Case 1. A sixty-one-year-old woman with a medical history of hypertension, hypothyroidism, osteoporosis, and depression presented to our orthopaedic clinic with severe low-back pain that started after she got up from bed. The work-up revealed a sacral stress fracture, which was treated conservatively. One year later, she had another episode of localized low-back pain, and magnetic resonance imaging revealed a fracture of the fourth lumbar vertebra. Four years after the initial evaluation, she sustained a fall that resulted in a femoral neck fracture, which was treated by open reduction and internal fixation. The following year, osteonecrosis of the left femoral head with secondary degenerative arthritis developed, and the patient underwent total hip arthroplasty with use of a cementless acetabular component and a cemented femoral component. Six months after the total hip arthroplasty, she presented with severe left-sided groin pain that occurred during weight-bearing. There was no history of trauma. Radiographs of the pelvis revealed an insufficiency fracture in the left superior pubic ramus. She was treated with partial weight-bearing, and the pain resolved within two months.
Case 2. A seventy-year-old woman presented with a medical history of coronary artery disease, scoliosis, renal impairment, and long-standing osteoarthritis of both hips. She underwent bilateral total hip arthroplasty with use of cementless acetabular components and cemented femoral components, with the procedures staged two years apart. Four months after the right total hip arthroplasty, she presented with severe right-sided groin pain that radiated to the thigh (
Figs. 1-A, 1-B, and 1-C ). No history of trauma was reported. Radiographs revealed superior and inferior pubic ramus fractures on the right. Within eight months after the onset of pain, the patient was symptom-free and radiographs showed that the fractures had healed.
Case 3. A sixty-year-old woman presented with a history of alcohol abuse that had resulted in cirrhosis of the liver, requiring liver transplantation and long-term immunosuppressive therapy. Three years later, she presented with pain in the right hip and had radiographic evidence of advanced osteoarthritis secondary to acetabular osteonecrosis. A right total hip arthroplasty was performed with use of a cementless acetabular component and a cemented femoral component, and the patient had an uncomplicated postoperative course. One year later, she presented with right-sided groin pain, particularly when weight-bearing. Radiographs demonstrated no fracture, and she was treated with oral analgesics and protected weight-bearing. The presumptive diagnosis was a pubic ramus insufficiency fracture, and the radiographs made at the two-month follow-up visit revealed callus formation around the right superior pubic ramus. The pain resolved within ten months.
Case 4. A fifty-eight-year-old woman presented with pain in both hips that interfered with her activities of daily living and that was not responsive to conservative measures. The medical history revealed a diagnosis of osteoporosis as well as osteoarthritis of the hips. The patient underwent bilateral total hip arthroplasty with use of cementless acetabular components and cemented femoral components, with the procedures staged twelve weeks apart. There were no postoperative complications. Four weeks after the second (right) arthroplasty, she experienced pain in the left buttock that radiated distally into the thigh. There was no history of trauma. Muscle relaxants, oral analgesics, and partial weight-bearing were prescribed. During the next two months, the pain resolved. Postoperative radiographs made at the six-month follow-up visit demonstrated callus formation around the left superior and inferior pubic rami.
Case 5. A forty-eight-year-old woman presented with disabling pain in both hips. Evaluation revealed a history of bilateral developmental dysplasia of the hip with secondary osteonecrosis and degenerative arthritis. Cementless total hip arthroplasty was performed bilaterally, with the procedures done six weeks apart, and was associated with an uncomplicated postoperative course. Seven months after the left total hip arthroplasty, the patient presented with left-sided groin pain. Radiographs demonstrated left superior and inferior pubic ramus insufficiency fractures with callus formation. She was treated conservatively with a cane and within four months was asymptomatic and able to return to full activity without support. Radiographs showed complete healing of the fractures without evidence of component loosening.
Case 6. A fifty-eight-year-old woman who was receiving chronic immunosuppressive therapy for seropositive rheumatoid arthritis presented with progressive bilateral acetabular protrusio. Over the course of several years, the patient underwent staged bilateral hip arthroplasty, with use of cementless acetabular components and cemented femoral components, and bilateral total knee replacement. Three years following the right total hip arthroplasty, severe right-sided groin pain developed. Radiographs showed evidence of a right superior ramus fracture. The fracture healed with partial weight-bearing. Radiographs made eight years later demonstrated complete healing of the fracture with evidence of bone remodeling.
A number of factors predispose patients to the development of insufficiency fractures, including diseases of bone and joints, nutritional deficiencies, radiation exposure, steroid use, and neurologic disease. Most pelvic insufficiency fractures occur in women, particularly those with osteoporotic bone who are semi-sedentary. Typically, patients who have severe osteoarthritis of the hip have limited activity levels before they proceed with a total hip arthroplasty. Then, following surgery, many of these patients are free of pain and resume activity at a much higher level than preoperatively. Thus, they are susceptible to the development of an insufficiency fracture if the bone quality is poor.
With the exception of one patient (Case 5), all of the fractures in this series occurred in women more than fifty-seven years of age who had comorbidities that predisposed them to osteopenic bone (i.e., rheumatoid arthritis, steroid use, or osteoporosis with previous fractures at other sites). In addition, in all but one patient (Case 6), the fracture occurred within a year after hip replacement. In previous case reports of pubic ramus insufficiency fractures, the fractures occurred in association with cemented acetabular components
2-7 , whereas each of the fractures in our series followed implantation of a cementless acetabular component. We can only speculate that cementless acetabular fixation and its attendant stress relief of the surrounding pelvic bones may render patients who have osteopenic bone more susceptible to insufficiency fractures. Mechanical and autopsy retrieval studies have predicted medial stress relief of surrounding bone when cementless acetabular components are used
8,9 . Insufficiency fractures should be differentiated from acute fractures, which occur early in the postoperative period as a result of press-fit insertion of cementless acetabular components in osteopenic bone
10 .
The physician should consider the possibility of a pubic ramus insufficiency fracture in patients with osteopenia who have returned to normal activity following total hip replacement and then present with groin pain, particularly if pain is elicited during palpation of the area over the pubic rami. For female patients who have a history of osteopenia and who have positive physical findings, we recommend a conservative approach if the initial radiographs do not reveal a fracture. Although insufficiency fractures can be detected earlier on bone scans than they can on plain radiographs, bone scans are nonspecific and relatively costly. Therefore, we recommend making a repeat anteroposterior radiograph of the pelvis three to four weeks later. If a fracture is not seen but the pain persists, we then consider performing a bone scan and/or a laboratory work-up, particularly for infection. Computed tomography and magnetic resonance imaging are used if the prior work-up has failed to produce a diagnosis. In contrast, when a patient who has a history that is atypical for insufficiency fracture (e.g., a man without osteoporosis) presents with groin pain, we recommend a more aggressive approach, with earlier use of bone-scanning, computed tomography, and magnetic resonance imaging.
A discerning history and physical examination combined with a conservative diagnostic approach may eliminate costly work-ups in search of other sources of pelvic pain. Once a pelvic insufficiency fracture is diagnosed, conservative management is the norm. In general, these fractures heal with partial weight-bearing, and patients return to their prefracture activity level within two to three months without recurrence of the fracture.