Patellectomy, an old treatment in patellar fracture which is still alive: A case report

Abstract

Introduction

Comminuted patella fractures comprise 55 % of patellar fractures. In spite of advances in internal fixation of patella, patellectomy remains an effective treatment in comminuted fractures. In the shadow of different efficient methods of internal fixation, little attention is paid to patellectomy as an old treatment in patellar fracture which is a treatment option in circumstances like comminuted fractures and osteomyelitis.

Presentation of case

A 54-year-old male presented with complaint of knee pain and limited range of motion. The patient experienced patella fracture four years ago and several sessions of surgery have been performed on his patella including tension band wiring, partial patellectomy, and arthroscopic release. Lastly, pain and severe limited range of motion, convinced us to perform total patellectomy. The result is satisfactory after one year; flexion is up to 90° and no limping or extension lag is observed. The only complaint is mild anterior knee pain.

Discussion

Patella has two important biomechanical functions including linking and displacement. Preserving even a single fragment of the patella substantially improves linking and displacement function of the patella. Total patellectomy is reserved for conditions like failed internal fixation, comminuted fractures, and patellar osteomyelitis. Although function of the knee cannot be thoroughly restored after removing of the patella, total patellectomy can lead to a relative satisfaction in performing activities of daily living.

Conclusion

In spite of various types of treatment for patellar fracture, total patellectomy, is still an efficient treatment option in circumstances like comminuted fractures, failed internal fixation, and osteomyelitis.

Highlights

• •The patella reduced torque necessary to extend the knee by displacing the quadriceps away from the knee center of rotation.
• •Preserving even a single fragment of the patella substantially improves linking and displacement function of the patella.
• •Total patellectomy is reserved for rare conditions like failed internal fixation, comminuted fractures, and osteomyelitis.
• •Total patellectomy can lead to a relative satisfaction in performing activities of daily living.

1. Introduction

Patella was considered a vestigial embryologic remnant for many years and it was believed that impairs quadriceps function and strength of the knee [1,2]. Consequently patellectomy was accepted as a reasonable treatment in patellar fracture [1]. By the years Clinical studies indicated degenerative changes, decrease quadriceps strength, and functional disability following total patellectomy [3]. In spite of advances in internal fixation of patella, patellectomy remains an effective treatment in comminuted fractures [4] which comprise 55 % of patellar fractures [5].

In the shadow of different efficient methods of internal fixation including tension band wiring, cannulated screw, and basket plate fixation little attention is paid to patellectomy as an old treatment in patellar fracture which is still a treatment option in circumstances like comminuted fractures and osteomyelitis. The present case which is reported in line with the SCARE criteria [6] is trying to indicate performing total patellectomy with accurate surgical technique and appropriate post-operative rehabilitation program can result in satisfactory functional outcome and can be the first treatment option in patients with comminuted patella fracture.

2. Case presentation

A 54-year-old male presented with history of patella fracture four years ago which had been underwent several sessions of surgery (Fig. 1A, B).

Fig. 1.

A, B; Comminuted patellar fracture of the patient. C, D; First operation- TBW and k-wire fixation.

Firstly, open reduction and internal fixation (ORIF) of the fracture was performed with k-wire and tension band wiring (TBW) (Fig. 1C, D). Due to limited range of motion of the knee and patellar non-union, arthroscopic release of the knee, quadricepsplasty, and re-ORIF of the patella with TBW was performed a year after fixation of the patella.

Two years later, the patient presented with limited range of motion (ROM) and non-union of patella fracture. In addition to arthroscopic release and partial patellectomy, the remaining parts of patella were fixed with polyester (ethibond) suture and patellar tendon augmented with hamstring allograft.

Lastly, after four years from the onset of the trauma, the patient referred to our center (a tertiary referral hospital) with the complaint of knee pain and limited range of motion. He has experienced pain in left knee for the past six month, especially at the end of range of motion. The pain was progressive and aggravated by physical activity. Although it was initially reduced with rest and analgesics, recently became permanent. Patient also suffered from progressive limited ROM which was severely advanced at the time of visit (0-0-10 degrees). Patient's pain and limited ROM resulted in limping and interfering with his daily activities. The patient reported no past medical history. No specific drug history was recorded, except analgesics.

In appearance, there was no evidence of warmness or erythema over the knee. He had tenderness over the knee cap. The knee couldn't be flexed more than 10°. Consequently, he had an abnormal gait. The patient was able to perform straight leg raise (SLR) and extensor mechanism could produce full extension of the knee. Varus and valgus stress tests and neurovascular examination were normal.

According to mentioned clinical status of the patient and failed internal fixation of the patella, total patellectomy was planned for the patient. Longitudinal skin incision was done over the patella. All bony fragments were removed and Integrity of retinaculum and extensor mechanism preserved during the procedure. Lengthened extensor mechanism after excision of the patella, was corrected through tendinous repair by purse-string suturing technique and advancement of vastus medialis oblique (VMO). The repair tightened at 90° of flexion. After excision of the patella, the knee was manipulated under anesthesia. Range of motion of 0-0-100 was achieved in operating room (Fig. 2, Fig. 3).

Fig. 2.

Surgical technique of fourth operation- total patellectomy. A; Longitudinal incision on patella. B, C; Preserving patellar tendon attachment to the tibial tubercle.

Fig. 3.

Post-operative x-ray after total patellectomy.

Passive range of motion was started post-operative and patient discharged with 0–90 degree passive knee ROM. Physiotherapy was initiated after two weeks and progressive physical therapy was continued under supervision of physical therapy specialist.

Now, after one year of the last surgery, patient is able to flex the knee up to 90° and there is no extension lag (Fig. 4). No limping is observed. Mild anterior knee pain is the only complaint of patient which is occurred during long distance walking.

Fig. 4.

Clinical evaluation after one year of follow up. A; Full extension without extension lag. B; Straight leg raise.

The case has been reported according to the SCARE criteria [6]. The patient was informed that data concerning the disease would be submitted for publication and he agreed for publication.

3. Discussion

Many of our daily activities like ascending stairs, walking, standing from a chair rely on an intact extensor mechanism. Extensor mechanism is responsible for active knee extension and maintains the knee in an extent position [7].

The patella has two important biomechanical functions during knee extension including linking and displacement. Patella acts as a link between the quadriceps and the patellar tendon during initial phase of knee extension [8]. Extension of the knee from 45° of flexion to terminal extension rely on displacement function of the patella [9] The patella increases the moment arm by displacing the tendon away from the center of rotation of the knee [7] and therefor reducing torque necessary to extent the knee, specially the last 15° of terminal extension [10] (Fig. 5). Force requires for knee extension is less when excision of one-half of patella or less is done compare to total patellectomy. Distal to proximal excisions is more beneficial biomechanically specially when at least three-fourths of the length of the proximal patella can be preserved [11]. Extensor mechanism generates high amount of torque which is as large as three to seven times of body weight. The torque results in significant patella-femoral contact forces. The smaller the patella-femoral contact zone the greater contact stress generates and so increases the risk of articular damage and osteoarthritis [12]. So, preserving the patella is crucial to maintain extensor mechanism optimal function, however in some condition like the case we reported there is no way to preserve the patella, and it is important to lower the burden of total patellectomy by accurate surgical technique and appropriate post-operative rehabilitation program.

Fig. 5.

Displacement effect of patella results in reducing torque necessary for knee extension. E is the torque produced by the extensor mechanism, which is divided into E1 and E2. E1, which is the amount of torque that directly extend the knee, increases with increasing the angle between the leg and the extension of the thigh. The higher this angle, the greater the amount of E torque is assigned to E1.

Extensive comminution of the distal pole or a fragment of the patella which cannot be fixed internally is indication for partial patellectomy [4,13]. In addition, small fragments that are detached from surrounding soft tissue and devascularized fragments should be removed. Total patellectomy is indicated for comminuted fractures in which there are no large fragments to be stabilized by internal fixation [14]. Preserving even a single fragment can substantially improve linking and displacement function of the extensor mechanism. So total patellectomy is reserved for rare conditions like failed internal fixation or patellar osteomyelitis [11].

Equivalent functional outcomes to open reduction and internal fixation have been reported for partial patellectomy [7,15,16]. Partial patellectomy may even result in superior results in patients with extensive inferior pole comminution [17]. Total patellectomy results in inferior outcomes compare to internal fixation or partial patellectomy [18]. So it is recommended only in fractures with severe comminution [19,20]. Total excision of patella was associated with high prevalence of chronic pain, reduction in strength of the extensor mechanism, quadriceps atrophy, loss of range of motion, and instability of the knee joint [3,14]. For these reasons, total patellectomy is not a favorable procedure and retaining even a single fragment significantly improves the function of the extensor mechanism [7].

4. Conclusion

Patella as a part of extensor mechanism plays two important roles for integrity of biomechanics of the knee joint including; linking and displacement. Although preserving the patella is crucial for normal knee function, there are circumstances which require sacrificing the patella such as comminuted fractures and osteomyelitis. So total patellectomy, an old treatment of patellar fracture is still alive and although function of the knee cannot be thoroughly restored after removing of the patella, it can lead to a relative satisfaction in performing activities of daily living.

Declaration of competing interest

The authors declare no conflict of interest in this study.