Simultaneous Bilateral Quadriceps Tendon Rupture in a Patient with Diffuse Idiopathic Skeletal Hyperostosis after Minimal Trauma: Eight-Year Follow-Up

Introduction The purpose of this report was to describe a very rare case of simultaneous bilateral quadriceps tendon rupture seen in a patient who was diagnosed as having diffuse idiopathic skeletal hyperostosis. Case Presentation A man aged 64 years presented to the emergency department with bilateral quadriceps tendon rupture. Surgical repair was performed with suture anchors and a stainless steel cable. His legs were immobilized in casts for six weeks. After removal of the casts, physiotherapy was started. Four months after surgery, he was able to walk with 0°–120° range of motion and active extension. He was followed up for 8 years without rerupture or other complications. Conclusion Bilateral rupture of the quadriceps tendon is a rare condition and generally related to metabolic disorders. Diffuse idiopathic skeletal hyperostosis is a metabolic disorder that causes bilateral quadriceps tendon rupture, and it accounted for the differential diagnosis of the underlying condition.


Introduction
In routine orthopedic practice, quadriceps tendon rupture is a common injury after major trauma in young patients. However, some metabolic disorders can cause spontaneous quadriceps tendon ruptures after minimal trauma. is extremely rare condition has been published in the literature with systemic diseases such as chronic renal failure, diabetes mellitus, rheumatoid arthritis, chronic tendinopathy, amyloidosis, and long-term use of systemic or local corticosteroid injections [1][2][3]. e purpose of this report was to describe a very rare case of simultaneous bilateral quadriceps tendon rupture in a patient who was diagnosed as having di use idiopathic skeletal hyperostosis (DISH).

Case
In 2008, a man aged 64 years was admitted to the emergency department with symptoms of pain and swelling in both knees and inability to walk. e history of the present condition was a fall from one step with minimal trauma.
Physical examination revealed tenderness and a gap in both suprapatellar regions, no active motion in the extensor mechanism, and palpable defects in the quadriceps tendons with respect to attachment to the patella. ere was only back pain in his medical history, which was treated with NSAIDs for ten years. ere was no history of steroid use, uoroquinolone antibiotic use, steroid injection, or chronic life-threatening disease. Initial X-rays were obtained. ere was an osteophyte in the tibial tuberosity in the lateral left knee X-rays. Magnetic resonance imaging (MRI) was performed for further imaging. MRI showed the bilateral total rupture of the quadriceps tendons and showed the osteophyte in the tibial tuberosity in the left knee ( Figure 1). A complete analysis revealed ossi cation and calci cation of the anterior vertebral column in the spinal X-rays ( Figure 2). Laboratory tests were normal and showed a total leukocyte count (WBC) of 8600/mm 3 , an erythrocyte sedimentation rate (ESR) of 13 mm/h, and C-reactive protein (CRP) of 1.8 mg/l. Renal function was normal with creatinine (Cr) of 1.3 mg/dl and blood urea nitrogen (BUN) of 19 mg/dl. e patient's blood pressure was normal and blood sugar level was also normal (glucose: 83 mg/dl). HBA1C was not known. Cholesterol levels were normal (HDL: 57 mg/dl; LDL: 126 mg/dl). e patient has no metabolic syndrome.
BMI was detected to be 24. e patient consulted the rheumatology department, and di use idiopathic skeletal hyperostosis was diagnosed when clinical and radiologic data were analyzed.   routine cleaning and draping, and a tourniquet was applied.

Surgery and Follow-Up
Longitudinal skin incisions were used for both knees. e distal ends of the quadriceps tendons were explored. e levels of the ruptures were very close to the patella. ere were not enough tendons at the patellar side to repair end to end. e intraoperative ndings were total rupture of the quadriceps tendons at the patella insertion. We observed in the calci cation inside of the tendon especially in the distal side of the ruptured tendon perioperatively. It could be related to DISH. Two 3.5 mm suture anchors were placed at the proximal pole of the patella for both sides, and the distal part of the tendon was reattached using Krakow's method. Subsequently, a cerclage wire was passed around the patella and the proximal part of the quadriceps tendon to reinforce xation ( Figure 3). e knees were immobilized in the knee casts for six weeks. e patient was able to walk after 3 weeks with cast. After cast removal, physiotherapy was started. e patient had 0°-120°pain-free range of motion in both knees 4 months after surgery with active extension. He could return to his job at the end of four months postoperatively. ere were no complications, wound infections, or joint limitations at the follow-up visits. At the last follow-up, eight years postoperatively, radiographs revealed broken wires, but the patient still had full range of motion in both knees with bilateral 15-degree extension lag (Figures 4 and 5). e Lysholm Knee Scoring Scale was applied to the patient, which showed 91 for the right knee and 95 for the left knee.

Discussion
DISH is characterized by ossi cation of the tendon, fascia, and ligaments. e vertebra is the most common site; pelvis, patellae, calcaneus, and olecranon can also be involved. e disease typically presents with ossi cation and the presence of owing syndesmophytes in the vertebral column and without degeneration of discs. e etiology remains unknown. Obesity, type 2 diabetes, hypertension, and vitamin A toxicity drew attention for their association with the pathology of DISH. Involvement of thoracic, lumbar, and cervical vertebra disease is 97%, 90%, and 78%, respectively. Involvement of the disease in the whole spinal column is seen in 70% of patients. Dysphagia related with esophageal compression, pain, sti ness, and limitation of motion in the vertebra are common complications of this disease. It is three times more common in males, and most patients are aged over 50 years. e most commonly used diagnostic criteria were de ned by Resnick and Niwayama [4]: (i) owing calci cations and ossi cations along the anterolateral aspect of at least 4 contiguous vertebral bodies, with or without osteophytes; (ii) preservation of intervertebral disk height in the involved areas and an absence of excessive disk disease; and (iii) the absence of bony ankylosis of facet joints and absence of sacroiliac erosion, sclerosis, or bony fusion, although narrowing and sclerosis of facet joints are acceptable [4]. Our patient has all the DISH criteria.
Quadriceps tendon rupture is a rare injury, but simultaneous bilateral quadriceps tendon rupture is exceptionally rare. ese are generally reported as case presentations in the literature. Chronic renal failure, systemic lupus erythematosus (SLE), rheumatoid arthritis, diabetes mellitus, gout, and long-term corticosteroid use can cause quadriceps tendon rupture [1,3,5]. e mechanism of the injury is a generally strong contraction of the quadriceps muscle while the knee is in semi exion and the ankle is in plantar exion [6]. Patients with quadriceps tendon rupture are not able to walk after the injury and tend to hold their knee in an extension position to relieve pain [1,6]. e physical examination generally consists of pain, inability of active extension of the knee, and a gap over the tendon. e suprapatellar gap is a pathognomonic sign for quadriceps tendon rupture [6]. In our case, there was no history of local or systemic corticosteroid use. Additionally, no joint or tendon pathologies had been reported before this injury. However, DISH was thought to be related to rupture of the quadriceps tendons in our patient, who had no other speci c cause, based on the history and laboratory results. However, DISH is not limited to the spinal column and has often been reported to involve peripheral sites. Mader et al. described extra spinal diagnostic features of DISH as (i) involvement of joints usually una ected by primary osteoarthritis; (ii) increased hypertrophic changes compared with primary osteoarthritis; (iii) prominent enthesopathies at various sites adjacent to peripheral joints; and (iv) calci cation and ossi cation of entheses in sites other than joints [7]. As a characteristic feature of patients with DISH, spur formation can cause tendon problems and rupture. Ellanti et al. found that patellar bone spurs had signi cantly higher incidence in their series of quadriceps tendon rupture [8]. Hardy et al. analyzed the presence of patellar spurs in patients with patellar tendon rupture, patella fracture, and quadriceps tendon rupture. e authors showed that 23 of 29 (79%) patients had patella spurs in the quadriceps tendon rupture group [9]. e pathophysiologic mechanism of quadriceps tendon rupture in patients with DISH could be multifactorial. However, blood supply of the quadriceps tendon, microtrauma, collagen quality, and tendon calci cations have a role in quadriceps tendon rupture [10]. Polymorphism of the collagen gene is another rare risk factor for spontaneous ruptures.
Chronic renal failure is another cause of simultaneous bilateral quadriceps tendon rupture in the literature. Lee et al. [5] reported a case of simultaneous bilateral quadriceps tendon rupture in a patient aged 30 years with chronic renal failure and parathyroid adenoma. is patient was under hemodialysis treatment, and tendon rupture occurred spontaneously. In this situation, uremic toxins, beta 2-microglobulin, come together in tendons. e other way in patients with chronic renal failure is a calcium, phosphate, and parathyroid mechanism, which can cause tendon rupture. Glomerular ltration failure reduces serum calcium in this condition, parathyroid hormone elevates, and bone resorption begins [5]. It was found that duration of dialysis was a related mechanism of injury.
Some patients in the literature with arthritis or systemic lupus erythematosus had endothelial swelling and vascular mononuclear cell in ltration of the tendon area in microscopy studies. Patients with rheumatoid arthritis have higher levels of collagenase, and this can cause tendon rupture. In addition, it was found that chronic symptomatic tendinopathy was also related to quadriceps tendon rupture in older patients.
is is the rst case report to demonstrate a possible relation between simultaneous bilateral quadriceps tendon rupture and di use idiopathic skeletal hyperostosis secondary to minimal trauma. is diagnosis should be taken into account in patients with quadriceps tendon rupture.

Conflicts of Interest
e authors declare that they have no con icts of interest.