Anatomy, Pathology, Diagnosis, Treatment, and Rehabilitation

1. What joints are in the knee?
Tibiofemoral, patellofemoral, and tibiofibular.

2. What anatomic structures cause referred pain to the knee?
Lumbar spine, hip, sacroiliac joint, and the ankle or foot, (back, hips, or rest of lower extremity)

3. How should knee ROM be measured and recorded?
ROM should be measured from the lateral side of the patient’s leg with a goniometer. Full extension, an angle between the femur and tibia of 00, should be recorded as 00. Full flexion is recorded as a positive number, somewhere between 00 and 1350. If the patient’s leg cannot be fully extended, the number of degrees possible short of full extension is recorded as a positive number. For example, the patient who lacks 100 of full extension who is able to flex to 1000 should be recorded as having a ROM + 10-1100. If patient’s knee comes to hypertension, then the amount past 00 should be recorded as a negative number. For example, if the subject hyperextends approximately 50 and flexes to 1000, the ROM is recoded as –5-1000.

4. What is a meniscus?
The meniscus is a half moon shaped piece of cartilage that lies between the weight bearing joint surfaces of the femur and the tibia. It is triangular in cross section and is attached to the lining of the knee joint along its periphery. There are two menisci in a normal knee; the outside one is called the lateral meniscus, the inner one the medial meniscus.

5. What is the purpose of the knee menisci?
Multiple purposes: Lubrication, nutrition, shock absorption, and prevention of cartilage wear.

6. Why do meniscal injuries cause gradual swelling and nonbloody effusions?
The menisci are primarily avascular (without a blood supply), especially the inner two thirds.

7. What is the purpose of the ACL?
To prevent anterior displacement of the tibia over the femur (prevents instability of the knee joint)

8. What is a Baker’s cyst?
A herniation of synovial tissue through a weakening posterior capsular wall causing swelling in the popliteal fossa. It is a response to events happening in the anterior aspect of the knee (front). It is not a "true" cyst and no surgery is required nor does it need to be drained since fluid will just reaccumulate posteriorly. Dealing with the problem in the knee joint will typically take care of these.

9. What is patella baja?
Patella baja (also called patella infera) indicates an abnormally low patella that most often results from soft tissue contracture (scarring) and hypotonia of the quadriceps muscle (abnormal weak function) following surgery or trauma to knee. This typically leads to a stiff and less functional knee

10. What is patella alta?
A high-riding patella in relation to the femur. Patella alta is also seen in patellar tendon rupture. This can lead to pain, weakness, or inability to extend the knee.

11. What is genu recurvatum?
Hyperextension or excessive backward knee joint mobility. This often results from individuals with generally lax ligaments.

12. What is genu varum?
Bowleg or excessive outward (lateral) deviation of the leg.

13. What is genu valgum?
Knock-knee or excessive inward (medial) deviation of the leg.

14. What is osteochondritis dissecans?
Also know as OCD, is fragmentation of the articular cartilage with subchondral bone, most commonly affecting the medial femoral condyle or patella. It can be a result of trauma, but is often of unknown (idiopathic) etiology. It predominantly occurs in adolescent males. The usual presentation is stiffness and aching with an effusion. Sometimes it can be treated non-surgically but may need to be treated operatively to prevent further joint collapse.

15. What is a jumper’s knee?
Jumper’s knee is insertional tendinopathy (inflammation where the muscle joins the bone) of the quadriceps or the patellar tendons. The site of involvement is most commonly the inferior pole of the patella in 20–40-year old patients. In patients over 40, the quadriceps tendon is affected more frequently.

16. How do you treat a jumper’s knee?
Nonoperative measures (RICE: rest, ice, compression, elevation).
Nonsteroidal anti-inflammatory medication, such as aspirin or ibuprofen.
Ice massage after activity (control the swelling and inflammation).
Strengthening the quadriceps (helps to balance the forces across the patella)
Hamstring stretching (take pressure off the anterior structures of the knee).
Neoprene sleeves or braces (similar to the ones used for tennis elbow )
Surgery is reserved for patients who experience pain for 6 to 12 months despite close adherence to treatment patients who have suffered a complete tendon rupture.

17. What is Osgood-Schlatter’s disease?
Apophysitis (abnormality) at the insertion of the patellar tendon into the tibial tubercle. Osgood-Schlatter disease is probably the most frequent cause of knee pain in children and it is always characterized by activity-related pain that occurs a few inches below the knee-cap on the front of the knee. It usually responds to rest and gradual ressumption of activities and does not require surgery.

18. What is a plica?
The extra synovium ("remnants") present in the knee joint. During fetal development, the knee is divided into three separate compartments. As the fetus develops these compartments develop into one large cavity (synovial membrane). The majority of people have remnants of these three cavities referred to as a plica. Most often the plica is on the medial (inside) of the knee at the level of the medial femoral condyle. Most individuals are not adversely affected by the presence of plicas. The plica only becomes a problem when there is an inflammation (thickening) in the synovial sack and it begins to catch on the femur as the knee moves, (plica syndrome).

19. What is arthrofibrosis?
Arthrofibrosis is a relatively common complication after total knee arthroplasty with a reported overall incidence of approximately 10%. It can occur after any knee surgery and sometimes after injuring the knee without surgery. It is defined as painful stiffness with scarring and soft tissue proliferation, which results in a reduction in knee range of movement and patient dissatisfaction. There are several risk factors associated with arthrofibrosis. Pre-operative risk factors include limited range of motion, underlying diagnosis (alcohol abuse, obesity), and history of prior surgery. Intra-operative risk factors include surgical technical issues such as improper flexion-extension gap balancing, oversizing or malpositioning of components, inadequate femoral or tibial resection, excessive joint line elevation, creation of an anterior tibial slope, and inadequate resection of osteophytes. Post-operative factors include poor patient motivation, infection,

20. How is arthrofibrosis typically treated?
The basic therapy regimen is early and intensive physiotherapy combined with sufficient analgesia. The next therapeutic steps for persisting arthrofibrosis include closed manipulation under anesthesia and open lysis of intrarticular adhesions. Arthroscopic interventions for lysis of adhesions should be limited to local fibrosis and therapy resistant cases. The choice of revision total knee arthroplasty may be often associated with recurrence of fibrosis. However, revision total knee arthroplasty is preferred for stiffness from malpositioned or oversized components. The management of arthrofibrosis by individualized rehabilitation program that may involve prolonged oral analgesia, continued physical therapy, emotional support, and sufficient patient education remains the accepted treatment option for arthrofibrosis after total knee arthroplasty

21. Does a positive Lachman’s test always mean anterior cruciate ligament (ACL) injury?
No, laxity may be symmetric in the other knee. It is important to compare both knees in most conditions.

22. What is O’Donoghue’s triad?
This is characterized by injuries to the medial meniscus, medial collateral ligament (MCL), and anterior cruciate ligamwnt (ACL). It is caused by a valgus force to a flexed, rotated knee.

23. Describe the typical signs and symptoms of patellofemoral pain.

  • Anterior knee pain with gradual onset that worsens with repetitive knee flexion
  • Pain with prolonged sitting or upon arising after sitting (positive theater sign)
  • Pain with squatting or with descending stairs

24. Name the most common tests for an ACL injury.
Lachman, anterior drawer sign, and pivot shift test. During the Lachman test, the knee is flexed approximately 20 degrees and the proximal tibia is pulled forward to assess excessive translation (more than 3-4 mm). The anterior drawer test follows the same principle but the knee is flexed at 90 degrees. The pivot shift test is performed with the leg in extension. The examiner supports the leg by the upper tibia and flexes the knee while applying a slight valgus stress to the knee (pushing the knee towards the midline). In a knee with an ACL injury, the femur sags backward on the tibia (or conversely, the tibia moves forward on the femur), creating a subluxation of the lateral tibiofemoral compartment. At approximately 30 degrees of flexion, the subluxed tibia suddenly reduces and externally rotates about the femur. The subluxation and the sudden reduction of the knee joint during flexion are termed the "pivot shift."

25. Name the cause and acute signs of a posterior cruciate ligament (PCL) injury?
The most common mechanism of injury of the PCL is the so-called "dashboard injury" (when the knee is bent, and an object forcefully hits the tibia backwards). Another mechanism of injury is hyperflexion of the knee, with the foot held pointing downwards. The acute signs include swelling in the popliteal space with bruising present during the first 36 to 48 hours, and NO effusion due to the extrarticular nature of the PCL. Pain and instability are also common.

26. Name the acute signs of ACL injury.
First, one usually hears a loud ripping sound ("pop") which is usually followed by a rapidly developing effusion (fluid accumulation of the knee)

27. What are the degrees of MCL strains?
Grade 1 (first degree)—valgus stress results in medial pain but no increased laxity.
Grade 2 (second degree)—valgus stress demonstrates increased laxity, and an endpoint is appreciated.
Grade 3 (third degree)—valgus stress demonstrates increased laxity with no appreciable endpoint. This indicates rupture of the ligament and the surrounding capsular structures.

28. How much laxity is there in MCL and lateral collateral ligament (LCL) injuries?
Grade 1 0–5 mm
Grade 2 6–10 mm
Grade 3 11–15 mm

29. How do patients with iliotibial band syndrome (ITB) present?
The patient with iliotibial band syndrome reports pain at the lateral aspect of the knee joint. The pain is worse after strenuous activity, particularly running downhill and climbing stairs. On physical examination, tenderness is present at the lateral epicondyle of the femur, approximately 3 cm proximal to the joint line. Soft tissue swelling may be present, but there is no joint effusion.

30. Can meniscal injuries be treated without surgery?
Yes. Initially, the RICE (rest, ice, compression, and elevation) acronym is prescribed. In fact, most meniscal tears can be treated without the need of surgical intervention.

31. When is surgical treatment indicated for a meniscal tear?

  • Locking, or inability to fully extend the knee because of mechanical blockage
  • Motion restricted despite a trial of physical therapy
  • Instability, which may predispose to further intra-articular damage
  • Persistent Baker’s cyst resulting from a meniscal tear
  • Pain not improving with physical therapy and symptomatic treatment.

32. What is the rationale for the use of knee injections?
There are two types of injections used to treat symptoms of knee osteoarthritis: joint chondroprotective agents (viscosupplementation) and corticosteroids. Viscosupplementation therapy involves injecting a gel-like substance directly into the knee joint. These injections help to restore the lubrication lost by damaged cartilage and may have anabolic (beneficial) effects on articular cartilage. Usually people who respond to this form of treatment will experience some improvement for six to twelve months but sometimes longer. Cortisone injections are reserved for people with a severely inflamed knee with uncontrolled pain. Cortisone injections can provide rapid relief from a tender, swollen osteoarthritic knee which has failed to respond to other forms of treatment. The benefit of an injection may last anywhere from a few days to more than 6 months. They can be repeated safely every few months.

33. What are the types and indications for the use of a knee brace?
According to the American Academy of Orthopaedic Surgeons, knee braces can be classified as:
(1)prophylactic--braces intended to prevent or reduce the severity of knee injuries in contact sports; These braces are often not recommended due to increased number of due to excessive preloading of the medial collateral ligament, limited speed and athleticism, false sense of security for previously injured knee, and brace-related contact injuries to other players.
(2) functional--braces designed to provide stability for unstable knees;
(3) rehabilitative--braces designed to allow protected and controlled motion during the rehabilitation of injured knees.
(4) patellofemoral braces, which are designed to improve patellar tracking and relieve anterior knee pain.

34. What are the surgical options for osteoarthritis of the knee?
Arthroscopic debridement. This includes irrigation and removal of loose bodies from the knee.
Cartilage transplantation. For small isolated areas, portions of autologous articular cartilage can be grafted into the defect.
Osteotomies of the distal femur or proximal tibia are used for isolated lateral or medial compartment arthritis
Unicompartmental knee arthroplasty can be performed for isolated lateral or medial compartment arthritis
Patellofemoral replacement replaces just the patello-femoral joint (anterior part of the knee)
Total knee arthroplasty is used for severe arthritis. Other options depend on the location and severity of the arthritis and include:

35. What is a total knee arthroplasty?
In a total knee arthroplasty, the surfaces of the distal femur, proximal tibia, and often the patella, are replaced. This is performed with a femoral component and a tibial base plate made of a metal alloy, usually cobalt-chromium or titanium. The tibial component has a polyethylene plastic piece that is fixed to the metal base plate and articulates with the femur.

36. What is minimally invasive total knee replacement surgery?
There are many definitions of minimally invasive knee surgery including a skin incision under 14 cm (ranging between 6 and 14 cm), and minimization of soft-tissue dissection (including quadriceps sparing).

37. What are different surgical approaches to the knee?
The conventional medial parapatellar arthrotomy splits and detaches a portion of the quadriceps tendon from the patella.
The midvastus approach involves detaching the vastus medialis fibers that are attached distal to the patella and then splitting the muscle parallel with these fibers from the superior pole of the patella down to their origin on the femur.
The subvastus approach (unlike the medial parapatellar approach) preserves the extensor mechanism and its vascularity. This approach is performed by dissecting around the inner thigh muscle through a natural plane, instead of directly cutting through muscle and tendon (quadriceps) as in traditional approaches.
A new lateral approach for total knee arthroplasty has been recently described. This approach avoids the disruption of the extensor mechanism by entering the joint through the Ilio-tibial band through a lateral skin incision.

38. Are there proven advantages of performing minimally invasive knee arthroplasties?
At this point there is little evidence-based proof with conflicting reports. Some studies report, cosmetic benefits, shorter rehabilitation periods, and higher patient satisfaction. Other studies do not show this and have reported higher complication rates.

39. What is computer assisted total knee replacement surgery?
A method where the surgeon can use a computer to aid during surgery. Often, there is no need for an intramedullary rod and the need for intraoperative x-ray equipment is eliminated. It has been reported to help yield optimal positioning of the components. There are ongoing efforts aiming for a more surgeon-friendly device.

40. What are the indications for total knee arthroplasty?
The primary indication is to relieve pain caused by arthritis. Secondary goals are to restore functions and correct deformity. Candidates should have degenerative changes on radiographs and failed other methods of nonoperative and occasionally other types of operative care. Nonoperative modalitites may include anti-inflammatory medications, assistive devices, weight loss, behavioral modification, oral and intra-rticular chondroprotective agents, and intra-articular corticosteroid injections. In select cases, surgical options prior to total knee arthroplasty include arthroscopy and osteotomies.

41. What happens to the ligaments in a total knee arthroplasty?
In uncomplicated primary knee replacements, collateral ligaments are preserved. Because these structures can tighten and scar with arthritic deformity, they may need to be "released" to a certain degree. This helps to balance the soft tissues to equalize tension in the collateral ligaments and provide stability throughout the range of motion. Occasionally ligaments may need to be tightened. Prostheses require removal of the anterior cruciate ligament. The posterior cruciate ligament is left intact or removed, depending on the type of prosthesis. Prostheses that require removal of the posterior cruciate ligament are designed to substitute for its function in flexion.

42. Should patients have both knees replaced at once?
Many studies have shown that performing both knees at may lessen the morbidity by having only one anesthesia setting. However, for certain patients this may increase the morbidity and mortality for various reasons including possibly the prolonged surgery. Patients where this is not indicated are over 75 or 80 years of age, who may be at increased risk, and certainly patients with cardiac problems.

43. What about replacing only one part of my joint?
Various new techniques have been developed where an entire knee replacement does not have to be performed. In a unicompartmental knee arthroplasty, the surgeon can selectively replace a compartment such as a lateral femoral condyle and lateral tibial plateau. A patellofemoral arthroplasty is performed for the replacement of the patellofemoral joint.

44. What is a patellofemoral arthroplasty?
A procedure in which the kneecap (patellar part), and the trochlea (what articulates with the distal femur), are replaced. Recently, many companies have developed new designs and there are recent reports of better results which were not optimal historically. Presently, about one percent of the knee replacements performed in the United States are patellofemoral arthroplasties.

45. What is the role of pulsed electrical fields in the treatment of osteoarthritis of the knee?
The limited capacity of articular cartilage to heal has stimulated a number of approaches to try to effectuate cartilage repair. Animal and clinical studies have suggested that pulsed electrical stimulation may have beneficial effects on articular cartilage healing. One company markets a product (Bionicare©, Bionicare Medical Technologies, Sparks, MD) that appears to be a safe and effective method for avoiding total knee arthroplasty in some patients and relieving clinical signs and symptoms of osteoarthritis of the knee.

46. What is an "OATS" or "mosaicplasty"?
Osteochondral autograft transfer system (OATS) is a procedure employed for medium sized (approximately 1 to 1.5 square inches) areas of isolated chondral damage (mosaicplasty is utilized for larger areas of damage. The surgeon cores out a circle of damaged cartilage and replaces it with a piece of normal cartilage from a less important part of the same knee, or the contralateral knee (when performing a knee arthroplasty). The underlying principal is that the transferred cartilage will grow to cover the edges of the core with proper cartilage cells and not the weaker fibrocartilage cells.

47. What are the OATS knee surgery requirements?

  • The knee is stable with intact, fully functional menisci and ligaments.
  • Normal knee alignment.
  • Normal joint space.
  • A patient with a body mass index (BMI) of less than 35.

48. What is the rationale of osteotomies for the treatment of knee arthritis?
An osteotomy is used to transfer the weight-bearing forces from one part of the knee to another. It may be used alone to change the weight-bearing forces or in conjunction with other treatment methods such as arthroscopy to try to preserve the knee.

49. When can the patient resume sports activities after an MCL injury?
When the patient’s strength is near normal (90%) and the valgus instability is reduced to a point no longer requiring a brace. The patient should be able to perform one-legged hopping, jumping rope, and climbing stairs before returning to the playing field.

50. Should I use Cox 2 inhibitors?
A number of Cox-2 inhibitors have been taken off of the market recently (Vioxx© (Rofecoxib), and Bextra© (Valdecoxib)). Presently, at least one agent is still being used, and patients should feel safe about Celecoxib (Celebrex©). One of the major side effects of these medications is gastrointestinal (GI) and they should be used with caution if there is any GI related past medical history. Patients with liver or kidney disease (ie; alcoholics), or a history of serious allergic reactions (ie; Sulfas), should be monitored closely for potential worsening of their conditions with the use of the COX-2 inhibitors.

51. Who is at risk for peroneal nerve palsy after a total knee arthroplasty?
The patient with a valgus knee with a fixed flexion contracture is most at risk The peroneal nerve is at risk when a retractor is placed on the lateral side of the knee during surgery. However, injury from this is not a common occurrence. Neuropraxias more often result from stretching of the nerve with correction of the limb deformity..

52. What measures should be taken in the immediate postoperative patient who is found to have new weakness or absence of the foot and ankle dorsiflexors? (peroneal nerve palsy)
All dressings should be removed, and the knee should be flexed to relieve tension across the peroneal nerve. If there is no resolution of the palsy, surgical exploration and decompression should be considered.

53. What patient-related factors have a negative impact on results following a total knee arthroplasty?
Total knee arthroplasty is technically difficult after high tibial osteotomies, and the results are not as good as routine primary total knee replacements. Diabetics and patients with rheumatoid arthritis are at an increased risk for infection. Patients on Workmen’s Compensation do not do as well as others. The worst results are seen in obese men with osteoarthritis who are less than 60 years of age at the time of surgery (10-year survival rate of total knee arthroplasty: 37%).

54. How long does pain last after total knee arthroplasty?
This is extremely variable. Each patient needs to be managed individually. In general, pain management can be summarized as follows:
1-2 days postoperatively-Patients will have significant pain, and most need intravenous or intramuscular narcotic analgesia. Most patients can distinguish between postoperative pain and their preoperative arthritic pain. New management protocols are being developed to minimize this pain.
3 days postoperatively-The pain is usually controlled with oral analgesics.
2-3 weeks postoperatively-Some patients continue to require analgesics, whereas others may be weaned off their medications.
It can take up to 6 months to a year before the patient feels that the knee is fully recovered.

55. What is the weight-bearing status immediately after total knee arthroplasty?
There are different protocols, and it is important to discuss this with the operating physician. In the most common situation, when cement is used to fix both the femoral and tibial components, the patient are routinely allowed to bear weight as tolerated. Rarely, fixation requires bony ingrowth and then partial weight bearing may be utilized.

56. What other operative factors govern postoperative rehabilitation?
It is important to consider the operative approach when determining the weight-bearing status and the range of motion (ROM) that will be permitted. In some difficult cases the surgeon may need to osteotomize the tibial tubercle or cut the extensor mechanism to gain adequate exposure. In these instances, the rehabilitation protocol needs to be modified to allow the bone and muscle to heal.

57. Do all patients need thromboembolic event prophylaxis after total knee arthroplasty?
All patients should receive some type of thromboembolic event prophylaxis postoperatively. This prophylaxis has been shown to decrease the incidence of deep venous thrombosis and/or fatal pulmonary embolism. However, there is controversy over the best regimens, which include mechanical efforts, early rehabilitation efforts and pharmacological agent methods. Different pharmacological regimens include aspirin, warfarin (Coumadin) and low-molecular-weight heparin. Mechanical efforts include sequential pneumatic compression devices. Aspirin may also be combined with hypotensive epidural anesthesia.

58. What is the benefit of continuous passive motion (CPM) machines?
Although CPM may improve the amount of flexion a patient is able to attain initially, there is no evidence of any long-term benefit. Most surgeons do not use these machines in their rehabilitation protocols.

59.What is a knee manipulation and when should it be considered after a total knee arthroplasty?
There are no strict rules but usually if the patient has only 700 of flexion by 14 days postoperatively or less than 900 by 6 weeks manipulation of the knee should be considered.

60. What is the most reliable predictor of the range of motion a patient will have after total knee arthroplasty?
The best predictor of range of motion (ROM) after knee arthroplasty is preoperatively ROM. Thus, the better the ROM before surgery, the better it will be after surgery. On average, patients can achieve 105-1300 of flexion. At least 900 of flexion is desired for a good outcome, and this should be obtained within the first 2 weeks after surgery.

61. Outline a rehabilitation program for the patient with a total knee replacement.

Schedule Rehab Program
Day of surgery Deep breathing exercise, active ankle ROM
Postop day 1 Lower limb isometric exercises (quadriceps, hamstrings and gluteal sets), passive and active ROM exercises
Postop day 2 Active assisted ROM
Postop day 3 Progressive isotonic and isometric knee and hip muscle strengthening
  Concentrate on terminal knee extension through active knee extension exercises

62. What muscles should be targeted after total knee arthroplasty?
The quadriceps muscles are significantly weaker after total knee arthroplasty. This is, in part, related to the exposure required. Tourniquet and ischemic time also may play a part in muscular weakness. The quadriceps is important for stability during the stance phase of gait. Isometric strengthening and active ROM should begin immediately after surgery and be continued for the first 6 weeks. Resisted isokinetic or isotonic strengthening should be added. Other muscles that should be strengthened after total knee arthroplasties include the hamstrings, gastrosoleus, and ankle dorsiflexors.

63. List the usual sequence of ambulatory aids after a total knee replacement.
Parallel bars in inpatient physical therapy
Crutches or a walker, depending on patient stability and comfort
One crutch or cane
Most patients do not require assistive devices by 6 to 12 weeks postoperatively

64. How should a patient ambulate stairs after a total knee arthroplasty?
When ascending the stairs, the patient should lead with the nonoperative leg followed by crutches and the operative limb, one step at a time. When descending the stairs, the patient should lead with crutches and the operative extremity, following by the nonoperative extremity.

65. What are the four goals of occupational therapy after total knee arthroplasty?
1. To reestablish basic activities of daily living (ADLs), with modifications that keep the patient’s range of motion within restrictions
2. To teach joint protection
3. To review and minimize the risks for falls
4. To provide equipment with training

66. How long is it before a patient will receive full benefit after total knee arthroplasty?
By 3 months postoperatively, patients usually have regained most of their strength and ROM. However, in difficult cases or revision surgery it may be up to 1 year before the patient receives full benefit from the procedure.

67. Can a patient return to sports after total knee arthroplasty?
Yes. It is recommended that they refrain from high-impact sports, such as running, singles tennis, and football because these may lead to greater wear of the prosthesis. Low-impact activities include golf, doubles tennis, walking, and riding a stationary cycle.

68. What is an "extensor lag"?
This refers to the inability to fully extend the knee actively, although passively full extension is possible. This results from lengthening of the extensor mechanism or weakening of the quadriceps. Component malposition may also produce this problem.

69. How does a flexion contracture differ from an extensor lag?
A knee with a flexion contracture cannot be fully extended wither actively or passively. This is due to a mechanical block of which there are numerous causes, including scarred posterior capsule or other soft tissue structures, including the hamstrings, or retained osteophytes that may cause structures to tighten and thus block full extension. Component malposition also can cause this problem.

70. What rehabilitation approach should be used to treat a stiff knee post knee arthroplasty?
The authors recommend a multi-modality approach which combines revising the joint, performing an arthrolysis and excising any adhesions present with a strict rehabilitation protocol. A customized device may also be used to gain extension or flexion when physical therapy alone failed (moderate intensity isometric sets of gluteal, quadriceps and ankle pumps, active assistive flexion and passive extension exercises, active exercise of the hamstring muscles to relax the quadriceps mechanism by reciprocal inhibition).

71. How does one test the stability of a total knee arthroplasty?
Medial/lateral (varus/valgus). The knee is stressed at 0degrees, 30degrees, 60degrees, and 90degrees of flexion. An opening of greater than 5degrees to varus and valgus stressing is considered excessive.
Anterior/posterior. The knee is tested with an anterior drawer throughout the ROM. The position of greatest instability is noted. Normally in a total knee arthroplasty there is 5-8 mm of displacement in this plane, because the anterior cruciate ligament is sacrificed during the procedure.


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Authored by :German A. Marulanda, M.D., Michael A. Mont, M.D., Thorsten M. Seyler, M.D., Michael E. Frey, M.D., and Charles Msika, M.D.

Reprinted by permission from : Physical Medicine and Rehabilitation Secrets 3’d Ed: O’Young,BJ,Young,MA,Stiens,SA (eds.)