Ossified proximal patellar tendon rupture
- Vishwas Hosur Ravishankar ,
- Khaldoun El Abed and
- Riaz Ahmad
- Orthopaedics, Weston General Hospital, Weston-super-Mare, UK
- Correspondence to Mr Vishwas Hosur Ravishankar; vishwas.ravishankar@nhs.net
Abstract
Extensor mechanism injuries are not uncommon in young active individuals. Patellar tendon is a part of extensor mechanism of the knee which is commonly ruptured due to forced eccentric contraction against flexed knee. There have been reports of pathological changes in the patellar tendon which eventually lead to the rupture. The common pathologies include hypoxic tendinopathy, mucoid degeneration, calcific tendinopathy and tendolipomatosis. We report a rare case of ossified proximal patellar tendon rupture in a fit and active skittle player, who sustained indirect injury to knee while playing soccer. The rupture was confirmed on examination and radiographs. We discovered intraoperatively that the ruptured proximal patellar tendon was ossified which was sequentially repaired with two Krackow sutures, JuggerKnot suture anchor and finally augmented with Leeds Keio tape. Postoperatively, a knee brace was used to immobilise in knee extension with progressive increase in range of motion. This report supports the pool of evidence suggestive of patellar tendon pathology in causing ruptures.
Background
Patellar tendon rupture and disruption of knee’s extensor mechanism is not unusual, and affects the patella bone more frequently.1 They usually occur in active patients secondary to overload of the extensor mechanism complex which comprises quadriceps, quadriceps tendon, patella, patellar tendon and tibial tubercle.2 3 Some of the risk factors for patellar tendon ruptures include systemic diseases like rheumatoid arthritis, chronic renal insufficiency, steroid use, fluoroquinolone use and patellar tendinopathy4; that can weaken collagen structures.
We report a rare and an unusual case of proximal patellar tendon rupture which was found to be ossified at the inferior pole of the patella and our surgical way of management.
Case presentation
A 52-year-old man presented to the emergency department with a history of left knee pain, which was noticed while playing soccer. The patient noticed pain after kicking the ball. There was no history of direct trauma to the knee. Afterwards, he was not able to bear weight on his affected leg. It is worthwhile here to note that the he regularly played skittles, which involved kneeling on his left knee and rolling the ball. He had antecedent anterior knee pain prior to rupture, which has been ongoing for 13 years. He was evaluated for anterior knee pain prior to this presentation with an MRI (figure 1), which was done 13 years ago. He was found to have a bony spur at the inferior pole of patella and was advised activity modification, mainly avoiding playing skittles. The pain used to settle with activity modification and analgesics. He was also a marathon runner with no systemic illnesses or comorbidities.
MRI of the knee. Red arrow shows bony spur at the inferior pole of patella.
On examination, he was found to have swelling around his left knee. The inferior pole of the patella was markedly tender to touch. There was a distinct palpable gap felt in the inferior pole of patella. The straight leg raise against gravity was absent. Our initial clinical impression of patellar tendon rupture was confirmed by radiograph of the knee (figure 2). The surgical options included excision of the inferior pole of patella with patellar tendon repair or fixation with repair. We went ahead with the latter in view of the intraoperative findings which are discussed below.
AP radiograph of the knee and lateral radiograph of the knee.
Intraoperatively there was a rupture through heavily ossified patellar tendon along with medial and lateral retinacular tear. It was noted that the ossification was extending to the prepatellar region.
We performed four major steps to manage the avulsion and patellar tendon rupture:
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Krackow sutures: after exposing the patellar tendon, the retracted ends were freshened and were opposed with two Krackow sutures. Three tunnels were made equidistant dividing patella into four quadrants. The two medial ends of the Krackow sutures were passed through the middle tunnel and other two threads through corresponding tunnels. Two knots were tied at the proximal end of the tunnel to seat the ossified patellar tendon.
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Securing the fixation through JuggerKnot 2.9 mm anchor: the ossified patellar tendon was still lifting even after placing Krackow sutures. Hence, we had to consider using a suture anchor. 2.9 mm JuggerKnot suture anchor was placed into the anterior patella and the sutures passed through two holes made in the ossified part.
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Augmentation with Leeds Keio polyester patellar tape was carried out (figure 3) in a figure of eight manner. The tape was passed distally under the tibial tubercle tunnel and proximally under the quadriceps tendon. The tape was tightened at 30° knee flexion. The knot was buried under tibialis anterior.
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Retinacular repair on both the sides was done using interrupted absorbable sutures.
Intraoperative photograph of the augmentation with Leeds Keio polyester patellar tape.
The fixation was confirmed to be satisfactory with intraoperative fluoroscopy (figure 4).
Fluoroscopic image after surgery.
Outcome and follow-up
The patient was immobilised in range of motion (ROM) brace locked in extension for initial 2 weeks. Thereafter, the ROM was gradually increased from 0° to 30°, 0° to 60° and finally 0° to 90° at 2-week intervals. Unrestricted knee ROM was allowed 6 weeks after surgery. Toe touch weight bearing was allowed for initial 4 weeks and full weight bearing from there on. At the most recent follow-up, 4 months after surgery, the patient was fully weight bearing without the brace and knee ROM was 0°–110°. There was no extensor lag. The follow-up X-rays confirmed that the fragment has healed back to its preinjury position (figure 5).
Four months follow-up radiographs.
The patient was happy with outcome. He was progressing as expected with no pain and return to his normal daily activities. The patient has started cycling again and walks 5 miles a day.
Discussion
Ossified proximal patellar tendon rupture is a rare injury. Ectopic ossification in patellar tendon is often observed close to the tibial tuberosity in Osgood-Schlatter’s disease, small areas distal to the inferior pole of patella in Jumpers knee and in more extensive form in patella alta of an injured knee.5 Intraoperatively it was found that the fracture ran through the ossified patellar tendon similar to the description in the case report by Yoon et al.5 The weakest area is the junction between the ossified part and patella bone which ruptures on eccentric loading.5
Yoon et al describe a simultaneous bifocal patellar tendon rupture through both inferior patellar pole and tibial tuberosity.5 The ossification was found to be both at the proximal and distal patellar tendon. Another case report by Cakici et al describe the occurrence of patellar tendon ossification following partial patellectomy.6 In this report, the authors describe extensive ossification of patellar tendon following partial patellectomy, which eventually lead to rupture from the tibial tuberosity. These studies corroborate with our study in identifying the unusual patellar tendon ossification.
In our case, the patient had history of patellar tendinitis with anterior knee pain prior to injury. Boublik et al report that 40% of the patients who had patellar tendon rupture had antecedent anterior knee pain.2 We presume that repetitive micro-trauma as a result of kneeling in the game of skittles caused ossification at the inferior pole of patella and weakened the tendon.
There is a debate on whether excision or osteosynthesis of inferior pole fractures gives better results. Although both are accepted methods of treatment, osteosynthesis has been found to show better postoperative functional results with preservation of patellar height and patellofemoral biomechanics.7 Patella baja which occurs after excision, is unacceptable in some patients especially in those who are active and participate in sports.7 In our case osteosynthesis was performed with pull through sutures, suture anchor and augmentation with polyester mesh.
In conclusion, we present a rare case of ossified proximal patellar tendon rupture associated with antecedent anterior knee pain. We believe repetitive micro-trauma as the cause of this pathology. We describe our surgical plan to restore anatomy and knee extensor function.
Learning points
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This report corroborates the previous studies suggesting patellar tendon ossification resulting in rupture, especially in those with low impact indirect injuries.
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History of antecedent anterior knee pain could be predictive of pathological patellar tendon rupture.
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This report also describes the surgical technique and augmentation of distal patellar pole fracture in preserving extensor mechanism.
Footnotes
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Contributors VHR the first author, was involved in drafting the entire manuscript, from obtaining consent, getting figures to writing the abstract, case presentation and discussion. KEA, the second author, contributed to this article by editing the background and also summarised the learning points. RA was involved in writing discussion and reviewed the article before submission.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Patient consent for publication Obtained.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.
References
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