Quadriceps Tendon Rupture

Updated: Jun 08, 2021
Author: James Edwin Lyle, MD; Chief Editor: Thomas M DeBerardino, MD 


Practice Essentials

Ruptures of the quadriceps tendon are relatively infrequent and usually occur in patients older than 40 years. A strong association exists with numerous systemic diseases and prior degenerative changes in the knee extensor mechanism. Ruptures most often occur unilaterally. Bilateral ruptures are highly correlated with systemic disease but have been reported in healthy patients who do not have predisposing factors.[1, 2, 3, 4, 5, 6, 7, 8, 9]

Patellar tendon ruptures are less common than quadriceps ruptures and tend to occur in patients younger than 40 years. In rare cases, partial ruptures of the quadriceps tendon are seen in young athletes with end-stage jumper's knee.[10, 11, 12, 13]  Jumper's knee usually involves the patellar tendon, though in 25% of cases, the quadriceps is involved.

Complete quadriceps tendon rupture is a disabling injury, and operative repair is required. Lister, in 1878, was the first to report on surgical repair. In 1887, McBurney reported on the first surgical repair in the United States. The injury was a direct blow to the knee, and the tendon was repaired using catgut and silver wire. After several other reports on surgical repair of extensor mechanism injuries were published in the early 1900s, operative management became standard.

In 1949, Steiner and Palmer reported the first case of bilateral simultaneous ruptures of the quadriceps tendons. Since then, several large series of patients undergoing quadriceps tendon repair have been published.[14, 15, 16, 17, 18, 19]  In the past few decades, many case reports of bilateral quadriceps ruptures have been published.[3, 4, 5, 6, 7, 8]

To obtain the best results, early diagnosis and treatment of quadriceps tendon ruptures are essential (see Presentation, Workup, and Treatment).[20]  Particular care must be taken to educate all physicians on the importance of testing the integrity of the extensor mechanism in the injured knee; it is hoped that improved physician awareness will lead to fewer cases of misdiagnosis of extensor mechanism injuries. If intervention is delayed, repair is more difficult and results may be compromised.


The quadriceps muscle is composed of four muscle groups, as follows:

  • Vastus intermedius
  • Vastus medialis
  • Vastus lateralis
  • Rectus femoris

The quadriceps tendon is formed by the convergence of all four muscles just proximal to the superior patella. The tendon is multilayered. The rectus femoris becomes tendinous 3-5 cm proximal to the patella and is the most superficial layer inserting on to the patella. Some of its fibers continue over the anterior patellar surface and contribute distally to the patellar tendon. The middle layer is composed of the vastus lateralis and the vastus medialis.

The vastus medialis, which is composed of the vastus medialis obliquus and the vastus medialis longus, becomes tendinous only a few millimeters from its insertion into the patella. The vastus lateralis becomes tendinous about 3 cm proximal to its insertion into the patella. The deep layer is composed of the vastus intermedius. The tendon has an average thickness of 8 mm and an average width of 35 mm.

Peterson et al found that the blood supply to the quadriceps tendon arises from the descending branches of the lateral circumflex femoral artery, branches of the descending geniculate artery, and branches of the medial and lateral superior geniculate arteries.[21] The superficial layers are well vascularized. In the deep layer, however, there is an oval, avascular area that is 30 × 15 mm in size; it probably plays a significant role in tendon degeneration.


Quadriceps tendon rupture usually occurs distally 0-2 cm from the superior pole of the patella, through pathologic tissue. Various systemic conditions may cause damage to the tendon vascular supply or may disrupt the tendon structure.

Diabetes can cause arteriosclerotic changes in tendon vessels. Fibrinoid necrosis of tendons is seen with chronic synovitis. Hyperparathyroidism causes dystrophic calcifications and subperiosteal bone resorption at the tendon insertion. Obesity causes fatty degenerative changes in tendons and increases the forces on the tendon. Fatty degeneration, fibrinoid degeneration, and decreased collagen are seen with normal aging.

Kannus and Jozsa examined histopathologic changes in 891 ruptured tendons; about 97% of the pathologic changes were degenerative.[22] The degenerative changes included hypoxic degenerative tendinopathy, mucoid degeneration, tendolipomatosis, and calcifying tendinopathy. In the 82 quadriceps tendons, tendolipomatosis was the most common type of degeneration, seen in almost half of the tendons (see the image below). No signs of inflammatory cells were noted in any of the specimens. In 62% of the ruptured tendons, pathologic changes of the tendon blood supply were seen, including vessel narrowing and thrombosis.

Tendolipomatosis. Reprinted with permission from K Tendolipomatosis. Reprinted with permission from Kannus P, Józsa L. Histopathological changes preceding spontaneous rupture of a tendon. A controlled study of 891 patients. J Bone Joint Surg Am. Dec 1991;73(10):1507-25.

Trobisch et al retrospectively reviewed 45 quadriceps tendon ruptures in 42 patients and performed histologic analysis on a tissue sample from the rupture zone in 22 cases.[23] Only 14 (64%) of the 22 samples showed degenerative changes. The ratio of degenerative tendons to nondegenerative tendons rose with increasing patient age. These findings suggested that quadriceps tendon rupture can occur without pathologic tendon degeneration, especially in younger patients.


Quadriceps tendon rupture usually occurs during a rapid, eccentric contraction of the quadriceps muscle, with the foot planted and the knee partially flexed. This injury commonly occurs during falls. Other mechanisms of injury include direct blows, lacerations, and iatrogenic causes.[24, 25, 26, 27, 28, 29, 30, 31, 32]

McMaster showed that normal tendons in rabbits do not rupture under stress. Instead, linear stress causes disruption at the musculotendinous junction, the muscle belly, or the tendinous insertion into bone. Harkness demonstrated that approximately 30 kg/mm2 of longitudinal stress may be applied to normal quadriceps tendons before they fail. Additionally, many ruptures occur after relatively trivial trauma. Therefore, tendon rupture usually occurs through a pathologic area of the tendon.

Many conditions have been reported to contribute to degeneration of the quadriceps tendon, including the following:

Repetitive motion has been implicated as the cause of jumper's knee.[35, 36]

Rare iatrogenic cases have been reported. Examples include rupture after total knee arthroplasty (TKA), lateral retinacular release, meniscectomy, and anterior cruciate ligament (ACL) reconstruction with central-third patellar tendon graft. In addition, steroid injections are believed to weaken tendons. Quadriceps tendon ruptures have also reportedly occurred with knee and patellar dislocations.


When all types of knee injuries are considered, unilateral quadriceps tendon ruptures are relatively rare; bilateral ruptures are even less common. However, quadriceps tendon ruptures are more common than patellar tendon ruptures are, though they are also more likely to be misdiagnosed.[37]

As mentioned previously, quadriceps tendon rupture usually occurs in patients with predisposing factors who are older than 40 years, but these ruptures may be seen in nearly any age group. Siwek and Rao reviewed 69 cases reported in the literature from 1880 to 1978 and found that 88% of the ruptures were in patients aged 40 years or older.[15] To the authors' knowledge, the youngest patient was a 13-year-old who had been immobilized in a long leg cast before sustaining the injury.

In contrast, partial ruptures occur in young athletes.[10, 11, 12, 13] Raatikainen et al reported an average age of 28 years in a series of patients with partial tears.[38] Partial and complete tears occur predominantly in males.


Studies generally have reported good results after early repair of complete unilateral and bilateral quadriceps tendon ruptures.[39]  The type of repair, the location of the tear, the patient's age and sex, and the mechanism of injury do not appear to affect the results. Good range of motion (ROM) usually can be regained, but some persistent quadriceps weakness is fairly common. Most patients can return to their previous occupation, but many cannot return to their preinjury activity level.

In a large study, Konrath et al found that 83% of patients returned to their previous occupations, 51% were unable to return to their preinjury activity levels, and 53% had persistent quadriceps strength deficits (>20% in comparison with the uninjured leg).[19]  The injured leg had a mean thigh atrophy of 1.5 cm as compared with the uninjured leg.

Several studies have shown markedly worse results with delayed repairs. Rougraff et al reported significantly poorer functional results, lower satisfaction scores, and lower isokinetic data in patients with delayed repair.[18]  Raatikainen et al reported good results from simple debridement and repair of partial quadriceps tendon ruptures.[38]

Because quadriceps tendon ruptures are most frequent between the ages of 50 and 60 years, the outcomes of timely surgical repair in older patients have received comparatively little study. Ellanti et al retrospectively reviewed all such ruptures occurring between 2009 and 2014 at their institution in patients older than 80 years (with penetrating trauma and partial ruptures excluded)[40] ; six of the 32 patients (mean age, 81.38 years) were eligible for study inclusion. At last follow-up (mean, 54 months), the mean Lysholm score was 84.8/100 (good outcome), the mean Rougraff score was 21.3/25 (excellent outcome), and all patients considered themselves close to their premorbid mobility level.

In a retrospective continuous study that included 25 knees with acute quadriceps tendon rupture (22 patients; 17 males, 5 females; mean age, 64 years; age range, 52-87 years), Brossard compared the outcomes of suture-anchor fixation and the gold standard technique (ie, transosseous patellar suture).[41] ​ Variables studied included active ROM, muscle strength, patient satisfaction, Lysholm score, return to work, and radiologic behavior of the anchors. At a mean follow-up of 7 years (range, 3-9 years), the outcomes with anchors were comparable to those with the gold-standard technique.




Patients typically present with acute knee pain, swelling, and functional loss after a stumble, fall, or giving way of the knee. There may be no history of prior knee pain. However, younger patients with jumper's knee usually have a history of chronic activity-related pain above the patella that is exacerbated by jumping or kneeling. Specifically ask patients about any history of systemic disease, steroid use, infection, tumors, or prior surgeries. There may be a history of an audible pop at the time of injury.

Physical Examination

Begin the physical examination by noting any obesity. Patients with recent ruptures have difficulty ambulating. Usually, obvious suprapatellar swelling, ecchymosis, and tenderness are present. Carefully evaluate lacerations. There may be a palpable defect in the suprapatellar area and a low-lying patella, but swelling initially may obscure this finding.

Testing for full, active extension against gravity is the most important aspect of the examination. This may make the defect more apparent. Extension lags of varying degrees are seen, depending on the amount of retinacular damage. In incomplete ruptures, the patient may be able to fully extend the knee from the supine position but not from the flexed position. If only tendinitis is present, no extension lag should be noted with any test position. Examine the contralateral knee to rule out bilateral rupture.

If the patient is not seen in the acute phase, diagnosing the rupture becomes more difficult, and it can be easily missed. Ramsey and Muller reported misdiagnosis in seven of 17 ruptures.[14]  Patients with quadriceps tears, especially elderly patients, have been identified as having had and having been treated for strokes, radiculopathy, and myelopathy. Many patients are thought to have only simple knee sprains during their examination in the emergency department and are not given appropriate immediate follow-up.

Pain and swelling decrease over time, and quadriceps function can improve. Patients may be able to ambulate but will do so with a gait demonstrating knee stiffness and elevation of the hip to accommodate the swing-through phase. In addition, patients may have frequent buckling of the knee and difficulty with stair climbing.

Results of neurologic examination are normal except for decreased quadriceps motor function and an absent patellar reflex. Again, full, active knee extension against gravity is the key component of the physical examination.



Laboratory Studies

A preliminary laboratory workup to rule out rheumatologic, endocrine, and renal disease may be indicated in suspicious, presumably healthy individuals with quadriceps tendon ruptures.

Consider a laboratory workup in all cases of bilateral rupture.

Plain Radiography

Several imaging studies are helpful to confirm the diagnosis of quadriceps tendon rupture.[42]  Plain radiography is usually the first imaging modality ordered.[37]

Several abnormalities may be seen on lateral radiographs. These include obliteration of the quadriceps tendon shadow, a suprapatellar mass, suprapatellar calcific densities, spurring of the anterior superior patella, joint effusion, patella baja, and anterior tilting of the superior patella. These findings may be quite subtle or even absent. Patella baja is diagnosed by using the Insall-Salvati index, which is the ratio of the patellar tendon length to the length of the patella. This ratio should near 1, with no more than 20% variation.

On the axial view, the tooth sign, which represents vertical ridging of the osteophytes at the quadriceps insertion, may be seen on the anterior patella (see the image below). In 1977, this sign was first described by Greenspan et al as an incidental finding caused by tendon degeneration[43] ; in 1980, Kelly et al first reported it in association with a quadriceps tendon rupture.[44]

Toothlike ridging of the anterosuperior patella. R Toothlike ridging of the anterosuperior patella. Reproduced with permission from Greenspan A, Norman A, Tchang FK. "Tooth" sign in patellar degenerative disease. J Bone Joint Surg Am. Jun 1977;59(4):483-5.

Use other imaging modalities next to clarify a questionable diagnosis or to differentiate complete and incomplete ruptures.


In complete ruptures, arthrography reveals extravasation of contrast material from the suprapatellar bursa into the soft tissues anterior to the patella, but it is an invasive procedure.[45, 46]


Ultrasonography (US) has high sensitivity and specificity in depicting complete quadriceps tendon ruptures.[47]  An area of hypoechogenicity is seen across the entire thickness of the tendon. In partial tears, a focal hypoechoic defect is seen. In tendinitis, tendon thickening is visualized. US is quick and noninvasive, but its accuracy is highly operator-dependent.

Ultrasound elastography (USE) evaluates mechanical properties of tissues (including tendons) by characterizing their response to stress. There are two major techniques, compression elastography (CE) and shear-wave elastography (SWE). Both techniques have been used for the assessment of the quadriceps tendon.[48]  USE may have greater sensitivity and diagnostic accuracy in tendinopathy than conventional US and may detect pathologic changes before they are visible on conventional US. It appears promising for obtaining an early diagnosis, tracking outcomes, and monitoring treatment in patients with tendon injury. However, it is not yet well standardized, and technical issues remain.

Magnetic Resonance Imaging

Currently, magnetic resonance imaging (MRI) is probably the imaging study of choice when there is any doubt about the diagnosis. MRI can clearly depict the laminated structure of the quadriceps tendon. Complete ruptures show transection of all of the layers of the tendon. Incomplete ruptures show discontinuities of individual layers, with the remaining layers intact (see the image below).

Magnetic resonance imaging (MRI) scans of complete Magnetic resonance imaging (MRI) scans of complete and incomplete quadriceps tendon ruptures. Reproduced with permission from Zeiss J, Saddemi SR, Ebraheim NA. MR imaging of the quadriceps tendon: normal layered configuration and its importance in cases of tendon rupture. AJR Am J Roentgenol. Nov 1992;159(5):1031-4.

An MRI study by Falkowski et al found that quadriceps femoris tendon tears most often involve the rectus femoris or vastus lateralis/medialis layers, usually in proximity to the patella; bony avulsion of the patella is correlated with a more extensive tear of the superficial and middle layers of the tendon.[49]

Histologic Findings

Histologic study is usually not included in the preoperative workup. For histologic details, see Pathophysiology.



Approach Considerations

Early operative repair is indicated for all acute complete quadriceps tendon ruptures, provided that the patient is a suitable surgical candidate. Surgery is also indicated for most chronic complete quadriceps ruptures.[50] Although repair/reconstruction is technically more difficult and results are inferior to those of early repair, successful results have been reported with surgery performed even as late as 1 year following injury. Partial tears may be treated nonoperatively unless they are refractory to a long course of conservative management.

No contraindications for acute repair of quadriceps tendon ruptures exist, provided that the patient is an adequate surgical candidate. For delayed repair/reconstruction, no contraindications for surgery appear to exist up to 1 year following injury. The authors are unaware of any literature on operative management performed later than 1 year following rupture.

With the growing popularity of suture-anchor fixation in other aspects of orthopedic surgery, more research will probably follow to better define the role of this technique in quadriceps tendon ruptures.[41, 51, 52]

Medical Therapy

Conservative treatment is indicated for partial tears.[53] The knee should be immobolized in full extension for 3-6 weeks. Straight-leg raises are started late in the immobilization phase. If these can be performed without discomfort for 10 days, immobilization can be progressively discontinued. Range-of-motion (ROM) exercises are then initiated, and quadriceps strengthening is continued until the strength of the injured leg is equal to that of the contralateral leg.[54]

Surgical Therapy

Choice of surgical approach

Early surgical repair yields the best results for complete quadriceps tendon ruptures.[55, 56, 57, 58, 59, 60] Many techniques have been described for the repair and augmentation of acute and neglected tears, including the following:

  • Use of kangaroo tendon
  • Free fascial grafts
  • Traction sutures
  • Vastus lateralis flaps [61]
  • Carbon fiber [62]
  • Mersilene sutures
  • Dacron graft
  • Polyester graft
  • Autograft of the central third of the patellar tendon

Suture anchors also have come into use,[41, 51, 52] and a suture bridge technique has been reported to be effective in restoring function in cases of quadriceps tendon rupture.[63] However, the following three main types of repair continue to be the most popular:

  • Direct repair of the tendon to the patella
  • Scuderi technique for acute tears
  • Codivilla tendon-lengthening and repair technique for chronic ruptures

A small (N = 4) pilot study by Severyns et al described a technique method for arthroscopic reattachment of the quadriceps tendon with suture anchors.[64] The authors reported no wound healing complications, infectious complications, or repeat tears. 

Operative details

Direct repair of the tendon can be performed for most acute ruptures and for some neglected ruptures. A midline longitudinal incision is made, exposing the rupture (see the image below).

Exposure of a tendon rupture. Exposure of a tendon rupture.

The tear site is irrigated, and the torn tendon edges are debrided back to healthy tissue. Occasionally, if adequate tendon remains distally, an end-to-end repair can be performed. Several heavy nonabsorbable mattress sutures are placed through the tendon, and absorbable sutures are used to reapproximate the retinaculum. Some authors advocate leaving the lateral retinaculum open for better patellar tracking.

Usually, insufficient tendon remains distally, or the tear is at the osteotendinous junction. In these cases, the tendon is repaired to a bony trough in the patella. Again, the proximal tendon edge is freshened. The superior pole of the patella is debrided of any remaining tendon, and a transverse bony trough is made. To avoid patellar tilt, the trough should not be made near the anterior surface of the patella. Three or four longitudinal holes are drilled about 1 cm apart from the bony trough to the inferior pole of the patella (see the image below).

Drill holes through the patella. Drill holes through the patella.

Running interlocked stitches are placed medially and laterally in the tendon with 5-0 nonabsorbable suture. The Bunnell-type weave and Krackow whip stitches are popular. The free suture ends are passed through the drill holes from proximal to distal with a suture passer (see the image below).

Passing suture through patellar drill holes. Passing suture through patellar drill holes.

The tendon then is pulled by the sutures distally into the trough (see the image below).

Tendon pulled down into the patellar bony trough w Tendon pulled down into the patellar bony trough with sutures.

Secure the sutures with a hemostat, and assess patellar rotation and tracking throughout the ROM of the knee. If the assesment is satisfactory, tie the sutures distally and repair the retinaculum with absorbable sutures (see the image below).

Finished repair. Finished repair.

Additionally, if a significant vastus intermedius stump remains, this may be used to augment the repair posteriorly. After routine subcutaneous and skin closure, apply a cylinder cast with the knee in full extension.

If necessary, the repair may be reinforced with extra tissue by using the Scuderi technique. A triangular flap from the anterior portion of the tendon is fashioned, with the base about 5 cm proximal to the tear. The flap should be roughly 3-4 mm thick, 7.5 cm long on each side, and 5 cm wide at its base. The posterior portion of the tendon is left intact.

The apex of the triangle is folded distally and sutured over the repair site. Bunnell pullout wires are placed medially and laterally, running from the quadriceps tendon to the patellar tendon, exiting the skin distally. Following wound closure, the knee is cast in full extension.

For chronic ruptures, a direct repair with augmentation using the Scuderi technique (if necessary) is attempted. The quadriceps tendon and muscle are freed from adhesions. If the tendon cannot be reapproximated to the patella, the Codivilla tendon-lengthening technique can be used. A triangular flap is fashioned that resembles the flap used in the Scuderi technique, except that the Codivilla flap consists of the full thickness of the tendon. Also, the base of the Codivilla flap is more distal, about 1.5-2.0 cm proximal to the tear.

The tendon and retinaculum then are advanced distally until reapproximation is possible. Suturing is performed as previously described. The flap is folded distally and sutured over the repair. The proximal aspect of the open triangle is repaired with absorbable suture. Pullout wires are recommended to protect the repair.

If a defect remains after Codivilla lengthening, options for additional augmentation include the vastus lateralis strip, fascia lata grafts, the sartorius rotational flap, and artificial graft material. If a long course of conservative management for partial quadriceps tendon ruptures fails, surgery may be necessary. Repair using patellar drill holes, as well as simple excision of the scar tissue and closure, has been advocated.

Repeat rupture

If a repeat rupture occurs after surgical repair or reconstruction of a quadriceps tendon rupture, reconstruction is mandatory. Several techniques are available for this purpose (see above).

Maffulli et al described a surgical approach to patellar and quadriceps tendon reconstruction that makes use of an ipsilateral hamstring autograft.[65] In this technique, once the hamstring tendon has been harvested, its ends are prepared by using a whip stitch, and a transverse tunnel is drilled in the middle of the patella. The graft is then advanced through the patella, and sutures are placed to secure it firmly to the openings of the transverse patellar tunnel.

Polyethylene terephthalate tape augmentation has been suggested as a potential solution in recurrent quadriceps tendon ruptures.[66]

Postoperative Care

Sutures or staples are removed at 2-3 weeks. Pullout wires are removed at 3 weeks. Most authors prefer cylinder casting for 4-6 weeks. Immediate postoperative weightbearing as tolerated with a walker or crutches is allowed by many authors. Isometric quadriceps exercises may be started in the cast. When the cast is removed, ROM exercises are initiated along with continued quadriceps strengthening.[67]

A hinged knee brace may be used, with flexion gradually increased over time. Therapy is continued until strength and motion are comparable to those of the uninjured leg. The goal of therapy is to obtain full extension and flexion.

Several authors have advocated immediate postoperative ROM exercises and delayed weightbearing to potentially increase ultimate ROM. Studies also have shown that mobilized tendons heal faster and attain greater strength than immobilized tendons do. In two studies, artificial graft was used to augment the repair and to allow early motion. Konrath et al reported successful immediate motion without routine augmentation.[19]  However, other studies have shown that ROM is routinely regained after up to 6 weeks of immobilization.

Rougraff et al found that nearly all patients (including patients with delayed repairs) regained motion to within 2º of their uninjured leg.[18]  Additionally, this study provided the only comparison of immobilization and immediate motion in the literature up to that point; however, the immediate motion group was very small. No significant difference existed in the ultimate ROM between the groups. Further research comparing larger groups of patients treated with immobilization and early motion is needed to help resolve this issue.

For repair of chronic ruptures, postoperative treatment is similar, but protection of the repair and rehabilitation can be longer. Postoperative care for partial tear repairs requires minimal immobilization and a shorter period of rehabilitation.


The most common complications are loss of motion and extensor mechanism weakness. Infection, wound compromise, and skin breakdown from casting occasionally occur. Although uncommon, malalignment of the patella (including patella alta, patellar tilt, and patellar subluxation) is possible.

Care must be taken to restore normal alignment during surgery, because malalignment can lead to degenerative changes of the patellofemoral joint. Repeat rupture occurs infrequently. Rougraff et al reported two repeat ruptures in 53 repairs,[18] whereas Konrath et al observed one repeat rupture in 50 repairs.[19]

Long-Term Monitoring

Athletes treated for partial or complete ruptures may return to play when several conditions are met, including the following:

  • The patient should have nearly full, painless ROM
  • Knee strength should be at least 85-90% of the other knee
  • Completion of a sport-specific agility program is highly recommended for athletes involved in vigorous sports, such as football, basketball, soccer, or tennis