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N Am J Sports Phys Ther. 2006 August; 1(3): 124–131.
PMCID: PMC2953362

Use of Knee Extension Device During Rehabilitation of a Patient with Type 3 Arthrofibrosis after ACL Reconstruction



Arthrofibrosis is a frequent complication following rehabilitation of a patient with anterior cruciate ligament (ACL) reconstruction. Although prevention is the best treatment, little information exists within the literature regarding the management and rehabilitation intervention for arthrofibrosis. In this case report a rehabilitation program in the treatment of a patient with arthrofibrosis is described.


To identify the importance of discrete measures of knee range of motion in the knee of a patient following ACL reconstruction in order to help prevent postoperative complications.

Case Description

The patient was an 18-year-old female who sustained an ACL and medial collateral ligament (MCL) injury in a basketball game and underwent an ACL reconstruction with an ipsilateral patellar tendon graft. The patient developed arthrofibrosis and, despite traditional physical therapy of therapeutic exercise and manual therapy, the patient continued to complain of pain, stiffness, limited activities of daily living, and the inability to participate in competitive sports. This patient used a knee extension device as part of her rehabilitation program.


The patient was able to obtain knee extension and flexion equal to her opposite normal knee. Upon completion of the rehabilitation program, the patient returned to full activities of daily living and competitive sports.


Increasing and maintaining knee extension that is equal to the opposite normal knee is an important component in the successful outcome for the patient after ACL reconstruction. The use of a knee extension device may provide an effective rehabilitation intervention in the treatment of arthrofibrosis.

Keywords: arthrofibrosis, anterior cruciate ligament, rehabilitation


Arthrofibrosis is an abnormal proliferation of fibrous tissue in and around a joint that can lead to loss of motion, pain, stiffness, muscle weakness, swelling, and limited activities of daily living. This condition can occur after an injury, or more commonly, after surgery.112 Arthrofibrosis remains a common postoperative complication after anterior cruciate ligament (ACL) reconstruction despite the choices of graft selection. Patellar tendon grafts, hamstring grafts, and allografts are the most commonly used grafts selected for ACL reconstruction, and arthrofibrosis has been found to occur after all three. While a greater incidence of arthrofibrosis occurs with a patellar tendon graft, this condition continues to be prevalent in patients who received hamstring grafts and allografts, as well.13,14

Shelbourne et al10 classified different types of arthrofibrosis in the knee based on the loss of knee extension, flexion, or both; the location of scar tissue formation intra-articularly; and the mobility and location of the patella (Table 1). Prevention of arthrofibrosis is the preferred treatment and is possible with a structured rehabilitation program.12 However, once arthrofibrosis has occurred, the treatment approach widely varies. Numerous published surgical reports exist regarding the cause and treatment of arthrofibrosis, but the rehabilitation programs are poorly defined.1,3,57,9 For the physical therapist, even fewer guidelines exist with no consistent consensus among researchers as to the most effective treatment and postoperative rehabilitation.

Table 1.
Classification of Arthrofibrosis.

The importance of obtaining and maintaining knee extension following ACL reconstruction is well documented in the literature.1,4,1012,15 Most treatment approaches for arthrofibrosis include surgical intervention followed by extension casting and “aggressive” physical therapy. Published reports discuss the use of serial casting, “drop out” casts and daily physical therapy.8,10 This approach is often a time consuming event requiring daily cast changes and multiple visits to the clinic or hospital. However, the best treatment approach in achieving range of motion (ROM) after surgical intervention requires further investigation. Many times, patients with arthrofibrosis will undergo multiple surgeries and extended lengths of time in physical therapy, which can become very costly and time consuming.

The purpose of this case report is to describe the use of a knee extension device in the treatment of a patient with Type 3 arthrofibrosis. In this case a unique knee extension device was used as part of a home exercise program.


The patient was an 18-year-old female who tore her right ACL and medial collateral ligament during a basketball game on 10-28-03. She was evaluated by an orthopedic surgeon and placed in a knee brace that was locked at 30°. The patient was instructed by the physician to perform quadriceps muscle contractions and straight leg raise exercises. She underwent medial collateral ligament repair and ACL reconstruction using an ipsilateral patellar tendon graft on 12-09-03. After surgery, the patient's knee was kept in extension by a knee brace and she was limited to toe touch weight bearing for four weeks.

The patient began formal physical therapy for ROM and patellar mobilization on 12-31-03 and was advised by her physician to continue to wear the knee brace locked at 0° to 90°. Due to the slow progress in ROM, the patient underwent a right knee manipulation and arthroscopy on 02-06-04. After surgery, the patient continued with physical therapy for ROM exercises and was prescribed methylprednisolone (steroid for inflammation). Over the next month, the patient had her knee aspirated twice, was placed on rofecoxib (non-steroidal anti-inflamatory - NSAID), and repeated a dose of methylprednisolone. The patient continued to complain of pain and stiffness in her right knee. As of 03-19-04, her right knee ROM was still significantly limited at 0-10-108º.

The patient underwent a second right knee manipulation and arthroscopy on 03-22-04 (Table 2). Postoperatively, the patient was placed on prednisone (steroid for inflammation) and issued a continuous passive motion (CPM) machine to assist with ROM. Upon follow up, the patient was diagnosed with arthrofibrosis. She was instructed to continue with physical therapy and placed on cyclobenzaprine, a muscle relaxer. She additionally received bupivacaine (analgesic for pain) injections prior to physical therapy appointments to help make her physical therapy more tolerable. She was attempting to run and bike but continued to have significant pain and stiffness. The patient was then referred to the Shelbourne Clinic at Methodist Hospital for a second opinion on examination and treatment of her knee on 05-25-04.

Table 2.
Order of events following previous treatment.

Initial Physical Therapy Examination

Physical examination showed that the patient had an antalgic gait and was walking with a bent right knee. She had right quadriceps atrophy. The patient's knee had a mild effusion, good patella mobility in all directions, a negative Lachman test, negative posterior drawer, and negative varus and valgus laxity with testing. The patient felt no tenderness to palpation over the medial collateral ligament or the patellar tendon. She was able to perform a leg raise with a bent knee and significant extension lag. Plain radiographs were read as normal.

Range of motion measurements were taken using a goniometer as described by Norkin.16 ROM measurements were recorded as A-B-C, with A being the degrees of hyperextension, B indicating lack of extension from zero, and C documenting degrees of flexion.17 Her right knee ROM was 0-10-110° vs. her normal left knee 10-0-150º, which means she was lacking 20º of extension and 40º of flexion.

The International Knee Documentation Committee subjective knee form (IKDC) outcome instrument was used to assess the patient's current condition.18 The initial score on the IKDC was 41/100 and is representative of a significant amount of disability.

The patient was diagnosed with Type 3 arthrofibrosis. The patient had been undergoing regular physical therapy in her home town three times per week since her ACL reconstruction. After discussing the details of the physical therapy sessions, it became apparent that the focus of the rehabilitation program had been on strengthening and not ROM. Therefore, the present focus was to try nonoperative methods to maximize her knee ROM and restore knee symmetry. The goals of physical therapy were to increase right knee ROM equal to her left knee, decrease swelling, restore a normal gait pattern, increase leg strength equal to her left knee, and return to normal activities of daily living and eventually full competitive basketball.

Physical Therapy Intervention

The loss in knee extension is more problematic and causes more limitations than a loss of knee flexion.1,8 Aglietti et al1 showed that patients who have better knee ROM before surgery have a better prognosis and outcome after surgical intervention. Therefore, the initial plan of care focused on treating the knee extension loss. Paulos et al8 showed that it is difficult to obtain and maintain both flexion and extension at the same time and achieving extension should be a priority. The treatment was initiated to focus on increasing knee extension only. Most uninjured, normal knees have some degree of hyperextension. De Carlo and Sell17 found normal knee extension to be 5º of hyperextension in males and 6º of hyperextension in females. Normal knee ROM is defined as ROM equal to that of the noninvolved limb to include the measurement for hyperextension. The patient's normal, uninvolved knee extension measured 10° of hyperextension. Therefore, our goal was to maximize knee extension equal to the opposite normal knee.

A knee extension device (Elite Seat, Kneebourne Therapeutics, Noblesville, IN) was used that would stretch the knee into hyperextension (Figure 1). The second author (KDS) is a part owner of Kneebourne Therapeutics which designed and developed the knee extension device. This device is patient controlled and provides a low load, long duration stretch.19 The patient was issued and instructed to use the extension device for 10 minutes 3-4 times per day followed by additional knee extension exercises. These exercises included a towel stretch and heel prop exercises and active terminal knee extension while standing. The towel stretch is an exercise that focuses on increasing extension and forcing the knee into knee hyperextension (Figure 2) . The patient was advised in performing a heel prop and it was to be performed whenever the patient was sitting (Figure 3). She was also instructed to stand on the involved extremity and attempt to extend the knee into a locked out position by an active quadriceps contraction (Figure 4). This exercise assisted in maintaining the extension acquired from the previous exercises. All exercises were performed three times per day. The patient received instruction in gait training and was encouraged to walk full weight bearing with a normal, symmetrical gait pattern. Finally, she was issued and instructed in a cold/ compression device (Cryo/Cuff, Aircast Inc., Summit, New Jersey, USA) to help control swelling and soreness.

Figure 1:
Elite Seat: The Elite Seat is a knee extension device used to increase knee extension.
Figure 2:
Towel Stretch: The towel stretch exercise is performed to increase knee extension. A towel is placed around the ball of the foot and the opposite hand holds down the distal part of the thigh. The patient pulls the towel up bringing the knee into hyperextension. ...
Figure 3:
Heel Prop: The heel prop is performed by placing a bolster under the patient's heel allowing the knee to fall into hyperextension.
Figure 4:
Standing knee lock-out: The patient shifts his/her weight to the involved extremity and forces the knee into hyperextension by a quadriceps contraction.

Given that the patient lived approximately 5 hours of driving time from the clinic, she was set up on a home exercise program as described previously to focus on increasing and maximizing her involved extremity knee extension. Her progress was monitored through phone calls. Two weeks later she returned for a follow-up evaluation and presented with increased ROM. Her right involved knee measurement was 5-0-110° vs. 10-0-150º in the left normal knee. On physical examination, she was able to perform a straight leg raise and an active heel lift (Figure 5); however, this activity was not equal to the opposite knee. The patient's knee had a mild effusion and she walked with a slightly bent knee. The patient reported that her knee was still very sore. The patient was advised to continue with her current home exercise program focusing on increasing her knee extension until she felt she was no longer making improvements.

Figure 5:
Active Heel Lift: The patient is able to lift his/her heel off the table and make the knee go into hyperextension by contracting the quadriceps muscle.

The patient returned 2 weeks later (1 month after her initial visit) to check her progress following this new treatment. She felt she had maximized her knee extension at that time and was feeling most of her discomfort in the anterior aspect of the knee while using the knee extension device and performing the exercises. Upon physical examination, she continued to walk with a bent knee and had a mild effusion. Her ROM measured the same as her previous visit, still lacking both extension and flexion. She continued to have pain with walking, stairs and activities of daily living. The patient's desire was to return to high-level sports and she planned on playing basketball at a college later that year. Given that her knee was still lacking ROM and she was having pain and difficulty with activities of daily living, the patient elected to undergo an arthroscopic scar resection as recommended by the physician.

Surgical Intervention

The patient underwent an arthroscopic scar resection on 07-19-04, approximately 6 weeks after her initial presentation to the present clinic (Table 3). Informed consent was obtained and the rights of the subject were protected for a study in the follow up of patients undergoing knee arthroscopy. She underwent the surgical procedure as described by Shelbourne et al10 for Type 3 arthrofibrosis.

Table 3.
Order of events using knee extension device.

The patient was kept overnight in the hospital and received intravenous Toradol for inflammation and pain control. An anti-embolism stocking was applied to the patient's leg and the leg was elevated in a CPM machine to help prevent postoperative swelling. She was also placed in a CryoCuff (Aircast Inc., Summit, New Jersey, USA) to assist in preventing a hemarthrosis.

Post Surgical Physical Therapy Intervention and Examination

On the day of surgery, exercises for extension were immediately initiated. The knee extension device was used for 10 minutes, followed by 10 towel stretch exercises, and quadriceps activation to achieve and maintain an active heel lift. She followed this exercise with 10 straight leg raises to maintain good leg control and avoid quadriceps inhibition. These exercises for knee extension were performed six times per day. The patient was on bed rest for the first three days postoperatively to minimize swelling. Bed rest is an important concept after surgery since evidence exists that a hemarthrosis may contribute to an inhibitory effect on the quadriceps and hamstrings muscles resulting in muscle atrophy.20 Early quadriceps muscle activation plays a key role in achieving and maintaining knee extension.8 Therefore, although the patient was on bed rest to minimize swelling, she was performing a regular exercise program to achieve and maintain full terminal hyperextension equal to the opposite knee. Full weight bearing with a normal gait pattern was emphasized and allowed for restroom privileges only.

The patient was discharged from the hospital to a nearby hotel. Prior to discharge, her ROM was 10-0-90º in the right involved knee versus 10-0-150º in the left knee. She had a moderate effusion and walked full weight bearing with a slightly antalgic gait pattern. The patient was discharged from the hospital with a home exercise program. She was to remain supine in the CPM with continuous use of the cold/ compression device. Six times throughout the day, she took her leg out of the CPM machine, removed the cold/compression device and performed the exercise program, which included the extension device for 10 minutes, towel stretch exercises followed by active quadriceps muscle activation 10 times, and straight leg raise exercises 10 times. The patient then reapplied the cold/compression device and placed her leg back in the CPM machine. Full weight bearing and a normal gait pattern was encouraged and emphasized for restroom privileges only.

At three days postoperatively, she returned to the clinic to have her ROM and progress evaluated. She continued to achieve full passive terminal hyperextension equal to the opposite knee, an active heel lift, a straight leg raise, and her knee had a moderate effusion. Knee flexion exercises were instituted because she had excellent leg control and equal knee extension. She was instructed in heel slide and wall slide exercises and was told to discontinue flexion exercises if she noted any loss in knee extension. She was instructed to continue to use the extension device and perform all exercises 3 to 5 times per day. She was told to perform a heel prop exercise when sitting and to stand on the involved extremity forcing the knee locked out by an active quadriceps muscle contraction when standing.

At 10 days postoperatively she had maintained her full passive terminal hyperextension equal to the opposite normal knee, an active heel lift, and was walking with a normal gait. Her knee had a mild effusion and ROM measured as 10-0-125º in the right involved knee versus 10-0-150º in the left normal knee. She was instructed to continue to focus on perfect knee extension and to increase her knee flexion until she could sit on her heels equally and comfortably (Figure 6). No strengthening exercises were initiated so that the focus continued to be on achieving full knee ROM.

Figure 6:
Sitting on Heels: Equal knee flexion can be demonstrated by having the patient sit on his/her heels comfortably and symmetrically.

She returned 08-31-04, approximately six weeks postoperatively, and she rated her knee at 60% and had returned to all normal activities of daily living including helping out on the family farm. She continued to perform the prescribed exercises four times per day. Her ROM on the right involved knee was 10-0-143° versus 10-0-150º in the left normal knee. She was able to sit on her heels but had an uncomfortable tilt. Her knee had a mild effusion and she had a normal gait, no tenderness, and an active heel lift that was not yet equal to the opposite normal knee. She was instructed to continue with her previous home exercise program but she could gradually decrease using the extension device to 1-2 times per day as long as she did not lose extension. Upon achieving full ROM symmetrically equal to the opposite knee, she was able to begin biking and elliptical cross trainer, single-leg press, single-leg extensions, and step down exercises. These exercises were performed one time per day, 3 - 5 times per week. Progression of the low-impact and strengthening program was allowed as long as no ROM was lost or compromised.

On 09-23-04, approximately two months after her surgery, she underwent isokinetic strength testing at 180° and 60º speeds and single-leg hop testing.21 These strength tests were repeated at four, six, and eight months postoperatively. At four months she was allowed to begin shooting baskets and light agility drills. At eight months postoperatively she was released to full participation (Table 3).


At four months postoperatively, the patient had symmetrical knee ROM including full equal hyperextension and full equal flexion. She had an equal active heel lift and was able to sit on her heels equally and comfortably. Isokinetic strength testing of the involved knee compared with the opposite normal knee revealed 79% strength at 180°/s speed and 66% strength at 60°/s speed. She rated her knee at 80%.

At one year postoperatively, the patient's knee had symmetrical ROM including full equal hyperextension and full equal flexion. She had an equal active heel lift and was able to sit on her heels equally and comfortably. Her quadriceps muscle strength was 89% of the opposite normal knee at 180°/s speed and 96% strength at 60°/s speed with isokinetic strength testing. She tested 101% on the single-leg-hop test. She rated her knee at 98% and her knee had a mild effusion. The patient's IKDC score at one year postoperatively was 97/100, more than doubling the score she achieved on her initial visit. Additionally the patient returned to full athletic competition without pain or difficulty and was formally discharged from physical therapy at that time.


The treatment of arthrofibrosis is often a costly and time intensive treatment process. The focus of treatment in most published articles is in regards to surgical intervention with varying rehabilitation protocols. Authors of previously published papers state the importance of acquiring extension but no consensus exists on the best way to achieve this movement.24,8,11,22 Some authors have tried extension casts which require multiple visits to the clinic and can be very uncomfortable. In addition, a cast prevents the patient from being able to perform exercises in between visits. The use of the extension device used with the patient in this report allowed for a patient controlled intervention in increasing knee extension to include hyperextension.

Although most authors agree that restoration of normal knee ROM is a key tenant of treatment, disagreement exists as to what constitutes “normal” ROM. Other treatment programs to regain knee extension fail to take into account that most people have some degree of knee hyperextension. Many authors report they had achieved good ROM results by achieving zero degrees, however, these authors still did not have a good outcome.1,57,9,22 Achieving full hyperextension equal to the opposite normal knee was the focus of this rehabilitation utilizing the knee extension device. Previous attempts in physical therapy that utilized therapeutic exercises and manual therapy had failed. In this case report, full ROM equal to the opposite normal knee was achieved and it is the author's opinion that this achievement of full extension was the most important factor in returning the patient to an active lifestyle, including competitive basketball.

Maximizing extension preoperatively may have helped in obtaining full extension postoperatively. Avoiding a hemarthrosis and subsequent quadriceps inhibition after surgery allowed for early quadriceps activation and the ability to maintain full terminal knee extension. Once the patient was able to maintain extension, flexion exercises were initiated followed by the rehabilitation program described earlier.


While prevention provides the best treatment for arthrofibrosis, a need exists for data on the best way to treat arthrofibrosis once it has occurred. This case is an example of a successful outcome in the treatment of Type 3 arthrofibrosis in which a knee extension device was utilized. The rehabilitation program described in this case study may assist physical therapists and physicians in the treatment of patients with arthrofibrosis.


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Articles from North American Journal of Sports Physical Therapy : NAJSPT are provided here courtesy of The Sports Physical Therapy Section of the American Physical Therapy Association