Traumatic bilateral rupture of the patellar tendon in an apparently healthy patient

Introduction
The patellar tendon represents the connection between the patella and the anterior tubercle of the tibia. It is the most distal segment of the extensor apparatus of the knee that is composed of the quadriceps muscle and its tendon, the patella and the patellar tendon. Ruptures in the patellar tendon due to minimal trauma are characteristic for patients with degenerative conditions. These conditions can be systemic such as hyperparathyroidism, gout, lupus erythematosus, rheumatoid arthritis, patient receiving long-term dialysis or local - tenosynovitis, repeated local steroid injections. Taking into account the fact that the rupture of the patellar tendon in apparently healthy patients is rare, a bilateral simultaneous rupture represents an even rarest pathology; only around 20 such cases have been ever mentioned in literature. This case presentation is important not only due to the extreme rarity of the condition, but also due to the elected therapeutic solution.

Case presentation
In March 2008, a 37 year old male presents for consult in our emergency room with bilateral functional impotency in the lower limbs. The patient had suffered a fall from approximately 2.5 meters and at the moment of impact he performed a bilateral knee hyperflexion. His medical history revealed that he did not suffer from any chronic conditions and that he was not under a current medical treatment. Other than the lesions in the lower limbs, no other traumatic lesions were noted. Arterial pressure and pulse were within the range of normal. The rapport between his height and his weight revealed that he was obese (group 1).
Local clinical examination showed tumefaction and local pain bilaterally at knee level. Bilateral palpation revealed that apparently the patellas were integer, but presented a certain degree of ascension that was difficult to evaluate due to the tumefaction of the knee. Due to the pain, active or passive extension/flexion could not be performed. Distal to the traumatic lesion, blood flow and nerve integrity were unaltered.
The presumptive clinical diagnosis was bilateral rupture of patellar tendon. However, the differential diagnosis included contusion or strain of the knee, patellar fracture and quadriceps tendon rupture.
We performed a bilateral antero-posterior and lateral radiography (Fig. 1). The images showed the integrity of the patella and its bilateral ascension, suggestive for rupture of the patellar tendon. In order to confirm the diagnosis, bilateral echography was performed (Fig. 2).

Laboratory tests were performed as routine before surgery, but also in order to determine if the patient had any systemic conditions. All findings were normal.
The surgical approach was similar for both knees and was performed simultaneously by two teams. We performed spinal anesthesia because it represents the election anesthetic for lower limb surgery. We began with a median incision through the tegument and the subcutaneous cellular tissue; after identifying the patellar tendon, the two heads of the rupture zone were prepared. The tendinous heads were sutured with nonabsorbable sutures in U-shape. The knee was then gently positioned in 30 degrees flexion in order to test the mechanical quality of the suture. In this position, a Dall-Miles cable was inserted through the patella and the anterior tubercle of the tibia (Fig. 3).
After surgery, the patient received anticoagulation and antibiotic medicine, in conformity with our standard of care. Post operatory, the patient was immobilized in splints. After three days, recovery began by removing the splints during the day and performing flexion movements of the knee up to 30 degrees. After 45 days, with minimal incisions, the cables were removed and the patient was advised to perform progressive flexions for the next 45 days. Normal walking was obtained after 90 days, and after 120 days forceful physical activity (sport) was allowed.

Discussion
Bilateral rupture of the patellar tendon is rather uncommon. It is an injury associated either with sport either with systemic diseases; these can be either gained – such as diabetes, lupus, rheumatoid arthritis, tuberculosis, syphilis, osteomalacia, glomerulonephritis or congenital - Ehlers-Danlos disease. It is considered that these associated conditions lead to a weakening of the bone and cartilage system, thus increasing the risk of unusual tendon ruptures.
Literature reveals that bilateral rupture of the patellar ligament has also been associated with corticosteroid medication possibly because steroid drugs with topic usage lead to a decrease in collagen production in the area. This may be true, although most of the patients that have been diagnosed with this bilateral rupture and were using steroids were also suffering from a systemic disease such as lupus (1) or rheumatoid arthritis (2). Clark (3) reports a case of bilateral patellar tendon rupture in a patient (young male) with no systemic diseases that was undergoing repeated steroid injections into both patellar tendons (histology revealed local modifications induced by steroid usage). Kothari (4) presented a patient with bilateral simultaneous patellar tendon ruptures associated with osteogenesis imperfecta.
Another incriminated risk fracture for bilateral ruptures is represented by age. There are several case reports that describe these ruptures in patients over 60. Here, the main reason for the bilateral fractures consists in the loss of tissue elasticity, decreased tissue perfusion and degenerative changes in the collagen fibrils, thus leading to a higher risk of breaking. For example Van Glabbeek (5) reports the case of a 67-year-old man with bilateral rupture of the patellar tendon caused by minor trauma and Haasper (6) reports a 60-year-old female without an obvious trauma, systemic disease or medication who suffered a spontaneous bilateral patellar tendon rupture.
However, literature mentions around 20 cases (7, 8, 9, 10, 11, 12) in which the bilateral rupture due to trauma had no explanation – the patients were young, with no genetic disorders and no systemic diseases. Our patient experienced the rupture due to a fall that lead his knees into hyper flexion, thus causing a sudden and important contraction in the quadriceps muscle that might have lead to the rupture. It is important to also keep in mind the biomechanics of the knee joint – the pressure placed upon the knee increases progressively as the bones perform the flexion movement – maximum pressure is reached at a 90 degree angle.
In most of the reported cases (as in ours), the diagnosis was based upon anamnesis (a history of a fall), clinical exam (palpation) and conventional X-rays. We also performed an ultrasound of the affected area, in order to receive better confirmation. In literature, the successful use of MRI in order to obtain other details, such as tendon abnormalities, was reported.
Whereas treatment is concerned, literature reports a good outcome of the patients after surgery. There are some possibilities for the surgical repair of the patellar tendon: simple end-to-end tendon suture, arthroscopic reconstruction of a ruptured patellar tendon, repair of patellar tendon rupture with suture anchors, sutures passed through drill holes, sutures secured through parallel vertical holes drilled in patella and transverse hole drilled in tubercle of the tibia or tendon reattached to the tubercle of the tibia by a screw with a nylon washer. The most used technique consists in a non absorbable suture reinforced with anchors fixed to each patella. Quintero Quesada (10) considers that besides the described technique, a quadriceps tendon flap is also a necessity, especially in case of pathological tendinous tissue. In a case report concerning a 9-year-old child, Muratli (13) has used a treatment with primary end-to-end repair, reinforcement with cerclage wires and fresh-frozen Achilles tendon augmentation for both sides. The necessity of a cast (6 weeks) after surgery in order to protect the suture is mentioned by all authors.
In our case we preferred end to end suture of the tendon and we secured the suture with Dall-Miles cables through the patella and tibial tubercle as suggested by Shelbourne (14). Although the author recommends a 60 degree of knee flexion when the cable is tensioned, we tensioned the cable at 30 degree of knee flexion so that the suture would not be stressed. After surgery, the cooperation between surgeon, patient and a physiotherapist is vital because the recuperation period must be managed with care. The exercises should have a progressive and continuous character for the knee to regain full mobility.

Conclusions
When not associated to underlying pathology, bilateral rupture of the patellar ligament becomes a rarity. The occurrence of such ruptures in young adults without corticosteroid treatment is extremely uncommon, and due to the small number of cases, the incriminated factors are still controversial. In this particular case, the rupture mechanism consisted in hyperflexion of the knee; a possible contributing factor was the increased weight of the patient. The chosen surgical technique (end-to-end techniques reinforced with a Dall-Miles cable) has the advantage of a fast rehabilitation; the patient does not need to remain immobilized, thus contributing to an early postoperatively initiation of recovery. Another advantage consists in the fact that the quadriceps is immobilized only for a short period of time, preventing the atrophy of the muscle.

References
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