INDEX

Types of total knee replacement (TKR)Introduction 1-3

Indications & Contraindications of TKR4

Types of total knee replacement prosthesis 5-19

Rehabilitation protocol20-22

Do’s & Dont’s post TKR23

Complications post TKR24-31

References32

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Total Knee Replacement

INTRODUCTION

Total knee replacement (TKR) surgery, also called knee arthroplasty, is one of the most successful elective surgeries done today. The surgery replaces severely damaged cartilage tissue with a metal or plastic prosthesis that duplicates the function of the knee joint. Since the 1970s, the technology and long-term success of knee replacement surgery has improved dramatically, providing relief to people with chronic, debilitating knee pain.

Unicompartmental (Partial) Knee Replacement

When the cartilage in one of the knee compartments has become damaged, surgeons may be able to replace just the damaged section (compartment) of the joint. This procedure is called a partial or unicompartmental knee replacement.

Although the incision is smaller with a partial replacement and hospitalization is usually only one night, long-term results may not be as good as with total knee replacement. In addition, future surgical procedures may be more difficult after partial replacement surgery.

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The ideal patient for partial knee replacement surgery is someone who has arthritis in only one section (compartment) of the knee and is not obese. Patients under age 60 with sedentary lifestyles may also be candidates.

Advantages of unicompartmental over tkr :

Shorter rehabilitation time Greater average postoperative range of motion Preservation of the proprioceptive function of the cruciate ligs

Bilateral Knee Replacement

If pain is experienced in both knees equally and X-rays indicate severe arthritis in both joints, bilateral knee replacement may be a option. This procedure replaces both knees at the same time, reducing the time spent in a rehabilitation center after surgery. Although not a unique surgical procedure, the operation is not as common as single-sided TKR or partial replacement surgery. Candidates for this procedure must be in good health and free of certain medical conditions, including heart or lung disease.

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Minimally Invasive Surgery

Traditionally, knee replacement surgery has required lengthy incisions and dissection through the tendons of the knee to gain access for the replacement. Minimally invasive techniques now allow surgeons to perform knee replacement surgery with smaller incisions, and more importantly, less soft-tissue dissection. Minimally invasive surgery can be much more difficult to perform, however, and it is not indicated for all patients. This procedure may not be appropriate for knees that have significant deformity (bowlegged or knock-kneed) or previous major surgery. An orthopedic surgeon will determine whether this procedure is appropriate.

Computer-Assisted Surgery

In addition to traditional surgery, orthopedic surgeons at Mayo Clinic use a computer-guided imaging system during total knee replacement surgery. This new technology, also called computer-assisted surgery (CAS), helps the surgeon align the artificial joint in the bone and may increase the long-term effectiveness of knee replacements, especially in difficult cases such as those involving knock knees or bowlegs.

During computer-assisted surgery, a model of the knee is developed using infrared cameras and electromagnetic devices. The contour of the knee is projected onto a monitor, and the image helps guide the surgeon's attachment of the artificial implant to the bone. CAS provides an internal view of the joint for more precise alignment of the implant, which may improve the long-term

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success of the total knee replacement.replacement and computer-assisted surgery; four to six days following bilateral knee replacement; and overnight for a partial knee replacement.

INDICATIONS :

Tricompartmental knee replacement Severe arthritis wiyh or without significant deformity Older patients with more sedentary life style Younger patients who have limited function because of systemic

arthritis with multiple joint involvement Rheumatoid arthritis Osteonecrosis with subchondral collapse of a femoral condyle Chondrocalcinosis Pseudogout

Unicompartmental knee replacement Unicompartmental disease Elderly thin individual Unicompartmental disease Young patients Unicompartmental disease

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CONTRAINDICATIONS FOR TKR :

ABSOLUTE :

Recent or current joint infection – unless carrying out an infected revision

Sepsis or systeminc infection Neuropathic arthropathy Painful solid knee fusion

RELATIVE :

Severe osteoporosis Debilitated poor health Non functioning extensor mechanism Painless, well functioning arthrodesis Significant peripheral vascular disease Skin conditions such as PSORIASIS within the operated field Morbid obesityRecurrent urinary tract infection

TOTAL KNEE REPLACEMENT PROSTHESIS

There is no such total knee joint prosthesis that can mimic the complicated forms of surfaces of the knee joint and the "fuzzy biomechanics" of a healthy knee joint. Every total knee joint prosthesis is thus a compromise, that mimic only certain characteristics of the natural knee joint. The classification of total knee prostheses is equally "fuzzy".

Classification of   Total Knee Prostheses

Here follows an arbitrary classification of total knee prostheses. This classification is based on:

I.Amount much of the joint surface is replaced

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unicompartmental tricompartmental TKP 

II.Posterior cruciate ligament (PCL) state

PCL retained PCL removed   (" posterior stabilized")  TKP

III.Mobility of the polyethylene joint surface (bearing)

fixed polyethylene (PE) bearing mobile PE bearing TKP

I. Unicompartmental and tricompartmental   TKP

The normal knee joint has three chambers -compartments.

According to  how many of the three knee joint compartments  will be replaced with the kne joint device There are  two models of total knee prostheses, the one model replaces only one compartment of the knee joint, the other model replaces the whole (or almost) knee joint.         

1.  Unicompartmental total knee prosthesis :  

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Unicompartmental knee prostheses provide for replacement of only one knee joint compartment, i.e. the opposing joint surfaces of the femur and tibia, either on the inside or on the outside of the knee joint.

In other words, this is only a partial knee joint replacement.

Unicompartmental knee prosthesis   is used in knees where only one half (one compartment) of the joint is affected by the disease. In this picture the medial  compartment (inner part) of the knee joint has been replaced.

The unicompartmental knee prosthesis has two components.

The femoral component which replaces the joint surface of the femoral condyle is  a bent metallic plate with a slightly convex joint surface. The curvature of the bent plate imitates  the curvature of the natural femoral condyle.

The tibial component which replaces the tibial joint surface is an almost flat tibial plate which has semicircular surface and is fabricated from polyethylene. The polyethylene plate has often metal backing made from titanium.

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unicompatmental knee

A -side-view,   B - frontal view 

The polyethylene plate is either fixed to the metal backing plate by the manufacturer or it moves freely  on the polished surface of the metal

backing envelope.

This  later model is also called menisceal bearing unicondylar prosthesis. The polyethylene plate mimics the function of the meniscus in the healthy knee because it glides forwards and backwards on the polished plate during extension and flexion of the knee joint as does the natural meniscus.

Both components have pegs for better fixation to the skeleton.

2. Tricompartmental total knee prosthesis     

 Tricompartmental knee prostheses provides for replacement of all three knee joint compartments  (spaces), that is the replacement of whole joint surfaces of femur, tibia, and patella. This is a true total knee replacement.

Tricompartmental total knee prostheses provide for replacement of all three knee joint surfaces, including the patellar surface.

The surgeon, however, may decide not to replace the patellar surface.

The convex femoral component of a total knee prosthesis is a large plate bent to accommodate the curvatures of the femoral condyles.  The femoral component has  a large flange in front for contact with gliding patella.

The slightly concave tibial component is a plate made of a UHMW (ultra high molecular weight) polyethylene. The plate is often enclosed in a metallic   retainer (back-up). The metallic back-up helps to minimize the deformation of the polyethylene component under loads. The metallic back-up is often fabricated from Titanium.

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Oxford Uni-compartment knee

Also the patellar component (made of polyethylene) may have a metallic back-up.

The surfaces of the total knee components in contact with skeleton are provided with  pegs that improve the fixation of the components to the skeleton.

II. Posterior stabilized and PCL retained total knee

Posterior cruciate ligament (PCL) is an important structure that stabilizes the knee joint. In knee joints with severe osteoarthritis, this ligament is, however, often defective or absent.

Many surgeons believe that when the PCL is well functioning, it should be retained during the total knee replacement. For this purpose there are available PCL retaining Total knee prostheses.

Other surgeons believe that PCL cannot function well in a total knee prosthesis and should be always removed before the total knee is implanted. These surgeons also believe  that after removal of the PCL the surgeon should implant a special total knee prosthesis that simulates the function of the PCL.

There are thus available special posterior stabilized total knee prostheses for  operation of knee joints without PCL

The stabilization of the total  knee joint in these prostheses is achieved by a clever "cam and post" mechanism added to the prosthesis components. This mechanism replaces the function of the PCL.

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The function of the   cruciate ligaments

Inside a healthy knee joint  there are  two cruciate ligaments. These ligaments, thick as a pencil, are very important to keep the knee joint stable during bending. 

In knee joints affected by osteoarthritis and rheumatoid arthritis so much that they need replacement with a total knee prosthesis, the cruciate ligament that lies in front (anterior cruciate ligament) is usually  damaged by the disease process and without function. The surgeons remove the anterior cruciate ligament  routinely during the total knee replacement operation. Total knee prosthesis functions well even without  the anterior cruciate ligament.

After removal of the anterior cruciate ligament there remains the back   (posterior) cruciate ligament.   , usually at first sight still well preserved. The surgeon is now faced with a challenge: remove it or preserve it. That is an enigma.

The posterior cruciate ligament (PCL)

The posterior cruciate ligament (PCL) is a very important stabilizer of the normal knee joint.

The function of the posterior cruciate ligament (PCL) in a healthy knee joint

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When the normal knee joint bends the PCL pulls the upper part of the knee joint - the femoral condyles - backwards. The surgeons call this movement for "rollback".

(The cruciate ligaments are placed in the middle of the knee joint, so the schematic picture demonstrates a midline section through the knee joint).

Observations on  knee joints damaged at accidents demonstrate that  in the knee joint with damaged PCL the femoral condyle glides unrestricted forwards during bending. This uncontrolled glide causes severe instability of the knee joint.

In analogy with healthy knee joints, the majority of surgeons believe that PCL exercises similar "roll-back" function in a total knee joint.

The cruciate ligaments are placed in the middle of the knee joint, so the schematic picture demonstrates a midline section through the upper (femoral) component)

The theory goes as follows:

Stable total knee = total knee with retained posterior cruciate ligament (PCL)

(upper picture)

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In a total knee joint with retained PCL, the retained PCL   "rolls" the femoral component back when the total  knee joint bends. The total knee joint is thus stable. The wear of the polyethylene plate in a stable total knee is minimal.

It follows that retained PCL diminishes the wear of the polyethylene component and thus retention of a PCL diminishes the risk of loosening and failure of the total knee prosthesis.

Note that the tibial plate has a space for the PCL. This is a characteristic of a PCL-retaining total knee model.

Posterior stabilized total knee prostheses

 

In knee joints with fixed deformity (contracture) the PCL has become too short. During the total knee operation, the surgeon is then forced to strip or remove ("sacrifice") the PCL for correction of the deformity.

Moreover, in knee joints with more severe grades of osteoarthritis, the PCL are severely damaged and without function.

It is common belief among the surgeons that  knee joints with  damaged or absent  PCL cannot be replaced with the conventional total knee prosthesis, such replacement would produce an unstable total knee joint.

For replacement of knee joints without PCL there are thus available special

posterior stabilized total knee prostheses.

The stabilization of the total  knee joint in these prostheses is achieved by a clever "cam and post" mechanism added to the prosthesis components. This mechanism replaces the function of the PCL.

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The principle of a   posterior stabilized total knee prosthesis.

(Upper picture):  The femoral component has a transverse cam added to the backside of the prosthesis.

(Middle picture): The principle of the roll-back mechanism: The tibial polyethylene plate has a central polyethylene post placed on the middle of the plate. In the assembled total knee,  the cylindical cam comes against the post when the total knee bends. The post  then forces the cam backwards. 

(Lower picture) In the assembled total knee the tibial post sticks through an opening in the femoral component. When the prosthesis is in place, the post engages the transverse cam. The post and the cam make together a loose transverse hinge. As the total knee bends, this  hinge prevents the forwards glide of femoral component, the knee prosthesis rotates around this hinge instead. The post "rolls" the femoral component backwards.

In this way the posterior stabilized total knee replaces the function of the PCL.

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Posterior stabilized knee

There are patients with knee joints damaged by osteoarthritis that are without greater deformity and have a still retained PCL. Yet, many surgeons remove the still retained PCL and use a posterior stabilized total knee prosthesis for replacement of these knees too.

The reason is that the surgeon may have difficulty to balance the retained PCL with the new total joint prosthesis. The PCL is adapted to the natural tibial surface, and not to the tibial plate of the total knee prosthesis.

It is usually easier to

put a posterior stabilized total knee prosthesis in a knee joint with removed PCL and get a good stability of the new joint

than it is to put a conventional total knee prosthesis in a knee joint with retained PCL and get a stable total knee joint.

The advantages of a posterior stabilized total knees are:

1.technically easier to insert

2.easier removal of contractures

3.less pressure on the polyethylene plate

4.better range of motion in the previously stiff knee joint

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Disadvantages

1.with unbalanced soft tissues there is a risk of subluxation of the total knee joint

2.the post is made of polyethylene and wears off. "Severe" wear  of the post was found in about 30 % of all posterior stabilized total knees

3.failure of the posterior stabilized total knee caused by wear and damage of the polyethylene post was observed in 3 % of posterior stabilized total knees in a five year observation period according to some reports

4.more problem with kneecap (patella). In some reports   about 7% patellar fractures, but not all fractures needed treatment. (Thadani 2000)

III. CEMENTED   OR CEMENTLESS TKP

Everyone of these prostheses may be fixed to the skeleton

without  bone cement - cementless total knee prostheses, press fit fixation

or with bone cement cemented total knee prostheses.

1. The cementless total knee prosthesis

The surgeon pushes (blows, hammers) the prosthesis directly on the raw bone surfaces. The prosthesis is held in place by the elasticity of the bone tissue and by the friction between the surfaces of the skeleton and the prosthesis.

Total knee prostheses for cementless use have often porous coatings on the surfaces that are in contact with the skeleton. The porous coating partly enhances the friction of the prosthetic surfaces against the skeleton, partly it enhances the ingrowth of the host’s bone into the porous surface

In this way the porous coating improves the early fixation of the prosthesis and it produces  a lasting biologic fixation of the prosthesis to the skeleton later.

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The surfaces of the total knee components in contact with skeleton are provided  with stems that improve the fixation to the skeleton.

The patellar component that articulates with the metallic flange of the femoral component is also made of polyethylene, although it is convex. It has also  a metallic back-up.

(The stems are extra long because this is a  PCA revision prosthesis -

Howmedica)

The advantage of cementless fixation

       Absence of small particles of hard bone cement that occur between the total knee surfaces and increase polyethylene wear

The disadvantage of cementless fixation

Absence of seal of the space between the total knee prosthesis and the skeleton. In many statistics, cementless total knees demonstrated higher rates of loosening than the cemented prostheses.

2. The cemented total knee prosthesis:

The surgeon puts a thin layer of bone cement between the prosthetic components and the prepared skeleton surfaces. It depends on the surgeon if he uses the bone cement for fixation for all components of the total knee joint or if he/she uses the bone cement for fixation of  only some components.

When the self curing bone cement hardens, it fixes firmly the total knee components to the skeleton.

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The advantages of bone cement fixation:

The layer of bone cement will level off all unevenness of the cuts made in the skeleton.

The cement layer acts as an intermediate bumper between the very stiff metal of the components and the relatively soft skeleton.

The bone cement seals the interface between the prosthesis and the skeleton. The joint fluid with polyethylene wear particles cannot enter this space and provoke osteolysis

The disadvantages of bone cement fixation

Pressing the doughy bone cement into the marrow cavity of the thigh and shin bones may cause general circulatory disturbances

The bone cement layer ages, cracks, and after some time the bond between the prosthesis and the skeleton is lost .

IV. Mobile and fixed bearing of polyethylene joint surface

1. Fixed   (stabile) bearing total knee model

In the conventional total knee prosthesis the polyethylene component is  flat and fixed to the tibia (shinbone). This construction is called fixed   (stabile) bearing total knee model.

The difference lies in the design of the tibial component. In a fixed-knee prosthesis, the tibial component is topped with a flat metal piece that securely holds the polyethylene insert. When the knee moves, the femoral component glides across the polyethylene. Because the bumpy condyles at the end of the femur are not perfectly round, differing amounts of stress are put on the insert as the knee moves.

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ADVANTAGES :

Provides pain relief. Restores the motion of your knee. Improves quality of life. Good results in appropriate patients.

2. mobile bearing total knee joint

In the natural knee joint, the joint surfaces between tibia and femur are not conforming. Nature has placed a piece of triangular cartilage between these two joint surface, the meniscus,  which takes up and distributes the stresses evenly between the tibial and femoral joint condyles.

The menisci in the natural knee move quite a lot, and   the clever surgeons who discovered this fact put a moving piece of polyethylene to   replicate the Nature's  moving  interface system in their total knee joint prostheses.

Such a total knee model is called mobile bearing total knee joint .

In a mobile-bearing knee prosthesis, the polyethylene insert can rotate, which gives the knee implant a more natural contact between the femoral component and the polyethylene. Because the polyethylene can rotate with the femoral component, the contact between the two can be more evenly distributed, reducing stress on the implant. While the majority of knees implanted have traditionally been fixed-bearing, the mobile-bearing total knee replacement is quickly gaining surgeon acceptance.

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ADVANTAGES :

Provides pain relief. Restores the motion of your knee. Rotation similar to a normal knee. Reduces potential of early wear and loosening. Improves quality of life. more natural gait pattern

DISADVANTAGES

1.The polyethylene mobile plate has two wearing surfaces: one is the surface opposed to the femoral component, the other one is the surface opposed to the polished tibial tray. It is as yet uncertain, how much polyethylene particles this doubling of wearing surface produces.

2.The stability of the mobile polyethylene plate depends on well balanced ligaments and soft tissues around the new knee joint. The precise operation technique is essential for a good result.

3.The most frequent cause of failure in these prostheses is the accelerated wear, destruction, or dislocation of the mobile polyethylene plate in knees with ligament and soft tissues instability.

4.Some studies also claim that the range of movement of mobile bearing total knees is not better than the movement in the conventional stabile bearing total knees. (Archibeck 2002)

Indication for mobile bearing knee joint   prostheses

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The alleged advantages of mobile bearing knee joint prostheses are increased range of motion in the total knee and low wear of the polyethylene plate with lower risk for loosening. These advantages make this knee prosthesis suitable for young active patients.

LINKED   TOTAL KNEE   PROSTHESES

These total knee prostheses permit flexion and extension and  allow for a limited rotation. The linked total knee prostheses, however, prevent movements to both sides (abduction and adduction) of the knee joint. That is their purpose: to provide the total knee with intrinsic side stability.

The limited amount of rotation, that these prostheses allow , improves gait and decreases stresses on the bone -skeleton interface created by walk and other activities.  Thus, in contrast to the old true hinged total knees, the linked total knee prostheses have lover rates of complications.

These total knee joints are used  in knees with severe instability due to destruction of knee joint ligaments and severe bone loss.

Severe knee joint instability is often the result of a failed total knee surgery

Preoperative Rehabilitation• Ensure adequate strength of trunk and upper extremities for support during use of assistive devices• Instruction in use of walker/crutches/or cane to maintain desired postoperative weight bearing status (touchdown weight bearing for uncemented or hybrid replacements, weight bearing as tolerated for cemented replacements)• Review of post-operative exercises, bed mobility and transfers, use of continuous passive motion (CPM) machine as indicated per physician• General strengthening, flexibility, and aerobic conditioning While it seems reasonable to believe patients undergoing TKA would benefit from preoperative strengthening exercises, there is no evidence to support this assumption, either in improving functional outcome or shortening hospital stay (D’Lima et al., Rodgers et al.).However, a study by Jones et al showed that patients who have greater preoperative dysfunction may require more intensive physical therapy intervention after surgery because they are less likely to achieve similar functional outcomes to those of patients who have less preoperative

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POSTOPERATIVE REHABILITATIONNote: The following rehabilitation progression is a summary of the guidelines provided by Kisner and Colby. Refer to their publication to obtain further information regarding criteria to progress from one phase to the next, anticipated impairments and functional limitations, interventions, and goals.*Use of a CPM device is often initiated by the first day after surgery, per physician protocol. It has been suggested that CPM decreases postoperative pain, promotes wound healing, decreases incidence of deep venous thrombosis (DVT), and enables the patient to regain knee flexion more rapidly during early postoperative days. However, Kumar et al conducted a randomizedprospective study that found no statistically significant difference in range of motion gains using a CPM device versus active movement. Continuous passive motion units may be recommended as an adjunct to, not a replacement for, a supervised postoperative rehabilitation program.

Phase I: Maximum Protection: Weeks 1-2Goals:

Control postoperative swelling Minimize pain Knee ROM 0-90° Muscle strength 3/5-4/5 Ambulation with or without use of an assistive device Establish home exercise program

Intervention:• Passive range of motion (PROM)-CPM as indicated per physician• Ankle pumps to decrease risk of DVT• Bed mobility and transfers usually initiated 24-48 hours post-surgery, depending on surgical procedure and co-morbidities• Heel slides in supine or sitting to increase knee flexion• Muscle-setting exercises of the quadriceps, hamstrings, and hip adductors, possibly coupled with neuromuscular electrical stimulation• Assisted progressing to active straight-leg raises in supine, prone, and sidelying positions• Gravity-assisted knee extension in supine by periodically placing a towel roll under the ankle and leaving the knee unsupported• Gentle inferior and superior patellar glides• Neuromuscular inhibition techniques such as agonist-contraction techniques to decrease muscle guarding, particularly in the quadriceps, and increase knee flexion• Gentle stretches for the hamstrings, calf, and iliotibial band

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• Pain modulation modalities• Compressive wrap to control effusion• Gait training

Phase II: Moderate-Minimum Protection: Weeks 3-6Goals:

Diminish swelling and inflammation Increase ROM 0-115° or more Increased dynamic joint stability/full weight bearing per implant status Muscle strength 4/5-5/5 Return to functional activities Adhere to home exercise program

Intervention:• Interventions listed in Phase I• Patellar mobilizations• Tibiofemoral joint mobilization if appropriate and needed• Soft tissue mobilization to quadriceps or hamstrings myofascia• Incision mobilization after suture removal, when incision is clean and dry• Progressive passive stretches to hamstrings, gastrocnemius, soleus, quadriceps within a pain-free range• Stationary bike or peddler without resistance to increase flexion ROM• Pain-free progressive resisted exercises using ankle weights, theraband/tubing• Proprioceptive training such as weight shifting, tandem walking, lateral stepping over/around objects, obstacle courses, lower extremity proprioceptive neuromuscular facilitation (PNF), front and lateral step-ups, closed-kinetic chain activities• Closed-kinetic chain strengthening, such as ¼ squats, ¼ front lunges• Gait training as needed to decrease limp, wean off assistive device• Protected, progressive aerobic exercise, such as cycling without resistance, walking, or swimming

Phase III: Return to Activity: Week 6 and beyondGoals:

Progress ROM 0-115° as able, to a functional range for the patient Enhance strength and endurance and motor control of the involved limb Increase cardiovascular fitness Develop a maintenance program and educate patient on the importance of

adherence, including methods of joint protection

Intervention:• Continue interventions of previous phases; advance as appropriate

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• Implement exercises specific to functional tasks, such as transferring from sit-to-stand, lifting, carrying, push/pulling, squat/crouching, return to work tasks, return to sport tasks• Improve cardiorespiratory and muscle endurance with activities such as bicycling

DO’S AND DONT’S POST TOTAL KNE REPLACEMENT

Allowed activities: Walking Slow dancing Stationary or non-stationary bicycle Bowling Golf Low impact aerobics Croquet Swimming Shuffleboard Horseshoes

Allowed activities with some experience: Hiking (mild to moderate) Rowing

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Cross Country skiing Stationary skiing (Nordic Trac) Faster walking Tennis (non-competitive) Certain weight machines Ice skating

Activities not recommended: Handball Squash Rock climbing Soccer Singles Tennis Volleyball Football Gymnastics Lacrosse Hockey Basketball Jogging Running

Probably not recommended: Inline skating Downhill skiing

SYSTEMIC or GENERAL   COMPLICATIONS     AFTER   TOTAL   JOINT   REPLACEMENT

1. Heart infarct

Myocardial infarction occurs as a postoperative complication mainly in aged patients with previous heart disease or high blood pressure. The risk for this complication is very high in patients who have had heart infarct within six months before the artificial joint operation. The prevention is by careful preoperative screening for diseases that predispose for this complication.

2. Disturbance of the stomach and bowels function

Upset stomach or temporary disturbance of bowel passage after major artificial joint replacement operation may occur in up to 1% of all operations. With standard treatment (no food by mouth, intravenous nutrition) this complication resolves within days without further problems.

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3. Retention of urine

Retention of urine may occur both in male and female patients, more often after the spinal or epidural anesthesia. In a male patient the latent prostate obstruction may cause full-blown urine retention after operation. (If you have prostate problems, they should be dealt with before your total joint surgery.)

The treatment of urinary retention is by inserting an urinary bladder catheter to provide free passage for urine. Inserting the catheter after surgery is 1) painful, and 2) it may induce bacteria into the urinary system and cause a urinary tract infection. There is always an increased risk that these bacteria may spread into the recently operated artificial joint.

To prevent this situation, the surgeons insert routinely urinary catheters to all patients already during anesthesia, so that the insertion is pain-free. At the same time the newly operated artificial joint is covered by prophylactic antibiotics.

The catheters are usually removed on the second postoperative day, the removal is not painful. 

4. Postoperative confusion

A mild form of postoperative confusion may occur after general anesthesia, more often in aged patients. Risk factors are high age, deficiency of B vitamins, and "intake of alcohol on regular basis". On the other hand, it is astonishing to see old patients, tormented by painful joints and in deep depression, to literally blossom up after a successful total joint surgery. 

5. Mortality after total joint replacement operations

Total joint replacement is Major Surgery, and as with all Major Surgery there is a certain risk for deadly complications. If you are scared by all rumors, you should know that also the non-operative treatment of joint arthritis has its risks, some of them lethal. These risks are low compared with the risks for surgical treatment of joint disease, but they are present.

Statistics showed for example, that one out of every 1000 patients treated with NSAID developed bleeding gastric ulcer .Ten percent of patients with this complication died, a mortality rate of 1 / 10 000. For comparison, the thirty-day mortality rate after total hip surgery is nowadays 15 /10 000 (Parvizi,  2001).

The patients often wonder if they will make it through the operation. To allay your subconscious fears, here follow some optimistic facts about one unpleasant issue, the risk of death after an artificial joint operation.

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Most deaths occurring early after the total joint operations have been caused either by pulmonary embolus or by myocardial infarction in aged patients.

Unanimous statistics demonstrate that the death rates after total joint operations have been steadily diminishing thanks to the introduction of new operation techniques and improved anesthesia care.

The risk of death  has been 0,9 % in the 1970's a it has dropped to 0,1 % in the 1990's total hip and knee operations ( Sharrock NE 1995; Parvizi ,  2001).

There is also another positive message: patients operated on with artificial hip and knee joints live longer then do the people in the general population. (Lie ,  2000) Five years after a total hip or knee operation, 89% of patients were still alive whereas only 81% of the people in the general population of equal age were still alive.

The important systemic complications after a hip or knee replacement operation and their frequency are apparent in the Table.

 

 

FREQUENCY OF SOME SYSTEMIC COMPLICATIONS

Complication Frequency of complication (min - max)

Heart infarct 0,06% - 1,4%

Pulmonary emboli 1 - 6%

. Bowel obstruction 1 - 2%

Retention of urine 0,8% - 35%

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Confusion 0 - 5 % ?

 

OTHER   COMPLICATIONS of   TOTAL KNEE SURGERY

1. Loosening

of the components is the most common cause of failure of all types of total knee prostheses. Most often loosens the tibial component, followed by patellar component and femoral component. The loosening is a continuous process causing increasing discomfort.

The loosening rate of total knee prostheses is about one percent per year. That means that after 10 years 10 % of all patients with a total knee joint will have their total knee prostheses failed by loosening and exchanged.

If the patient experiences  increasing pain and stiffness in the loose total knee, the surgeon usually recommends revision operation. The discussion is still ongoing whether it suffices witch exchange of the loose component only, or whether the whole total knee prosthesis should be exchanged.

 

2. Instability of the total knee joint

has occurred in between 1 to 6 % of all total knee joints. Patient may just feel that the knee totters a little, in severe case of instability the patient just doesn’t dare to put weight on the unstable knee.

Uncorrected major knee joint instability will put excessive stress on total knee components and will eventually cause prosthetic loosening and destruction of the whole total knee prosthesis.

In most instances treatment is by use of walking aids, simple knee braces, and more extensive ankle -knee braces (orthosis). Surgical tightening of the soft tissues around the prosthesis have usually not been effective in stabilizing the total knee.

An alternative operation is to exchange the polyethylene liner - put a higher liner in. This will tighten the slack soft tissues

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If the instability is severe, the surgeon has the option remove the old unstable total knee prosthesis and put in a more constrained model of the total knee prosthesis.

3. Fractures around the total knee prosthesis

Such fractures usually occur after relatively minor injuries. Patients with "softer" bones, such as patients with rheumatoid arthritis, are at greater risk for these fractures. More commonly these fractures occur in the femoral shaft at the tip of the stem of the femoral component.The patient feels pain above the fracture site and the X-ray pictures then show the fracture.

Statistics show that these fractures occur in about 0,1% of all total knee prostheses (Furnes 2002) . The majority of these fractures can be managed by braces, only displaced fractures need operative treatment.

4. Patellar problems

Patellar problems comprise the largest number of complications after total knee replacement and have been reported in from 6 to 30 % of all total knee replacements.

The patient  with patellar problems has pain in front of his / her new total knee.

In a total knee joint where the surgeon did not replace the patella, the anterior knee pain  not seldom leads to additional operation with replacement of the patellar joint surface. But this additional replacement of patella does not always stop the pain

In a total knee joint where the surgeon replaced the patella already at the first operation, the patient may feel pain, clunking and instability of the replaced patella.

The cause of the pain is the fact that no total knee prosthesis model can imitate the complicated track that the patella follows during the extension and flexion of the normal knee joint.

All models of total knee prostheses force the patella to follow a straight track during the knee movement, which leads to increased wear of the patella and faulty tension in the soft tissue that keep the patella in the right track.

This mechanical mismatch causes subluxation , dislocation, and fracture of the patella, loosening of the patellar component, damage of the patellar component, and pain of uncertain origin.

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The treatment of patellar problems in a total knee is difficult.

For an unstable patella, the surgeon may try to balance the soft tissues around the patella. Most often such an operation implies making cuts in the soft tissues that force the patella back on the right track.

Destructed patellar components must be exchanged.

5. Patellar clunk syndrome

Some patients feel a painful clunk in front of their total knees when they bend the knee between 30 and 45 degrees. Sometimes the patient cannot move the knee beyond this range.

The cause is a soft tissue lump that forms on the joint capsule just above the patella. At 30 - 45 degrees of flexion, the lump catches the anterior flange of the femoral component, causes pain, and blocks further movement.

The treatment is by removal of the lump. It may be done by arthroscopic (key hole) surgery.

6. Increasing rigidity of the total knee joint

If, in about two weeks, you will not achieve 90 degrees of flexion in your new knee, your surgeon might suspect that scar tissue has formed in your knee and hinders the movement. The surgeon might recommend a manipulation of your new knee joint in narcosis. You would be put to sleep and the surgeon will passively bend your knee to 90 degrees or more if possible. This forcible bending should break down the scar tissue that has been forming in your new knee.

The manipulation must be done carefully because there is always risk of a skeletal fracture.

Statistics show that at risk are patients with second operation in their knees and patients with diabetes.

7. Swollen total knee joint

Transient swelling of the total knee joint after too much activity is not uncommon. It will disappear without specific treatment.

Lasting swelling of the total knee joint together with pain may by a sign of

increased wear of the polyethylene components

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infection of the total knee joint.

The surgeon usually takes a  sample of the joint fluid for bacteriological examination. This is done by a puncture of the joint with a fine needle; with proper technique the puncture should not be painful.

The treatment then depends on the condition that produced the swelling.

The damaged polyethylene components must be exchanged

The infection must be  treated accordingly (see the chapter Wound infection)

8. Component breakage

occurs as breakage of polyethylene components, mainly tibial,   in about 0,1 % of all total knees.  It is due by the   excessive pressure put on these components.  Breakage of metallic components of the total knee prosthesis is exceedingly rare nowadays.

The signs are pain, stiffness, and often also swelling of the total knee. Special X-ray pictures may disclose the damage.

The treatment is by exchange of the damaged components. At operation, the surgeon may discover that the damage is more widespread then suspected before the revision operation and whole total knee joint must be exchanged.

9. Injury of the peroneal nerve

is reported in 0,3% to 4% of all total knee operations (Idusuyi 1996)

The patient feels tingling and numbness in the foot, in cases of more serious damage the patient cannot stretch the foot. These symptoms are caused by the damage of the peroneal nerve. If you notice these symptoms notice immediately your doctor.

The peroneal nerve crosses the knee joint on the outside. It lies there directly beneath the skin on the hard fibula bone (lesser shin bone) and can be damaged by direct pressure from outside by tight splints and dressings.

It is important that the knee after the operation is NOT rotated outward, lying on a brace or continuously moving machine.

It is important that there is no unpolstered rail in the brace or bed, coming in contact with the knee joint.

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It is important that  the patient who has a continuous postoperative pain relieving drop or epidural anesthesia is followed closely. These patients have impaired sensation, and cannot feel the pressure and numbness in the leg properly.

It is also suspected that correction of the   contracture of the knee joint during the total knee replacement may stretch the nerve too much and damage it.

Patients with rheumatoid arthritis are at higher risk to experience peroneal nerve damage after THR than other patients (Schinsky 2001)

If there is suspicion of nerve damage, all postoperative dressings must be immedialy cut and removed. The wound must be inspected to exclude accumulating blood pool (haematoma) that may exert pressure on the nerve.

In most cases all symptoms disappear after proper treatment. The patient is usually fitted with a protective brace, loose  dressings are applied,  the knee is slightly bent and physiotherapy is started. Some surgeons do also EMG evaluation of the muscles innervated by the peroneus nerve, other surgeons use the EMG examination only to follow the improvement.

Surgical revision of the nerve is rarely needed.

10. Pain in the scar

is not so rare. The pain occurs either spontaneously or when the patient touches the scar. Some patients feel a sensation of small "electrical shock" when touching the scar.

This phenomena is caused by damage to small branches of the main skin nerve (with the name nervus saphenus). The nerve lies on the inside of the knee and its branches cross the middle line of the knee. The cut through skin in midline damages some of these branches. Sometime the scar tissue around these branches then causes pain or "electricity shocks" when touching them.  In most cases this condition needs no treatment.

11. Damage of the vessels around the knee

is very rare. At risk are patients with known vascular disease and patients with previous operation on the knee.

The symptoms are intensive pain in a cold, pale, pulse- less leg. This situation demands an acute consult with the vascular surgeon to decide on further action.

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REFERENCES

1.Clinical orthopaedic rehabilitation, 2nd edition, by S. Brent Brotzman & kewin E wilk.

2. Turek’s orthopaedics , principles and their application , 6th edition ,by Stuart L. Weinstein & Joseph A. Buckwalter.

3.Therapeutic exercise foundation and techniques , 4th edition , by Kisner & Golby.

4.operative orthopaedics, by Campbell, 11th edition, volume 1.

5. Chapmans orthopaedic surgery, edition 3, volume 1, by Michael E Chapman.

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