing within 6–8 weeks. Combined acetabular fractures: Partial weight-bearing was delayed until 6–8 weeks postoperatively. All patients completed at least 12 months of standardized follow-up to evaluate fracture union and functional recovery.

Radiological assessment of fracture union

Fracture union was judged by combined radiological and clinical indicators, independently evaluated by two senior orthopedic surgeons; disagreements were resolved by group discussion.

Serial pelvic anteroposterior radiographs were obtained at 6 weeks, 3 months, 6 months and 12 months postoperatively. Supplementary 2D-CT via PACS was arranged for cases with ambiguous plain film findings to confirm cortical continuity and bridging callus. Radiological union was defined as continuous trabecular bone or bridging callus across the fracture gap, blurring of the fracture line, and absence of progressive radiolucent zones or hardware loosening. Clinical union was confirmed by absence of local tenderness over the inferior pubic ramus, pain-free sitting and partial weight-bearing, and no abnormal mobility at the fracture site.

Functional assessment

One-year postoperative functional outcomes were retrospectively collected at outpatient follow-up using the validated Majeed Pelvic Score (MPS). The scale covers five dimensions: pain (30 points), walking and standing function (36 points), sitting tolerance (10 points), work status (20 points), sexual function (4 points). Functional grading standards were defined as excellent (≥ 85), good (70–84), fair (55–69), and poor (< 55) [9].

Results

Baseline demographic, trauma and radiographic data of all patients are summarized in Table 1. The cohort included 4 males and 2 females, with a mean age of 48.3 ± 13.4 years (range 24–63 years). Mean follow-up was 15.5 ± 3.2 months (median 14.5 months, range 12–21 months). Five injuries were caused by traffic accidents, and one by a fall from height, with various combined pelvic ring injuries across cases.

Table 1.

Baseline demographic and clinical characteristics of included patients

Cases	Gender	Age (years)	Affected side	Cause of injury	Concomitant injuries	Morphological type (Type I/II)	Tile classification	AO/OTA classification
Case 1	Male	46	Left	Traffic accident	Ipsilateral superior pubic ramus fracture, sacroiliac joint diastasis, acetabular fracture	I	B1.2	B1.2
Case 2	Male	51	Left	Traffic accident	Ipsilateral acetabular fracture, ischial ramus fracture and contralateral anterior acetabular wall fracture	II	A2.2	A2.2
Case 3	Female	57	Right	Traffic accident	Ipsilateral superior pubic ramus fracture, acetabular fracture, pubic symphyseal diastasis, iliac fracture and sacroiliac joint diastasis	I	B1.2	B1.2
Case 4	Male	24	Left	Height fall	Ipsilateral superior pubic ramus fracture and sacroiliac joint diastasis	I	B1.2	B1.2
Case 5	Male	49	Right	Traffic accident	Ipsilateral ischial ramus fracture	II	A2.2	A2.2
Case 6	Female	63	Right	Traffic accident	Ipsilateral ischial ramus fracture and superior pubic ramus fracture	I	A2.2	A2.2

All Tile and AO/OTA classifications conform to official diagnostic criteria for pelvic ring stability. The proposed morphological stratification is for clinical decision-making reference only and does not modify the official subtype hierarchy of either classification system

Per the three-zone system, only Case 3 involved all three zones, while the remaining five fractures were confined to Zones II and III. Four fractures (66.7%) were Type I simple pattern, and two (33.3%) were Type II comminuted. Pelvic ring classification identified 3 Tile/AO A2.2 cases and 3 Tile B1.2 anteroposterior compression injuries. Maximum fracture displacement ranged from 2.2 cm to 4.1 cm, with a mean of 3.1 ± 0.9 cm (Table 2).

Table 2.

Perioperative parameters and 1-year functional outcomes

Cases	Second-stage surgery performed (yes/no)	Second-stage surgery interval (d)	Time from injury to surgery (d)	Operative time (min)	Intraoperative blood loss (mL)	Internal fixation	Complications	Maximum fracture displacement (cm)	MPS total scores	MPS functional grade
Case 1	Yes	7	26	30	30	1 Lag screw	No	4.1	100	Excellent
Case 2	Yes	6	15	50	60	1 Microplate	Gluteal pain*	2.2	65	Fair
Case 3	Yes	5	23	40	40	1 lag screw	No	2.4	100	Excellent
Case 4	No	–	5	50	50	1 Microplate	No	3.5	100	Excellent
Case 5	No	–	10	40	40	3 Lag screws	No	2.3	100	Excellent
Case 6	No	–	11	80	100	1 Lag screw + 1 microplate	No	4.0	100	Excellent

MPS, majeed pelvic score. ^*Resolved completely after implant removal at 1-year follow-up

Perioperative indicators are detailed in Table 2. The mean interval from trauma to surgery was 15 ± 8.1 days (range 5–26 days). Three patients (50%) underwent second-stage surgery, as severe IPRF displacement was not recognized during initial pelvic fracture fixation. Mean operative time was 48.3 ± 17.2 min (range 30–80 min), with a mean intraoperative blood loss of 53.3 ± 25.0 mL (range 30–100 mL). No bone grafting was performed. Implant schemes were individualized, including single lag screws, microplates, cannulated lag screws and combined screw-plate constructs (Table 2, Figs. 3 and 4).

Fig. 3.

Representative case imaging data. A: Preoperative 3D-CT of Case 3 (Type I right IPRF); B: postoperative image after single lag screw fixation. C: preoperative pelvic scan of Case 2 (Type II left comminuted IPRF combined with pelvic fracture); D: residual inferior ramus displacement after initial pelvic fixation; E: imaging after second-stage supplementary fixation with minor residual fracture gap; F: complete bone union at 5-month follow-up; buttock pain disappeared after implant removal at 1 year

Fig. 4.

Preoperative and postoperative imaging of 63-year-old female Case 6 with combined displaced right inferior and ischial ramus fractures treated with ORIF. A: Preoperative 3D-CT reconstruction showing dual ramus displacement. B: immediate postoperative pelvic AP film showing microplate on inferior ramus and cannulated screw on ischial ramus. C: postoperative 3D-CT confirming satisfactory anatomical reduction and proper implant position. D: PRVR 3D annotated image displaying screw trajectory and microplate outline

All patients completed ≥ 12 months of follow-up, and radiographic bony union was confirmed at 3–6 months postoperatively. No surgical site infection, nonunion, neurovascular injury or sexual dysfunction occurred. Only Case 2 had persistent postoperative gluteal pain, which resolved completely after implant removal at 1 year (Table 2, Fig. 3).

One-year MPS results are shown in Table 2. Five patients achieved a full score of 100 (excellent recovery), with complete pain relief, independent full weight-bearing, unrestricted sitting and full return to pre-injury work. Case 2 obtained an MPS of 65 (fair outcome) with persistent moderate gluteal pain and single-cane ambulation, but returned to original work normally.

Discussion

The ischiopubic arch is the core weight-bearing bony structure for sitting. ORIF is indicated for severely displaced IPRF with soft tissue irritation, impaired sitting function, or risk of cutaneous penetration from sharp fracture fragments. Without surgical intervention, severe displacement disrupts pelvic gravity lines, induces abnormal gait and chronic lumbopelvic pain, and compromises long-term sitting function and quality of life [10].

Malunion and nonunion of pubic ramus fractures can cause hip pain, leg length discrepancy, visceral compression and sexual dysfunction secondary to pelvic ring malalignment [11, 12]. Oransky et al. reported that insufficient emergency fixation and inadequate reduction are primary contributors to pelvic post-traumatic malunion and nonunion, substantially increasing revision surgical difficulty [13]. Deficient primary pelvic fixation acts as the dominant risk factor for post-traumatic pelvic deformity and fracture nonunion [14]. Omitted emergency external fixation and incomplete fracture reduction complicate secondary pelvic reconstruction and elevate complication risks [15].

Long-term follow-up has confirmed that suboptimal reduction after external fixation inevitably leads to progressive late pelvic deformity [16, 17]. For anterior pelvic ring injuries, percutaneous screw fixation is a widely used minimally invasive option, but union rates and displacement patterns vary by fracture location and fixation quality [18]. Pelvic nonunion remains a persistent clinical challenge for trauma surgeons [19], and classic pelvic fracture frameworks have standardized therapeutic principles for anterior pelvic ring injuries [20]. Anterior pelvic ring pseudoarthrosis is easily overlooked during initial diagnosis, and delayed treatment often leads to persistent symptoms [21].

While surgical strategies for superior pubic ramus fractures have been widely documented, literature on primary inferior pubic/ischial ramus fixation remains scarce. Studies indicate that displaced IPRF are strongly associated with posterior pelvic ring injury, serving as a reliable indirect radiographic marker [22]. Open pelvic ring injuries with concomitant ramus fractures require more complex management protocols, but isolated closed IPRF follow different treatment principles [23].

Most IPRF result from low-energy trauma and heal spontaneously due to abundant cancellous bone perfusion [24, 25]. Classic acute pelvic fracture management principles also support conservative treatment for most minimally displaced ramus fractures [26]. Consequently, clinically significant displacement requiring surgical intervention is rarely reported; nonunion of isolated ramus fractures is uncommon but can cause persistent symptoms when it occurs [27].

Ischial tuberosity avulsion fractures typically occur in adolescents or athletes with immature bone due to forceful hamstring contraction [3]. In contrast, all IPRF in our cohort were components of complex pelvic fractures. In half of the cases, ≥ 1.5 cm residual displacement persisted after fixation of concomitant pelvic fractures, disrupting ischiopubic arch integrity and causing soft tissue irritation from bony spicules. Concurrent ipsilateral ischial ramus fractures are the primary etiology of persistent post-traumatic sitting discomfort and core surgical indications. Surgical decisions should rely on comprehensive evaluation of displacement, fracture morphology, soft tissue compromise risk and patient functional demands, rather than displacement alone.

The pudendal nerve runs along the medial cortex of the ischial and inferior pubic rami within Alcock’s canal [28]. Severe fracture displacement or bony spurs may entrap the nerve and induce traumatic pudendal nerve entrapment syndrome [29]. Approximately 25%–30% of pelvic fracture patients develop perineal and sexual dysfunction; female genitourinary and reproductive function can be adversely affected by pelvic ring malalignment [30], and male sexual dysfunction is also a recognized sequela of severe pelvic trauma [31]. Overall, 60%–80% of fracture-related pudendal nerve injuries achieve full or near-full recovery [32]. IPRF, pubic symphyseal diastasis and sacral fractures all increase entrapment risk, and surgical decompression is warranted for refractory symptoms. No sexual dysfunction was recorded in our cohort, which may be attributed to cultural reluctance to report related symptoms.

Most clinicians recommend surgical fixation for ischial tuberosity avulsion fractures with displacement > 1.5 cm, as this threshold significantly increases nonunion and delayed union risks. Meta-analyses have confirmed that operative treatment yields better functional outcomes for displaced adolescent pelvic avulsion fractures [33], and multiple clinical series support surgical intervention for significantly displaced ischial tuberosity avulsions in young athletes [34, 35]. Given the anatomical and biomechanical continuity of the ischiopubic arch, we extrapolated this 1.5 cm value as an exploratory clinical reference for severely displaced IPRF. No dedicated biomechanical or prospective trials have validated this threshold for IPRF; it remains an empirical cutoff extrapolated from analogous pelvic injuries.

We adopted the anatomical zoning logic of the Nakatani classification for superior pubic ramus fractures to construct a three-zone system for IPRF [36], facilitating preoperative neurovascular risk assessment and surgical planning. We further proposed Type I/II morphological stratification as an auxiliary tool for implant selection: this is a preliminary surgical stratification tool, not a formal modification of established AO/OTA and Tile classification systems, and requires further validation in larger cohorts. Simple Type I fractures are sufficiently stabilized by single lag screws, while comminuted Type II fractures require microplate fixation for rigid stability. Concurrent displaced ischial ramus fractures require additional cannulated lag screws, forming combined screw-plate constructs. Satisfactory reduction and fixation of the inferior pubic ramus generally yield favorable healing of associated ischial ramus fractures.

The trans-inferior pubic ramus approach with strict perineal sterilization reduces surgical site infection risk, and standardized subperiosteal dissection protects neurovascular structures. For patients with combined ischial ramus fractures, this approach also reduces heterotopic ossification risk, preserves gluteal muscle integrity, and avoids sciatic neurovascular injury and scar-mediated gluteal pain.

Three of six cases were Tile/AO A2.2 stable pelvic ring injuries. Current mainstream classifications prioritize posterior ring stability and lack stratification of A2.2 fractures by anterior ramus displacement severity. We propose auxiliary A2.2.1 (mild displacement, conservative management) and A2.2.2 (severe displacement, surgical consideration) stratification for clinical reference only, which does not modify formal classification systems and requires further validation. The 50% staged secondary surgery rate was attributed to insufficient initial imaging evaluation and intraoperative planning, reminding clinicians to strengthen comprehensive preoperative assessment to reduce reoperations.

This study has several limitations. First, the single-center retrospective design with only six patients limits generalizability; the 1.5 cm displacement threshold lacks exclusive biomechanical validation for IPRF. Second, the absence of a control group, and limited follow-up duration may introduce recall bias. Third, the proposed zoning and morphological stratification only serve as preliminary surgical aids without revising formal classification systems. Fourth, the single-surgeon design improves internal consistency but reduces external validity. Despite these limitations, this case series supplements rare clinical data on surgically treated severely displaced IPRF and introduces a reproducible low-morbidity surgical approach.

Conclusion

Severely displaced IPRF requiring surgical intervention is a rare clinical entity, accounting for the small six-case sample of this study. The trans-inferior pubic ramus approach achieves low perioperative morbidity for operatively indicated cases, with reliable bony union and satisfactory short-term functional recovery. Individualized fixation can be applied based on fracture morphology: lag screws for simple fractures, and microplates for comminuted injuries. The 1.5 cm displacement threshold serves only as an exploratory reference and awaits prospective validation in larger cohorts. All conclusions are constrained by the small sample, and multicenter large-scale prospective trials are required to verify the generalizability of this surgical protocol.

Abbreviations

3D-CT

Three-dimensional computed tomography

AO

Arbeitsgemeinschaft für osteosynthesefragen

OTA

Orthopaedic trauma association

CT

Computed tomography

IPRF

Inferior pubic ramus fracture

MPS

Majeed pelvic score

ORIF

Open reduction and internal fixation

PACS

Picture archiving and communication system

PRVR

Photorealistic volume-rendered

Funding

This work was supported by National Key Research and Development Program of China (Grant No.: 2023YFC3605005) and Hongkou District Key Clinical Specialty Construction Project (Grant No.: HKLCFC202407).

Data availability

All original Research data can be provided by corresponding author upon reasonable academic request.

Declarations

Conflict of interest

The authors declare no financial, commercial or personal competing interests.

Ethical approval

This retrospective study was approved by first author’ Hospital Institutional Review Board (Approval No. 2023KYKY2248). All patients provided written informed consent at admission to allow research use of de-identified clinical data, complying with the Declaration of Helsinki.

Consent for publication

All authors agree to publish this manuscript in current form.