Patellar Tendon Rupture

Updated: Mar 30, 2021
Author: Christopher C Annunziata, MD; Chief Editor: Thomas M DeBerardino, MD, FAAOS, FAOA 


Practice Essentials

The patellar tendon serves as the distal extent of the quadriceps insertion. Rupture of the patellar tendon usually occurs at the osseotendinous junction and causes complete derangement of the knee extensor mechanism. This is a disabling injury in an active person, resulting in an inability to actively obtain and maintain full knee extension.

The patellar tendon ruptures relatively infrequently. However, the complications of an untreated rupture to the extensor mechanism can be extremely disabling. If the tendon does not heal properly and at the correct length and tension, knee range of motion (ROM) and strength can be altered significantly, leading to early fatigue, patellofemoral pain, and, possibly, instability, which can thereby prevent return to preinjury status.[1, 2]

Immediate surgical repair is recommended for optimal return of knee function and power. Surgical intervention allows excellent recovery of motion and strength, provided that the injury is diagnosed in a timely fashion and repaired immediately.

In the past, the surgical technique for acute rupture of the patellar tendon was primary suture repair. Augmentation of the repair was believed to be necessary and was achieved by using a cerclage of wire, suture, or autogenous graft (eg, semitendinosus) in order to reinforce the repair.[3]  Routinely, the knee was kept locked in extension for up to 6 weeks to prevent undue stress on the repair.

Earlier and more aggressive rehabilitation techniques are now available. Krackow introduced a novel interlocking stitch technique,[4]  and Marder and Timmerman demonstrated that repair alone is equally durable without augmentation.[5]

The focus of this article is acute patellar tendon ruptures, especially those associated with acute sports-related injuries. Patellar tendon ruptures also can occur as a complication of total knee arthroplasty,[6]  anterior cruciate ligament (ACL) reconstruction using the patellar tendon as an autograft,[7]  or excision of chronic tendinosis. However, the etiology and treatment in these circumstances are beyond the scope of this article.


The patellar tendon is actually a ligament connecting two bones, the tibia and the patella. The extensor mechanism of the knee starts proximally as the quadriceps femoris muscle group. Anteriorly, the fibers of the rectus femoris tendon traverse the patella and condense inferior to the patella to insert on the tibial tubercle as the patellar tendon.

The fibers of the vastus lateralis expand to the superolateral border of the patella and proximal tibia to form the lateral retinaculum. Similarly, the tendons of the vastus medialis insert into the superomedial border of the patella and tibia to form the medial retinaculum. The retinacula converge into the patellar tendon. Injuries to the tendon usually involve the adjacent retinacula as well, causing dysfunction of the entire extensor hood.


Unilateral traumatic ruptures of the patellar tendon tend to occur when a violent contraction of the quadriceps is resisted by the flexed knee (eg, during landing after a jump). The estimated force required to disrupt the extensor mechanism has been reported to be as high as 17.5 times body weight.

In the flexed knee position, the patellar tendon sustains greater stress than the quadriceps tendon, and the tensile load is much higher at the insertion sites than in the midsubstance of the tendon. Therefore, the patellar tendon most commonly ruptures near its proximal end, off the inferior pole of the patella.

Given that considerable force is needed to rupture a healthy tendon, it is likely that ruptures occur in areas of preexisting disease.


Patellar tendon rupture often occurs in the setting of long-standing patellar tendon irritation. The rupture is the final result of chronic tendon degeneration due to repetitive microtrauma. Histopathologically, ruptured tendons studied by Kannus et al demonstrated changes consistent with chronic inflammation and degeneration.[8]

Ruptures also may occur after local injection of corticosteroid near the inferior pole of the patella as treatment for patellar tendinitis (ie, jumper's knee). This complication, first reported in 1969 by Ismail et al[9] and later elucidated by Kennedy et al,[10] is probably a result of steroid-induced breakdown of collagen organization and strength. In a series by Kelly et al, nearly 60% of patients who sustained patellar tendon ruptures had received an average of two or three steroid injections around the patellar tendon before rupture.[11, 6]

Patellar tendon rupture is usually unilateral and is the result of a traumatic athletic injury. The typical mechanism is a sudden eccentric contraction of the quadriceps, usually with the foot planted and the knee flexed as the person falls. However, in the setting of systemic inflammatory disease, diabetes mellitus, or chronic renal failure, bilateral ruptures can occur with lower-energy stress.[12, 13, 14, 15] Additionally, patellar tendon ruptures can result from a posterior knee dislocation.[16]

Systemic disorders are related to an increased incidence of tendon ruptures. Pritchard et al found that tendon ruptures in systemic lupus erythematosus (SLE) appear to be associated with extended disease duration, long-term corticosteroid therapy, evidence of steroid-induced musculoskeletal complications, minimal disease activity at the time of rupture, and deforming hand arthropathy.[17]

Inflammatory changes have been noted at the site of rupture in patients with SLE,[18] amyloid deposition has been noted at the site in patients with chronic renal failure undergoing dialysis,[19] and elastosis has been noted in patients with chronic acidosis.[20]

Anatomically, the patellar tendon tends to tear in the midsubstance in patients with systemic disease, rather than at the osseotendinous junction, as typically occurs in acute traumatic injury. After a tear of the midsubstance, tendon repair and rehabilitation can be especially difficult, and the difficulty is exacerbated by the preexisting comorbid condition.

Patellar tendon ruptures also can occur after surgery for total knee arthroplasty, procedures using the central third of the patellar tendon as an autograft, or excision of patellar tendinosis.


The true incidence of patellar tendon rupture is not known, but this injury is observed less frequently than rupture of the quadriceps tendon and usually occurs in those younger than 40 years. It has been quite rare in children, but its frequency has been growing in this population as a consequence of increased participation in sports and high-energy recreational activities during childhood.[21] Overall, patellar tendon rupture is the third most common injury to the extensor mechanism of the knee, following patellar fracture and quadriceps tendon rupture.[22, 23]


Immediate surgical repair of the ruptured patella tendon is recommended for optimal return of function. Outcome after repair is closely related to the length of time between injury and repair. If the tendon is repaired immediately, most patients experience nearly full return of knee motion, quadriceps strength, and preinjury activity levels.[24, 25, 26, 27]  Persistent quadriceps atrophy is common but is not considered a complication, in that the atrophy does not prevent the return of strength.

Reasonable function can be obtained in most individuals, especially in those with an acute tendon rupture that is repaired immediately. Multiple authors have attributed an earlier return to preinjury activity to a more aggressive rehabilitation program with an emphasis on earlier ROM.[28, 29, 30, 31]

Because of the relative infrequency of patellar tendon rupture, the sample sizes in all the studies are rather small, and a meta-analysis has yet to be performed to further delineate the statistical significance of an aggressive rehabilitative protocol. Nonetheless, there appears to be a definite trend toward aggressive postoperative rehabilitation for earlier return to preinjury activity, much like that observed with the repaired Achilles tendon.




In most instances, the history, the physical examination, and standard radiographs suffice for making a diagnosis of acute patellar tendon rupture.

Disruption of the patellar tendon is associated with immediate disabling pain. Acute rupture frequently results in an immediate "pop" or tearing sensation. The patient usually notes immediate swelling and difficulty with rising and weightbearing after the injury.

Physical Examination

On physical examination, diffuse swelling in the anterior knee with ecchymosis, hemarthrosis, and patella alta is observed. Tenderness exists along the anterior knee and retinacula, and a defect at the level of the rupture is usually palpable (see the image below), though significant swelling can make this difficult to appreciate initially. The patella may also feel proximally displaced as compared with the contralateral side.

Patellar tendon rupture. This image depicts the de Patellar tendon rupture. This image depicts the defect within the patellar tendon at the inferior pole of the patella.

The patient is usually unable to bear weight, especially in a single-leg stance, and has a tense hemarthrosis. With a tendon rupture extending through the medial and lateral retinacula, active extension is completely lost, and the patient is unable to maintain the passively extended knee against gravity. If the rupture involves only the tendon and the retinacular fibers remain intact, some extension is possible, though an extensor lag is noted.

Occasionally, a deceleration injury can cause a disruption of the extensor mechanism. In this setting, it is also important to assess both the integrity of the meniscal cartilage with palpation of the joint line and the anterior cruciate ligament (ACL) with a Lachman test.[32]

If the diagnosis of tendon rupture is delayed, scar tissue may obliterate what previously had been a palpable defect. In this scenario, some degree of active extension may be possible, but with weakness and some degree of extensor lag. Quadriceps atrophy may also be noted, with considerable weakness, especially with weightbearing, stair climbing, and rising from a seated position. The weakness can exist to such a degree that the patient performs a forward thrusting motion of the limb in the swing phase of gait and complains of stance instability.



Laboratory Studies

In the circumstance of patellar tendon rupture secondary to systemic disease, such as chronic renal failure, systemic lupus erythematosus (SLE), rheumatoid arthritis, or diabetes, the tendon rupture is rarely the harbinger or the first symptom of the disease. Therefore, although abnormal laboratory values may be found in the face of and consistent with the systemic disease, laboratory studies otherwise are rarely indicated in the workup for patellar tendon rupture.

Plain Radiography

Plain radiographs (anteroposterior [AP], lateral, and axial) should be obtained in all patients presenting with a traumatic injury to the knee or with a hemarthrosis. Contralateral films should also be obtained as a means for comparison of patellar height. Even if a palpable gap in the extensor mechanism allows easy recognition of a patellar tendon rupture, radiographs are still necessary to assess for any other concomitant abnormalities.

The lateral view is particularly helpful to determine whether a patellar rupture has occurred. The classic finding is patella alta, but one may also notice calcification indicative of chronic patellar tendinosis (see the image below). In addition, the axial view assists in determining whether any preexisting patellofemoral arthritis exists, which may impact the rehabilitative efforts and prognosis.

Patellar tendon rupture. A lateral radiograph of t Patellar tendon rupture. A lateral radiograph of the right knee from a patient with an acute patellar tendon rupture. Note the superior patellar migration as well as the calcification below the inferior pole of the patella. This represents preexisting calcification within the patellar tendon, which likely contributed to the rupture.

The so-called empty Merchant sign on the Merchant view has been suggestive as a sensitive and specific indicator of acute patellar tendon rupture, one that physicians can learn to recognize with very little training.[33]


High-resolution ultrasonography (US) can be useful in the diagnosis of acute and chronic patellar tendon ruptures. Hypoechogenicity is associated with acute tears, whereas thickening of the tendon at the rupture site and disruption of the normal echo pattern are observed with chronic tears.

Although US is widely available and does not expose the patient to radiation, many do not have the experience necessary to perform or interpret this type of study reliably. For this reason, US is not routinely employed for the diagnosis of patellar tendon rupture in the United States, though it is used quite frequently for this purpose in Europe.

Ultrasound elastography (USE), in the form of either compression elastography (CE) or shear-wave elastography (SWE), has been advocated on the grounds that in comparison with conventional US, it may yield increased sensitivity and diagnostic accuracy in tendinopathy and may be able to detect pathologic changes before they are visible on conventional US.[34] However, the procedure has several technical limitations, and standardization remains to be achieved.

Magnetic Resonance Imaging

If the diagnosis cannot be established on the basis of clinical and radiographic examination, magnetic resonance imaging (MRI) is the imaging study of choice. The typical finding is discontinuity of tendon fibers with adjacent hemorrhage or edema.[35]


No diagnostic procedure is routinely necessary to identify an acute patellar tendon rupture. If a question or concern exists of an intra-articular fracture or osteochondral injury, the joint can be aspirated to look for fat droplets. The routine use of aspiration and injection is not recommended.


Blazina, Kerlan, and Jobe described three clinical stages of patellar tendinitis (ie, jumper's knee) that culminate with patellar tendon rupture.[36]

Initially, the insidious onset of aching in the knee centers over the infrapatellar region and localizes to the inferior pole of the patella. This usually arises after the patient engages in repetitive activity such as jumping, climbing, kicking, or running.

During the first stage of the tendinitis, the pain is present only after athletic participation. The pain typically disappears after a period of rest. Sensations of weakness or "giving way" are transient and are never associated with locking or catching.

In the second stage, pain and symptoms occur at the beginning of an activity, disappear after a warmup, and then reappear after completion of the activity. The aching becomes more persistent, and eventually the discomfort persists throughout the entirety of the activity, but athletic performance is not significantly impaired.

In the third stage, the symptoms are the same but more prolonged, and performance is definitely impaired. The athlete might even become apprehensive about further participation.

Finally, if the athlete continues with intensive activity despite exacerbation of symptoms, he or she eventually may experience a sudden catastrophic "giving way," with pain and inability to actively extend the knee. This coincides with an acute and complete rupture of the patellar tendon.



Approach Considerations

Early diagnosis and definitive treatment provide the best results. The type of treatment depends predominantly on the extent of the tear. The most common injury involves acute complete disruption of the tendon with subsequent dysfunction of the extensor mechanism. In this setting, surgical repair is the treatment of choice. In general, repair should be performed as soon as possible after the injury to limit the degree of quadriceps atrophy and prevent any contractures that might make the procedure more difficult.

In some situations, a partial tear of the patellar tendon may occur. The patient may be able to maintain full active extension and normal patellar height. This individual can potentially be treated nonoperatively with immobilization until the tendon has healed. However, one must be certain that the tear is, in fact, partial before initiating this program. Magnetic resonance imaging (MRI) may be useful in this situation (see Workup).

The chronicity of the tear is another factor that must be considered. After approximately 6 weeks, direct repair becomes challenging, if possible at all, with native tissue; other techniques may be necessary to establish continuity of the extensor mechanism.

In a prospective study that included 17 patients (average age, 30 years; range, 22-36 years), Abdou investigated the use of hamstring tendon autograft in the treatment of chronic rupture of the patellar tendon.[37]  Patients underwent regular follow-up (average, 21 months; range, 12-30 months) after clinical and radiographic preoperative and postoperative evaluation. The author concluded that hamstring tendon autograft is safe and effective for patellar tendon reconstruction and that it affords good ligament reconstruction.

Regardless of the timing, repair or reconstruction is still the optimal treatment in a patient who has sustained a patellar tendon tear with subsequent patella alta and extensor mechanism dysfunction.

With disruption of the extensor mechanism of the knee, no absolute contraindications have been cited for the acute traumatic patellar tendon rupture. Perhaps in the case of an open, grossly contaminated wound, the need for a staged reconstruction following surgical debridements can be entertained. Nonetheless, the need for reestablishment of the extensor mechanism cannot be underestimated.

Medical Therapy

Nonoperative treatment has a limited role in the care of patellar tendon ruptures. For the rare patient who has a partial patellar tendon tear with maintenance of patellar height, cast or brace immobilization in full extension for 6 weeks, followed by a therapy program to regain motion and strength, may be appropriate. Progress must be slow to allow for tendon-to-bone healing. Strengthening exercises should be delayed for at least 3 months.

Surgical Planning

Choice of technical approach

Complete tears of the patellar tendon are best addressed by means of early surgical intervention. This affords the best opportunity for anatomic repair of all the injured structures within the extensor mechanism.

Several techniques have been described for the immediate repair of the acutely ruptured patellar tendon. In general, repair involves suturing the torn tendon through bone tunnels within the patella or tibial tubercle, depending on the location of the disruption. Additionally, retinacular tears are repaired anatomically.

In the unusual case of chronic patellar tendon tears, direct repair may be challenging or impossible. Surgical correction may be performed in stages, depending on the degree of patella alta and peripatellar scarring. Typically, the repair needs augmentation. Alternatively, the patellar tendon can be replaced with allograft or autograft tissue.[38, 39, 40, 37]

Substantial progress has been made in surgical technique and clinical care for acute patellar tendon ruptures, including the use of the anterior cruciate ligament (ACL) tibial guide, augmentation with Dall-Miles cables[29]  or nonabsorbable suture, and aggressive rehabilitation for improved range of motion (ROM) and strength. In the future, suture anchors may alleviate the need for creating tunnels through the patella and could decrease surgical morbidity by allowing the use of a smaller incision and facilitating more consistent anatomic placement of the torn site onto the patella.[41, 42, 43]

Preparation for surgery

As with any procedure, both the tissues and the patient must be ready for surgical intervention. The ultimate outcome depends not only on the anatomic repair of the extensor mechanism but also on the rehabilitative efforts of the patient. It is important to stress in the preoperative period the importance of participating in the postoperative rehabilitative protocol so that maximal range of motion and strength can be achieved.

Patellar tendon ruptures with concomitant retinacular tears (see the image below) commonly result in diffuse swelling and ecchymosis along the anterior knee. Therefore, delaying surgical intervention until the inflammation begins to diminish may be safer. This 4- to 7-day delay may decrease the risk of wound complications.

Patellar tendon rupture. This intraoperative pictu Patellar tendon rupture. This intraoperative picture depicts a rupture of the patellar tendon from the inferior pole of the patella with associated medial and lateral retinacular tears.

Additional issues that should be considered are the extent of pathology within the ruptured tendon, the degree of patella alta, and the possibility of concomitant injuries within the knee. Extensive tendinosis or calcification within the ruptured tendon may compromise the repair. Although no studies have focused specifically on this issue, the surgeon may choose to excise this pathologic tissue and may subsequently need to supplement the repair with additional tissue. Therefore, the patient and the surgeon must be ready to accept this alternative.

Because anatomic repair is the goal, the surgeon must identify the appropriate patellar height for the injured patient. A radiograph of the contralateral knee can serve as a template intraoperatively to assist in recreating the normal patellar position.

Concomitant injuries to the menisci, articular cartilage, or supporting ligamentous structures may be present. Depending on the location and extent of injury to these structures, additional intervention may be necessary. Therefore, the surgeon must consider this possibility in the preoperative period so that surgical incisions are well planned and the material needed for repair or reconstruction is available.[44]

Repair and Reconstruction of Ruptured Patellar Tendon

The patient is positioned supine on the operating table after a regional or general anesthetic is administered. Because nonabsorbable material is used, a first-generation cephalosporin typically is administered. The procedure begins with an examination of both knees. ROM assessment and ligamentous examination are performed to determine whether any motion deficits or concomitant ligamentous injuries are present.

A tourniquet is placed on the involved leg, and typically, both legs are cleansed and draped free. After the limb is exsanguinated and the tourniquet started, a straight midline longitudinal incision is made that extends from the superior pole of the patella to the medial aspect of the tibial tubercle. Thick medial and lateral subcutaneous flaps are created to the extent of the retinacular tears.

The torn end of the patellar tendon is then mobilized and minimally debrided of friable tissue. Depending on the location of the tear, the tibial tubercle, inferior pole of the patella, or both are debrided of soft tissue and subsequently decorticated with a curette or bur (see the image below).

Patellar tendon rupture. The inferior pole of the Patellar tendon rupture. The inferior pole of the patella is debrided of soft tissue, then decorticated.

Troughs are not created. Two No. 5 nonabsorbable sutures are then inserted with a Krackow stitch into each half of the tendon (see the image below).[45]  Three parallel tunnels are placed through the patella or tibial tubercle.

Patellar tendon rupture. Two Krackow stitches with Patellar tendon rupture. Two Krackow stitches with number 5 nonabsorbable sutures are sewn through the patellar tendon.

The authors advocate the technique described by Ong and Sherman, in which an ACL tibial tunnel guide is used during this aspect of the procedure to maneuver the drill more accurately to the desired endpoint (see the image below).[46]  Using the tunnel guide decreases the risk of violating the articular surface, reduces the number of passes required to obtain an optimal position, minimizes injury to the quadriceps tendon, and eliminates the additional step of retrieving sutures through drill holes.

Patellar tendon rupture. An anterior cruciate liga Patellar tendon rupture. An anterior cruciate ligament tibial tunnel guide is positioned along the anterior half of inferior pole and angled such that the drill exits along the superior pole of the patella. A total of 3 parallel tunnels are created. Note the contralateral knee within the operative field, which later serves as the guide in recreating normal patellar height.

The drill is then replaced with a Beath pin (see the first image below). The inner limbs of each stitch are passed through the central tunnel, and then the outer limbs are passed through the outer tunnels (see the second image below). In certain situations, the authors have used suture anchors in both the patella and the tibial tubercle with good results, but at this time, they still favor the use of tunnels.

Patellar tendon rupture. The Beath pin replaces th Patellar tendon rupture. The Beath pin replaces the drill bit. The suture is then placed through the eyelet.
Patellar tendon rupture. All of the suture ends ar Patellar tendon rupture. All of the suture ends are now along the superior pole of the patella. The inner limbs of the stitches are within the central tunnel while the outer limbs are within the corresponding outer tunnels.

A drill hole is then created transversely through the tibial tubercle, and an additional No. 5 nonabsorbable suture is passed through this hole. This suture is then passed superiorly within the quadriceps tendon along the superior pole of the patella (see the image below). This is accomplished by passing a 16-gauge spinal needle along the superior pole and then threading the suture through.

Patellar tendon rupture. A cerclage stitch was pas Patellar tendon rupture. A cerclage stitch was passed along the superior pole of the patella and through a tunnel within the tibial tubercle. This is now being tensioned to maintain normal patellar height so that the repair sutures can now be tied.

Both knees are then positioned in 30° of flexion. The patellar height is measured from the tibial tubercle to the inferior pole of the patella on the noninvolved leg and recreated in the involved leg by increasing tension in the cerclage suture.

Once the correct position is obtained, the repair sutures are tied and the knee reexamined to assess the degree of knee flexion that can be obtained without causing excessive tension on the repair. Alternatively, an intraoperative radiograph can be obtained on the involved knee, before the repair sutures are tied, and compared with the radiograph of the contralateral knee obtained in the preoperative period.

The repair site is then oversewn with 0 absorbable suture to bring the loose ends remaining on the avulsed side over the repair. The retinacular tears are closed with the same suture material but with the knee held in 30º of flexion to limit the possibility of capturing the knee and thus limiting motion (see the image below).

Patellar tendon rupture. The repair is now complet Patellar tendon rupture. The repair is now complete with recreation of normal patellar height. The retinacular tears were repaired with absorbable suture with the knee positioned in 30° of flexion.

The wound is then closed in standard fashion, with an effort made to minimize the amount of grasping of the skin edges. Ideally, this should further diminish the risk of wound breakdown in this inflamed tissue. A standard dressing is applied, followed by a self-contained cooling device and hinged knee brace locked in extension.

Situations exist in which acute repair with sutures alone is not adequate. This may be the case when the patient has a midsubstance tear, has a chronic rupture, or has undergone a previous resection of chronic patellar tendinitis or a recent ACL reconstruction with the use of patellar tendon autograft.

In these situations, augmentation or reconstruction may be necessary. Described techniques involve the use of both autograft (eg, hamstrings,{ref3657-INVALID REFERENCE} fascia lata, or central quadriceps tendon) and allograft (eg, Achilles tendon) tissue, as well as synthetic material.[38, 39, 40, 47, 48, 49, 50, 28, 51, 52, 53]  Regardless of the material used, these techniques generally involve weaving the supplemental tissue through the native patellar tendon or through bone tunnels within the patella, tibial tubercle, or both.

In the individual with a chronic tear, other factors are involved. Because the patella has been retracted for an extended period, significant scarring may develop, which limits the surgeon's ability to recreate normal patellar height and the ability to regain full knee motion. Adequate mobility can usually be obtained after thorough debridement of the medial and lateral gutters and subperiosteal elevation of the vastus intermedius from the anterior femur.

If this is inadequate, a two-stage reconstruction with preoperative traction with the use of a transverse Steinmann pin placed in the patella can be performed. When the remaining tendon is scarred and attenuated, a Z-lengthening of the quadriceps and Z-shortening of the patellar tendon can be performed. This allows sliding of the patella back to the anatomic position. A reconstructive technique as mentioned above then should follow.[47, 48, 49, 54]

Allograft reconstructive techniques have also been described for care of the chronic patellar tendon rupture.[50, 55]  The procedure involves placement of the bone-block end of the graft into a trough created in the tibial tubercle. The tendinous end is then split and passed through one or more tunnels within the patella and/or encircling the patella medially and laterally.

Postoperative Care

The ultimate goal of the surgical repair is the return of normal knee mechanics and strength. To achieve this goal, it is important for the repair to be stable enough to allow early, controlled ROM as described by Marder and Timmerman.[5] Provided that a stable repair has been achieved, a standard postoperative protocol may then be followed (see Table 1 below).

Table 1. Standard Postoperative Protocol (Open Table in a new window)

Time After Surgery




0-3 d

None, with use of crutches

Hinged knee brace locked in extension

1. Motion - None

2. Modalities and/or exercises - None

4-13 d

Toe touch with crutches

Hinged knee brace locked in extension

1. Motion - Active flexion to 45° and passive extension to 0° (no active extension) 3 times a day

2. Modalities and/or exercises - Swelling control with ice, gentle medial and lateral patellar mobilization, gentle isometric hamstring exercises, contralateral isometric quadriceps exercises 3 times a day

2-4 wk

Partial (25-50%) with crutches

Hinged knee brace locked in extension

1. Motion - Active flexion to progress to 90° and passive extension to 0° (no active extension) 3 times a day

2. Modalities and/or exercises - Swelling control with ice, gentle medial and lateral patellar mobilization, gentle (~25%) isometric quadriceps exercises (sets, no straight leg raises), continue with ipsilateral hamstring exercises and contralateral quadriceps exercises 3 times a day

4-6 wk

Progress to weightbearing as tolerated, crutches discontinued when good quadriceps control is obtained

Hinged knee brace locked in extension

1. Motion - Active flexion to progress as tolerated and passive extension to 0° (no active extension) 3 times a day

2. Modalities and/or exercises - Swelling control with ice, gentle medial and lateral patellar mobilization, gentle (~25%) isometric quadriceps exercises (sets, no straight leg raises), continue with ipsilateral hamstring exercises and contralateral quadriceps exercises 3 times a day

6-12 wk

Weightbearing as tolerated

Hinged knee brace locked in extension until good active quadriceps control and normal gait are obtained

1. Motion - Progress to full 3 times a day

2. Modalities and/or exercises - Swelling control with ice, more aggressive medial and lateral patellar mobilization, begin straight leg raises without resistance, continue with ipsilateral hamstring exercises and contralateral quadriceps exercises 3 times a day; start stationary cycling at 8 weeks

12-16 wk

Complete weightbearing

No immobilization

Progress with quadriceps strengthening (isokinetic) exercises and start neuromuscular retraining

16-24 wk

Complete weightbearing

No immobilization

May start running and sport-specific training

>6 mo

Complete weightbearing

No immobilization

May return to jumping and contact sports when obtain 85-90% of strength of contralateral extremity on isokinetic strength testing

For tenuous repairs, whether for acute or chronic tears, a more conservative program is used and tailored to the situation. Generally, strict immobilization is recommended for 6 weeks, followed by ROM exercises. Strengthening exercises are then started approximately 3 months after the repair, followed shortly thereafter by neuromuscular retraining. Return of quadriceps bulk and strength usually is delayed, and return to premorbid athletic activities may take approximately 9-12 months.


Not infrequently, decreased quadriceps strength and loss of full knee flexion can complicate the overall success of a repair. Prolonged immobilization leads to stiffness. Manipulation under anesthesia or arthroscopic lysis of adhesions may be necessary to improve motion.

Occasionally, the decreased ROM can be attributed to patella infera (sometimes referred to as patella baja). In this condition, the patella lies more distal than normal, which can result when the tendon is relatively shortened by the repair. Patella infera can be a very challenging problem if severe and locked down. If only mild stiffness is noted, manual superior, inferior, medical, and lateral guides performed passively can be helpful. If ROM is severely restricted, the patient should follow up with the surgeon.

Rerupture, failure of fixation, or both also can occur, especially in patients who return to athletic endeavors before the tendon is completely healed. The repeat injury may require a revision of the repair.[56, 57] Inadequate placement of the suture repair or failure to recreate the appropriate patellar height can cause patellofemoral pain.

Wound breakdown and infections can occur, as with any other surgical intervention. These complications may be slightly more common in this region because of limited soft tissue along the anterior knee and operating through inflamed tissue. To diminish these potential wound complications, perioperative antibiotics and closed-suction drains can be used, the initial incision can be made through uncompromised skin, and grasping of the skin edges can be kept to a minimum.

Long-Term Monitoring

After an adequate repair allowing for an aggressive postoperative rehabilitative program, the follow-up care goals, with intervals dated as time after surgery, are as follows:

  • 3-5 days - Adequate pain control, decrease in swelling and wound check
  • 2 weeks - Active flexion to 45º, full passive extension
  • 4 weeks - Active flexion to 90º, maintenance of full passive extension
  • 6-8 weeks - Full active flexion
  • 3 months - Straight leg raise with no extension lag
  • 6 months - Symmetric quadriceps size and strength