In patients undergoing dialysis due to chronic renal failure, secondary hyperparathyroidism and renal osteodystrophy may cause degenerative changes and spontaneous rupture of the quadriceps tendon1,2. In the case of spontaneous quadriceps tendon rupture, rerupture after repair is common because of degenerative changes in the tendon and decreased bone mineral density3. For repair of the ruptured quadriceps tendon, transosseous sutures and suture anchors are commonly used4. The suture anchor has the disadvantages of relatively higher cost and higher probability of infection. Especially in patients with poor bone quality, the decreased bone strength and bone density may result in the loosening of suture anchor5. The quadriceps tendon is divided into three layers: the superficial layer (rectus femoris), the middle layer (vastus medialis and vastus lateralis), and the deep layer (vastus intermedius). Considering these layered structural characteristics, we performed a modified transosseous surgical technique that can increase the contact area of the quadriceps tendon for patients with chronic renal failure who are expected to have poor bone quality and tissue healing problems, and successfully re-achieved knee joint function.
Written informed consent was obtained from the patient for the publication of this report including all clinical images.
A 31-year-old male patient presented to our clinic for pain and swelling in the left knee that suddenly occurred while going down the stairs. Although the patient had no family history, he was diagnosed with chronic renal failure at the age of 18 years and started dialysis from the year of diagnosis and underwent hemodialysis three times a week for 13 years until the occurrence of quadriceps tendon rupture. At presentation, he had been taking drugs for hypertension, secondary hyperparathyroidism, hyperphosphatemia, and chronic anemia caused by chronic renal failure. There was no previous injury or discomfort.
At first, the patient complained of tenderness and severe swelling in the patellar area along with limitation of active extension (Fig. 1). Approximately 23 mL of bloody joint fluid was obtained in joint aspiration. Laboratory findings indicated hyperparathyroidism and chronic nephropathy (Table 1). The average T-score on the bone mineral density test was –2.2 g/cm2, indicating osteopenia. On plain radiograph and computed tomography, a bony fragment due to avulsion fracture was observed in the suprapatellar area. On plain sagittal radiograph, the Insall-Salvati ratio was 0.71, which confirmed patella baja (Fig. 2). On magnetic resonance imaging (MRI), the T2-weighted sagittal image showed a complete rupture of the quadriceps tendon that retracted proximally (Fig. 3).
Table 1 . Laboratory findings
| Variable | Value (normal range) |
|---|---|
| WBC (×103/dL) | 7.4 (4−10) |
| Hemoglobin (g/dL) | 9.7 (12−16) |
| Hematocrit (%) | 29.5 (35−48) |
| CRP (mg/dL) | 0.146 (0.0−0.5) |
| Serum BUN (mg/dL) | 57.8 (7−18) |
| Serum creatine (mg/dL) | 11.69 (0.6−1.3) |
| ALP (IU/L) | 1,073 (40−130) |
| Serum phosphorus (mg/dL) | 6.6 (2.5−4.5) |
| PTH (pg/mL) | 606 (15−65) |
| Serum calcium (mg/dL) | 7.8 (2.5−4.5) |
| Vitamin D (pg/mL) | 6.2 (19.6−54.3) |
WBC: white blood cell, CRP: C-reactive protein, BUN: blood urea nitrogen, ALP: alkaline phosphatase, PTH: parathyroid hormone.
Fig. 1. Preoperative gross clinical photograph that shows swelling of left knee joint without external wound.
Fig. 2. Preoperative lateral plain radiography (A) and computer tomography (B) of the left knee show mild inferior displacement of patella (patella baja Insall-Salvati ratio, 0.71) with avulsion bone fragment (arrows).
Fig. 3. Sagittal view of T2-weighted magnetic resonance imaging shows complete rupture of the quadriceps tendon and massive hemorrhage.
After spinal anesthesia, a pneumatic tourniquet was applied to the proximal thigh in the supine position. A vertical skin incision about 12 cm long was made across the midline of the patella, and the distal quadriceps tendon and the patella were exposed. A large amount of hematoma and injured retinaculum were seen. The completely ruptured quadriceps tendon was retracted proximally from the osseous ligament joint area. Small bone fragments at the injured section of the quadriceps tendon were removed, and debridement was performed (Fig. 4A). For fixation, the ruptured tendon was arbitrarily divided into four layers based on the anatomical characteristics of the quadriceps tendon. The superficial, medial, and lateral layers were sutured by the Krackow technique using size 2 Ethibond sutures (Ethicon, Inc.). The deep layer was sutured by the Mason-Allen technique also using size 2 Ethibond sutures (Fig. 4B). At the superior patellar pole, three tunnels were made using a 1.6-mm Kirschner wire at intervals of 7 to 8 mm, which passed vertically and parallel to the patella. Strands of non-absorbable sutures fixed to the distal part of the quadriceps tendon were passed through transosseous tunnels from the proximal to the distal direction of the patella. The medial and lateral layer sutured strands were passed through the medial and lateral tunnel, while the superficial and deep layer sutured strands were passed through middle tunnel using a guide wire. In full extension, each strand was tied at the distal part of the patella so that the ruptured part of the quadriceps tendon could be in contact with the upper pole of the patella without any gap. The medial and lateral retinacula were closed, and wound closure was performed in layers (Fig. 4C and D).
Fig. 4. Intraoperative findings. (A) The quadriceps tendon and extensor retinaculum were ruptured completely, and a massive hematoma was infiltrated. (B) The ruptured quadriceps tendon was divided arbitrarily into four layers. The medial, superior, and lateral portions were sutured using the Krackow technique and the intermediate portion was sutured using the Mason-Allen technique. (C) A transosseous suture was done via three vertical transosseous tunnels. (D) The extensor retinaculum and capsules were sutured.
On the postoperative radiograph, the Insall-Salvati ratio was 0.85, which was within the normal range. MRI showed that the repaired quadriceps tendon was almost in complete contact with the upper pole of the patella (Fig. 5). In the sagittal view of preoperative MRI, the thickness of the quadriceps tendon at four predetermined locations was 7.46 mm (proximal), 12.35 mm (central), 13.77 mm (distal), and 17.55 mm (patellar base length), respectively. In postoperative MRI, the thickness of the repaired quadriceps tendon at the same predetermined locations was 10.15 mm, 13.74 mm, 16.54 mm, and 17.93 mm, respectively (Fig. 6). A long leg splint was applied in the full extension immediately after surgery. After 3 days, edema was improved, and a hinged brace that limited the range of motion from 0° to 30° was applied. Two weeks after surgery, rehabilitation treatment was started to reduce pain and swelling. Quadriceps exercise (Q-exercise) was performed according to the degree of pain, partial weight bearing using crutches was started, and treatment was performed with the hinged brace locked except during passive joint exercise to prevent joint contracture. Passive joint exercises were expeditiously started. To strengthen the quadriceps muscle and ipsilateral hip flexor, Q-exercise and side-lying stretching movements such as lifting the foot to the buttock were continuously performed throughout the whole rehabilitation period. Two weeks after the surgery, the crutches were gradually removed, and practice started to move from partial weight bearing to full weight bearing. The joint range of motion of the hinged brace was increased from 0° to 60°, and the Q-exercise was continued. From the 4th week after the surgery, full weight bearing was carried out, and the range of motion of the joint was increased from 0° to 90°. Active knee flexion for 120° was possible at the 6th week. At the 7th week after surgery, a hinged brace was worn without angle restriction, and the brace was removed at the 8th week after surgery.
Fig. 5. (A) Inferior displacement of patella was corrected in the postoperative lateral plane. (B) T2-weighted image shows repaired quadriceps tendon and the tendon is attached to the whole surface of patella.
Fig. 6. Quadriceps tendon (QT) measurements from preoperative (A) and postoperative (B) magnetic resonance images. Lines showpredetermined locations for measurements: proximal (QT-P), central (QT-C), distal (QT-D), and patellar base (PB).
At the 3-year follow-up, the patient extended his knee to 0° without deficit and walked normally without pain and it was confirmed that there was no evidence of rerupture of the quadriceps tendon on ultrasonography (Fig. 7).
Fig. 7. Patient’s postoperative status. The patient regained active extension of the left knee without deficit.
In patients with chronic renal failure, degenerative changes of a quadriceps tendon may be accelerated leading to spontaneous rupture in the context of hyperparathyroidism and renal osteodystrophy1. In addition, as kidney function deteriorates, the homeostasis of calcium, phosphorus, vitamin D, and parathyroid hormone is destroyed. The bone turnover rate increases due to elevated serum parathyroid hormone as a result of secondary hyperparathyroidism. This leads to weakening of the quadriceps tendon at the tendon-bone junction, which can lead to tendon rupture even with a small external force2. Shah6 described that spontaneous quadriceps tendon rupture in patients with chronic renal failure is twice as common in men as in women, and the average age of injury is 36 years. Moreover, secondary hyperparathyroidism was confirmed in 63% of all patients. In this case, the patient had been on hemodialysis for a long time at the hospital due to renal failure and had an increase in serum parathyroid hormone levels and a lack of serum vitamin D, resulting in degenerative changes, calcification, fatty degeneration, and fibrotic degeneration of the quadriceps tendon.
The quadriceps tendon is divided into three layers: the superficial layer, in which the rectus femoris is the main component; the middle layer, where the vastus medialis and vastus lateralis meet; and the deep layer, where the vastus intermedius is the main component7. This layered structure of the quadriceps tendon can be identified with low signal intensity divided by a linear fat layer in a sagittal plane MRI image8. There are two commonly used methods for the repair of quadriceps tendon rupture: a transosseous suture using bone penetration and a method using suture anchor. Hochheim et al.4 described that there was no efficient difference in the functional outcomes between the transosseous suture and suture anchor. The suture anchor has the advantages of shorter operation time, smaller incision area, and faster recovery period compared with transosseous suture. However, it has the disadvantages of relatively higher cost and higher probability of infection. In this case, the decreased bone strength and bone density may result in the loosening of suture anchor. To minimize the incidence of postoperative infection and decrease the rerupture rate in our patient with immunodeficiency, we repaired the quadriceps tendon using a modified transosseous suture.
In the literature, the distal portion of the ruptured tendon is sutured by two or three parallel sutures (Krackow technique) passing into the vertical transosseous tunnel9. Our newly designed method increases the contact area of repaired tendon in consideration of the patient’s underlying disease. Using the multi-layered structure of the quadriceps tendon, the tendon rupture was arbitrarily divided into four layers. From the proximal portion of the ruptured tendon, superficial, medial, and lateral layers were sutured by the Krackow technique. The deep layer was sutured by the Mason-Allen technique (Fig. 8). The eight strands of sutures passed into three longitudinal tunnels made in the patella and tightly knotted at the lower part of the patella. It is thought that in such an arrangement, strong bonding and traction forces can act more evenly on each suture. In the case of traditional horizontal sutures, it is difficult to achieve sufficient attachment of the deep part of the quadriceps tendon to the superior pole of patella. Further, this method minimizes the anatomical gap between the distal part of the quadriceps tendon and the upper part of the patella, resulting in increased tendon contact area and lower rates of rerupture. In several studies, the average quadriceps tendon thickness at the patella insertion area was 18±3 mm in adult males10. Patellar base length includes quadriceps tendon insertion thickness and suprapatellar fat pad thickness. In this case, spontaneous tendon rupture due to degenerative change leads to loss of suprapatellar fat pad, which fills the deep layer of the quadriceps tendon insertion area. Moreover, the separated deep layer suture was thought to have provided additional fixation force. There was no significant difference when measuring the thickness of the quadriceps tendon performed before and after surgery. It suggests that the suture method used in this case is effective enough to restore the contact area similar to that before the injury.
Fig. 8. Illustration of the surgical procedure. The ruptured quadriceps tendon was divided arbitrarily into four layers. The medial, superior, and lateral portions were sutured using the Krackow technique, and the intermediate portion was sutured using the Mason-Allen technique. The sutures were then passed through threevertical parallel tunnels. Fibrowires were tied the knot under the patella.
However, it was difficult to accurately distinguish the four parts anatomically due to degenerative changes in the quadriceps tendon caused by the patient’s underlying disease, calcification, fatty degeneration, and fibrotic degeneration. The suturing method used in this case is thought to have higher strength and more contact area compared to the existing method. However, due to the lack of comparative analysis studies for postoperative outcomes, there is insufficient evidence to improve fixation.
Herein, we reported a case of spontaneous quadriceps tendon rupture in a patient with degenerative changes and osteopenia who received long-term dialysis. We believe this method of using the anatomically layered structures of the quadriceps tendon provides increased contact area to the repaired tendon and minimizes the anatomical gap between the quadriceps tendon and the superior pole of the patella. This results in increasing the contact area of the tendon successfully.
In this case, our surgical technique could increase the contact area of the repaired tendon using layered structure of quadriceps tendon in the patient with chronic renal failure which is expected to have poor bone quality and tissue healing.
No potential conflict of interest relevant to this article was reported.
Conceptualization, Data curation, Formal analysis, Investigation, Supervision, Visualization: all authors. Writing–original draft: all authors. Writing–review & editing: all authors.
