Rehabilitation in the Postoperative Fractures and Arthritis of the Knee PDF

# Rehabilitation in the Postoperative Fractures and Arthritis of the Knee. ## 1. INTRODUCTION. - The postoperative rehabilitation of the knee is one of the major areas of intervention for physical therapists worldwide. - Considering factors such as the high incidence of sports and work-related inj...

# Rehabilitation in the Postoperative Fractures and Arthritis of the Knee. ## 1. INTRODUCTION. - The postoperative rehabilitation of the knee is one of the major areas of intervention for physical therapists worldwide. - Considering factors such as the high incidence of sports and work-related injuries, increasing rates of osteoarthritis and articular replacement surgery related to the aging population, high costs related to the need for revision surgery due to various postoperative complications, and the demand from patients to reverse the secondary problems of injury and surgical procedures to regain their functional level, it can be said that the physical therapist plays an important role in the evolution of all patients surgically treated for traumatic or degenerative knee pathologies. - The scientific evidence available today on postoperative rehabilitation for ligament reconstruction and total knee replacement surgeries has provided physical therapists with effective intervention guidelines that allow for the restoration of functional levels close to or identical to those presented by healthy subjects. - However, it is necessary to re-raise the problem that involves the lack of information available regarding the postoperative rehabilitation of patients who have suffered a fracture of the knee bones. - To better illustrate this difficulty, it is worth mentioning that combining the keywords "distal femur fractures", "proximal tibia" or "tibial plateau fractures" and "patella fractures", with "rehabilitation" or "physical therapy" in the Pubmed database, yields no more than five results in the period between the years 2000 and 2013. ## 2. BIOMECANICAL FACTORS IN KNEE REHABILITATION. - Understanding the physiology of the movement of the articular surfaces, as well as the compressive forces to which they are subjected during load application, is essential for developing appropriate clinical reasoning when using manual therapies and therapeutic exercises in patients with knee fractures. - It is evident that most of the data provided below will not be applicable to patients with TKA (and partly, to patients with UKA), except for patients without patellar resurfacing, in which case the forces crossing the patellofemoral joint should be considered. - When making a decision regarding the indication of therapeutic exercises in patients with a specific orthopedic condition of the knee, the compressive forces applied to the femorotibial and patellofemoral joints, as well as the forces acting on the ligaments and menisci, must be considered. - The correct interpretation of these factors, in combination with the broadest possible knowledge about the patient's condition and the state of their articular tissues, will provide the foundation for the best choice of therapeutic interventions without jeopardizing their clinical evolution. ### 2.1. The femorotibial joint - The femorotibial joint is classically described as a hinge joint with two planes of motion: - **Flexion-extension**, with an amplitude of 120°-160° depending on the position of the hip, and **axial rotation**. - Axial rotation is null in extension due to the locking that occurs between the lateral ligaments and the cruciate ligaments, whereas at 90° of flexion, the tibia can perform 40° of external rotation and 30° of internal rotation. - During extension in closed kinetic chain (CCC), the femoral condyles perform a motion of anterior roll, increasing the distance of the posterior cruciate ligament (PCL) insertions. - Due to its inelastic nature, the ligament pulls the condyles backwards inducing a posterior slide on the tibial plateaus. The last 30° of extension also results in an internal rotation motion of the femur. - During extension in open kinetic chain (OCC), the tibial plateaus roll and slide anteriorly on the femoral condyles. In the last 30° of extension, the motion is accompanied by an external rotation of the tibia [(Fig. 1)]. - During flexion in CCC, the femoral condyles roll posteriorly, increasing the distance from the anterior cruciate ligament (ACL) insertions which in turn creates an anterior slide of the condyles on the tibial plateaus. - This motion is associated with an external rotation of the femur at the beginning of flexion initiated by the popliteus muscle. - In OCC flexion, the plateaus roll and slide posteriorly, associated with an internal rotation for the first 30°. - Lesions of the cruciate ligaments alter the arthrokinematics, and produce abnormal translations of the tibiofemoral joint during flexion and extension. - These aberrant movements can damage the menisci and the articular cartilage, leading to early degenerative changes in the knee. ### 2.2. The patellofemoral joint. - The patellofemoral joint is a reciprocal joint between the patella and the femur. - Its stability depends on the passive and active stabilizers surrounding the knee. - The medial patellofemoral ligament is the primary restraint to lateral translation of the patella, contributing 60% of the restrictive force. - The medial meniscopatellar ligament and the medial retinaculum contribute 13% and 10% of the remaining force, respectively. - The passive restraints to medial translation are the structures that form the superficial and deep fibers of the lateral retinaculum. - The superficial layer is made of fibers from vastus lateralis and the iliotibial band. - The deep layer is made up of the lateral patellofemoral ligament, the deep fibers of the iliotibial band, and the lateral tibiopatellar ligament. - The tightness of the retinacular structures can lead to abnormal patellofemoral kinematics associated with lateral compression. - The quadriceps muscle represents the primary dynamic restraint. - Historically, the treatment of patellofemoral pain has focused on strengthening the vastus medialis obliquus (VMO). - However, there is no conclusive evidence that selective recruitment of the VMO can be achieved through specific exercises. - It is likely that a comprehensive quadriceps strengthening program can be successful in the treatment of patellofemoral pain. - Only part of the patella articulates with the femoral trochlea during flexo-extension. - There is no contact between the two bones in extension. - At 20° of flexion, initial contact occurs between the inferior pole of the patella and the trochlea. - The contact area moves proximally so that at 90° of flexion, the superior pole of the patella contacts the trochlea. - After 90°, the patella enters the intercondylar fossa and the quadriceps tendon articulates with the femoral trochlea. - It is not until 135° of flexion that the odd facet contacts the medial femoral condyle [(Fig. 2)]. ### 2.3. Exercise effects - Rehabilitation exercises used in the treatment of the knee include movements in open and closed kinetic chains. - Some relevant points to bear in mind when prescribing therapeutic exercises are described next: - **Open kinetic chain (OCC) extension** produces an isolated contraction of the quadriceps, which results in anterior translation of the tibia. - The ACL is responsible for 85% of the resistance to this motion, with the secondary restraints being the posterior capsule and the menisci. - Beynnon (1995) showed that the ACL stretches by 2.8% during an open kinetic chain extension without weight, while applying a load of 45N at ankle level resulted in 3.8% ACL stretch. - In both cases, peak stretching occurred at 10° of flexion. - Similarly, isometric quadriceps contractions with the knee at 15° and 30° of flexion produced stress of 4.4% and 2.7%, respectively, whereas no LCA strain was registered at 60° and 90° of flexion. - Therefore, open kinetic chain extension exercises at angles below 45° may have harmful effects on an ACL graft or on the secondary restraints of anterior tibial translation in patients with torn ACL. - **Patellofemoral reaction force (FRPF)** is a measure of the compression of the patella against the femur, and varies depending on the exercise modality and angle of flexion. - During open kinetic chain extension, the flexion moment increases as the moment arm of the patella decreases, which results in a higher demand for force to extend the knee, especially near full extension (this explains the "extension lag" in the presence of quadriceps weakness). - Reilly and Martens (1972) obtained an FRPF of 1.4 times body weight at 36° of flexion, which was halved at full extension. - This explains why straight leg raise and short arc extension exercises (20° to 0°) produce maximal quadriceps stress with minimal patellofemoral stress. - **Hungerford and Barry (1979) and Steinkamp (1993) reported the effects of open-chain extension on FRPF in the 90° to 0° flexo-extension range**. - Studies have shown that the patellofemoral forces are lower than 90° of flexion, and that as the knee extends, the FRPF increases and the contact area decreases. - This results in an increase in contact stress until approximately 20°, when the patella no longer contacts the trochlea. - Therefore, exercises may be better tolerated by the patellofemoral joint in the 90° to 50° and 20° to 0° ranges. - **Closed kinetic chain (CCC) flexion** is the result of an isolated contraction of the hamstrings, which produces a posterior translation of the tibia and stress on the PCL. - Grood (1988) analyzed the magnitude of this translation in cadaveric knees without PCL, demonstrating minimal posterior translation with the knee in extension and increasing progressively with flexion, reaching 11.4 mm at 90°. - Lutz (1993) found that isometric closed kinetic chain flexion produced increases in posterior translation forces between 30° and 90°. - These studies show that closed kinetic chain CCC-flexion exercises generate stress on the PCL and should be used carefully following PCL injury or surgery. - Such exercises reinforce the concept that closed kinetic chain flexion does not place stress on the ACL. - **CCC exercises** result in a simultaneous synchronized motion of all joints. - The most commonly used closed chain exercise is the squat, which results in simultaneous flexion and extension of the ankle, knee, and hip. - The movement can be performed with bodyweight, a barbell, or a machine. - The squat can be done as half squat (where the thighs are parallel to the floor) or full squat (where the subject descends until the posterior surfaces of the thigh and leg make contact). - One point of controversy regarding the squat exercise is the optimal angle of descent and the associated risk of damage to the knee structures. - The following points are from Escamilla's (2001) systematic review: - The squat exercise subjects the knee to both translational (shearing) and compression forces. - Excessive shearing forces can damage the cruciate ligaments, and excessive compressive forces can be detrimental to the articular cartilages and menisci. - Stress on the ACL during a squat between 0° and 60° is minimal, making the exercise safe for both healthy knees and those with reconstructed ACL. - Furthermore, studies have shown that performing the movement with greater hip flexion and anterior trunk inclination reduces stress on the ACL, due to increased hamstring activity. - Generally, studies agree that stress on the ACL increases with greater flexion angles. - The combination of internal and external rotation of the femur and tibia during flexo - extension is supported by both the cruciate ligaments and the collateral ligaments. - Cadaveric and human studies have shown that tension on the lateral ligaments increases during a deep squat, resulting in stress of approximately 8% on the medial collateral ligament (MCL) and 13% on the lateral collateral ligament (LCL). - Deep flexion affects the menisci. - As the femur rotates externally during descent, the menisci are forced to slide posteriorly, causing the posterior horns to be compressed between the femoral and tibial condyles. - Internal femur rotation at the beginning of ascent can force the posterior horn of the medial meniscus to move towards the center of the joint, which can lead to meniscal tear. - Internal femur rotation also places torsional stress on the MCL, and because it inserts into the medial meniscus, it can lead to menisco - capsular tear or avulsion. - Some of this meniscus can displace towards the center of the joint and lock the knee in a flexed position, preventing complete extension. - The anterior translation forces and, therefore, stress on the ACL also increase significantly when the knee excessively moves forward, and when the subject performs a bouncing motion at the end of a deep squat. - Similarly, the posterior translation force and stress on the PCL increases significantly when the squat angle exceeds 50° to 60°. - One study reported forces on the PCL of 0-500N between 0° and 50° of flexion, increasing to 2700N between 50° and 100°. - Therefore, individuals with injured PCL and/or reconstructed PCL should avoid squatting beyond 50°. - With regards to the position of the feet, there is no difference in compressive and shearing forces between placing the feet parallel and in 30° of external rotation. - Placing the feet apart in a "narrow stance" (the distance between the feet is at the level of the distance between, the anterior superior iliac spines) generates lower compressive forces compared to a "wide stance" (twice the distance between the anterior superior iliac spines). - Other studies have shown that fatigue, as well as performing the squat at a higher speed, increases anterior translation forces, leading to a higher risk of damage to the native or grafted ACL. - Performing a squat in a press machine generates shearing forces 30-40% higher compared to the standard barbell squat. - Therefore, the potential for injury to the cruciate ligaments is higher during the squat in the press machine, and even higher when it is performed at high speeds. - Forces at the level of the patellar and quadriceps tendon are also affected by the angle of flexion. - Compressive forces between the quadriceps tendon and the intercondylar fossa reach 6000N at 130° of flexion, decreasing rapidly to 1750N at 90°, and practically reaching 0N at 60° of flexion. - One study demonstrated similar behavior of the forces at the level of the patellar tendon, which reached 6000N at 130° of flexion and decreased to 2000N with the knee at 30° of flexion. - Studies have also shown that tensile forces increase significantly when the descent takes place at high speed. - Therefore, performing the squat slowly and at angles below 90° minimizes both the tendofemoral compressive forces and the tensile forces at the level of the quadriceps and patellar tendons. - Tibiofemoral compressive forces also increase as the angle of flexion increases, reaching 8000N at 130° of flexion and decreasing slowly to approximately 5500N at 60°. At 30° of flexion, compressive forces were 3500N. - While compression has been recognized as a means to stimulate chondrocyte biosynthesis, caution should be taken when prescribing deep squats for both healthy subjects and those with chondral lesions of the knee. - There are 3 forces acting on the patella during the squat: - 1) the quadriceps tendon force. - 2) the patellar tendon force. - 3) the femoropatellar compressive force [(Fig. 2)]. - Mathematically, compressive force is maximal at greater angles of flexion due to the increased components of the quadriceps and patellar tendon forces in the direction of femoropatellar compression. - Excessive compressive forces, or those of lower magnitude but applied repeatedly, can contribute to patellofemoral degenerative changes and the development of conditions such as chondromalacia and osteoarthritis. - Patellofemoral compressive forces increase as the knee flexes, showing the highest rate of increase between 50° and 80°. - These forces reach their maximum values approximately at 90-100° of flexion. - From these angles, the compressive forces remain relatively constant. - Individuals with signs of patellofemoral pain should avoid deep squats. However, performing the movement in the functional range of 50° of flexion may be appropriate for these patients as it produces mild to moderate compressive loads. - In relation to the position of the feet, no functional differences have been observed in regards to patellofemoral compressive forces and muscle activity in the different quadriceps bellies, gastrocnemius, and hamstrings when comparing feet in external, internal, and neutral rotation. - Therefore, contrary to the common belief, there is no evidence that rotation increases the activity of the vastus medialis. - On the other hand, if the goal is to reduce patellofemoral compressive forces, it is preferable to use a narrow stance compared to a wide stance. ## 3. NEUROPHYSIOLOGICAL FACTORS IN KNEE REHABILITATION. - The knee represents a synchronized system made up of the human biological tissues. - The components act in a coordinated manner as a biological transmission unit that receives, transmits, and dissipates loads between the femur, tibia, patella, and fibula. - Data currently available indicate that, in addition to their mechanical function, the intraarticular components of the knee are sensitive. - This means that they generate neurosensory signals that reach the spinal and suprasinal levels of the central nervous system. - These signals ultimately result in conscious perception capability - Dye and Vaupel (1998) used arthroscopy to directly palpate these structures in the absence of intraarticular anesthesia, in order to record the subjective experience and establish a neurosensory map of the knee. - During arthroscopic palpation, the subjects attempted verbally, to describe as accurately as possible, the location of the knee from which the sensation originated on a 0-4 scale: -0 - No sensation; -1 - Conscious non-painful awareness; -2 - Slight discomfort; - 3 - Moderate discomfort; - 4 - Severe pain. - The record was modified with an "A" if the spatial localization was accurate, or with a "B" if the sensation was poorly localized. - Finally, the sensation was plotted in a two-dimensional map [(Fig. 3)]. - The penetration of the instrument through the anterior synovium and the infrapatellar fat, anaesthetized, produced severe pain. - Conversely, palpation of the articular cartilage of the patella at the level of the central crest and medial and lateral facets did not produce any sensation whatsoever (despite the fact that the subject had grade II or III chondromalacia). - The odd facet evoked a score of 1B. - The suprapatellar recess, the capsule, and the retinacula generated sensations of type 3A and 4A. - Palpation of the anterior and posterior cruciate ligaments resulted in sensations of 1B and 2B in the mid-region which increased up to 3B and 4B at the level of the insertions. - The menisci showed scores of 1B in the inner region, and 2B and 3B at the capsular margins and at the level of the anterior and posterior horns. - Palpation of the femoral condyle articular cartilages, the trochlea, and the tibial plateaus produced sensations of 1B-2B. - The study provides evidence that the anterior synovium and the infrapatellar fat, the capsule, and the retinacula, are highly innervated structures that could be the origin of symptoms in patients with anterior knee pain, independently of the primary cause. ## 3.1. CONCEPT OF ARTHROGENIC MUSCLE INHIBITION ### 3.1.1 Generalities - The knee contains two main classes of sensory receptors. - Those innervated by large-diameter myelinated afferent fibers (Afferent Group II) are stimulated by stimuli such as stretching and pressure, are highly sensitive, and have a very low firing threshold. - These include Ruffini endings, Pacinian corpuscles, and receptors similar to the Golgi tendon organs. - The proportion of these receptors in the knee is relatively small. - The vast majority of afferent fibers that innervate the knee correspond to high threshold receptors, and include slightly myelinated fibers (Group III) or unmyelinated fibers (Group IV). - In humans, about 7o% of the fibers of the articular branch of the tibial nerve, the main sensitive contribution to the knee, are unmyelinated afferents. - Group III and IV afferents terminate at free nerve endings, which respond to strong mechanical, thermal, and chemical stimuli. - Their primary function seems to be nociception, informing of actual or potential damage to the articular structures. - However, some of the free nerve endings can also act as mechanoreceptors, activated by passive non-painful movements and local mechanical stimulation of the knee. - Marked weakness of the quadriceps is typically observed after an injury or knee surgery, or in patients with osteoarthritis. - This is partly due to muscle atrophy, but also partly due to neural inhibition secondary to altered sensory function of the knee structures. - This phenomenon is known as *arthrogeic muscle inhibition (AMI)* which prevents complete activation of the muscle. ### 3.1.2 Factors Triggering AMI. - Several factors have been identified as triggering increased afferent discharge in patients with arthritis, injury, or knee surgery. - These include: - **Edema**. Edema is often a persistent condition in certain arthritic pathologies, and it can also persist for a long time after the acute phase of an articular injury or surgery. - It has been demonstrated that edema increases the discharge of Group II fibers, even in the absence of pain, due to increased intraarticular pressure. - Knee edema causes significant AMI of the quadriceps, even in the absence of factors such as inflammation, pain, or structural damage. - **Inflammation**. Although edema has the potential to trigger severe AMI, it is not always a direct trigger of this phenomenon. - In patients with acute knee injury, torque increased by 8.8Nm immediately after aspiration, but increased by 21Nm after 14 days of corticosteroid injection. - These findings suggest that there are other mechanisms involved in AMI that are are not related to increased pressure. - **Studies in animals have shown that inflammation induces potent, lasting changes in the sensitivity of the free nerve endings innervated by Group III and IV fibers, a process known as "peripheral sensitization."**. - The activation threshold of these receptors decreases, so that normal articular movement or innocuous mechanical stimulation of the articular structures triggers substantial discharge of these fibers. - In addition, these receptors show an increased response to noxious mechanical stimuli and an increase in spontaneous discharge when the joint is in a static position. - Finally, the inflammatory process can awaken silent receptors which, usually do not respond to innocuous or noxious stimuli but, in the presence of inflammation, decrease their threshold and respond to a broad range of mechanical stimuli. - Collectively, these mechanisms significantly increase the discharge from Group III and IV fibers to the central nervous system. - Since Group III and IV fibers have a nociceptive function, it can be expected that inflammation increases pain with increased afferent discharge. - However, it is important to remember that AMI can occur in the absence of pain. - While knee pain can be associated with quadriceps inhibition, it appears to be a poor indicator of the severity of the AMI. - Therefore, reducing pain does not necessarily reduce muscle inhibition. - **Joint instability.** Laxity and joint instability can alter the activation of the sensory receptors in the knee. - Damage to stabilizing structures causes increased translation of the articular surfaces, which can increase the activation of nociceptors and mechanoreceptors involved in signaling the joint motion limits. - Animal studies have shown that surgically resecting the ACL increased afferent discharge during common movements, whereas reconstruction with a graft partly reversed these changes. - However, other studies suggest that while afferent activity tends to normalize with surgery, there may still be certain differences 9 to 18 months after ACL reconstruction. - **Damage to the articular receptors.** Trauma that produces damage of the articular structures, can simultaneously damage sensory endings in these tissues, reducing the afferent input from receptors. - Normally, AMI is associated with excessive sensory discharge. - However, there is a competition between the different articular afferent inputs, inhibiting and exciting the motor neurons of the quadriceps, and sometimes the inhibition may be due to the loss of sensory information from the articular receptors. ### 3.1.3 Presentation and Evolution - AMI occurs commonly as a result of a broad range of pathologies that present with quadriceps weakness, including osteoarthritis, rheumatoid arthritis, anterior knee pain, patellar contusion, patellar El material de estudio cuenta con el registro de la propiedad intelectual de los autores. Dirección Nacional del Derecho del Autor. Nº 5102126 18 ==End of OCR for page 18== - rupture and ACL reconstruction, meniscal lesion, meniscectomy, and in patients treated for TKA. - In a study of patients with meniscectomy (Shakespeare et al.), the EMG amplitude of the quadriceps was reduced to 50-70% in the first hours, followed by worsening to 80-90% over the next 24 hours. - By day 3 and 4, inhibition was still 70-80%, and after 15 days it decreased significantly but persisted with a magnitude of 30-50%. - Similarly, AMI increases in the first 3 to 4 weeks after knee replacement surgery. - Mizner (2005) concluded that arthrogeic inhibition contributes almost twice as much as atrophy to the quadriceps weakness observed after this procedure. - There is evidence that suggests that AMI usually remits with time. - Machner et al. (2002) found a 10% decrease in inhibition of muscle at 18 months after unicompartmental knee replacement, compared to pre-surgical values. - Similarly, Berth et al. (2002) reported that in patients with knee arthroplasty, AMI decreased from 15% before surgery to 6% at 33 months. - However, clear reductions in AMI are not always observed in the medium term (approximately 6 months). - Breath et al. (2007) observed that in patients undergoing knee arthroplasty, AMI remained at levels of 15-20% from pre-surgery to 3 and 6 months. - It is important to note that, frequently, AMI occurs bilaterally after injury or surgery on one knee. - This has been demonstrated in patients with ACL tear, extensive traumatic knee injuries, anterior knee pain, after ACL reconstruction surgery, meniscectomy, and total knee replacement. - AMI in the contralateral limb usually is less severe but, similar to the inhibition on the injured side, may persist for more than 4 years after joint injury. - In patients with knee osteoarthritis, researchers found no significant relationship between age and severity of AMI. - However, a relationship between gender and inhibition has been reported, with it being more severe in women than in men. - Based on the available literature, it can be stated that AMI is more severe in the first few days after joint injury, tends to decrease slightly to reach a plateau at 6 months, and decreases slowly over the long term (18-33 months). - Furthermore, it has been demonstrated to occur bilaterally and to be directly associated with the female sex in patients with knee osteoarthritis. ## 4. REHABILITATION: FOCUS ON THE APPROACH TO THE PATIENT WITH TKA. - As previously stated in the introduction, the literature regarding rehabilitation after conservative orthopedic treatment or fracture repair of the knee is scarce. - The problem is even wider when considering that the literature on rehabilitation after arthroscopic procedures or osteotomy for knee osteoarthritis is also limited. - In contrast, there is a growing body of information regarding different aspects of TKA rehabilitation, covering pre- and postoperative evaluation, functional exercise, neuromuscular electrical stimulation, functional scales, etc. - The importance of pre-intervention therapeutic factors based on biomechanical and neurophysiological factors, in conjunction with what was outlined in the “Fractures and Osteoarthritis of the Knee” chapter regarding temporal parameters for weight bearing and mobilization in patients with fractures, provides a theoretical framework for the application of evidence-based interventions within a clinically reasoned approach. - We will now analyze evaluation and treatment practices in the rehabilitation of patients with TKA, acknowledging the strategies of pre- and postoperative evaluation and treatment during the pre-surgical period and during the El material de estudio cuenta con el registro de la propiedad intelectual de los autores. Dirección Nacional del Derecho del Autor. Nº 5102126 9 ==End of OCR for page 9== - postoperative period. - Since a large portion of the analysis and general patient management focuses on the compromise of the extensor apparatus and on the restrictions in mobility and function, most of the content discussed will be applicable to the treatment of patients who underwent knee surgery for osteoarthritis through another procedure, or to those with a knee fracture. ## 5.1. GENERALITIES. - The goal of knee replacement surgery is to provide the patient with a pain-free, well-aligned, and stable joint whose function resembles that of a normal knee as closely as possible. - Specific information about the surgery that can impact rehabilitation includes the type of fixation, the type and extent of bone and soft tissue resection, whether or not patellar resurfacing was performed, and the type and extent of pre-surgical malalignment. - Since the arthroplasty components are almost universally cemented, full weight bearing can begin immediately. - Patients who did not undergo patellar resurfacing may experience anterior knee pain and joint effusions for several weeks. - Implants that retain the PCL have been shown to allow for greater range of flexion. - However, there is no evidence regarding the differences in long-term articular mobility between prostheses that retain the PCL and those that sacrifice it. - To be successful, the implants must be appropriately designed, the bony resection must be properly oriented, and the periarticular soft tissues must be adequately balanced. - Current implants appear to optimize ROM and patellar alignment, and to provide a pain-free joint even for strenuous activities. - Modern prostheses maximize longevity, especially in younger, active patients. - Currently, many surgeons believe that properly placed modern implants will last over 20 years. - Bone resection accuracy is being progressively improved by the use of manual instrumentation. - In addition, the recent introduction of computer - assisted surgical techniques has resulted in even more accurate bone resections. - The severe degenerative process in patients with severe osteoarthritis results in marked angular deformities (varus, valgus, flexion, rotation) and a degenerative process associated with both contracture and elongation of the periarticular tissues. - It is critically important that these deformities be addressed properly during the surgical procedure. - Once surgery is complete, the knee must be stable and show appropriate balance in the mediolateral and anteroposterior planes, in flexion and extension. - Furthermore, the patella must glide adequately over the femoral trochlea of the femoral component. - Achieving this goal may require release of shortened structures (e.g., collateral ligaments, retinacula) or tightening of the elongated structures. - Bony resection and soft tissue balancing can impact rehabilitation. - For example, patients with severe valgus deformity may experience increased pain on the lateral side of the knee due to release. - In addition, they may show ankle valgus or foot pronation requiring the prescription of orthotics to prevent recurrence of the deformity. - Currently, it is believed that the more precise the bony resection, the less the need for soft tissue balancing, and the reduction in procedures involving release is associated with less postoperative pain and faster recovery. - In 2002, the National Institutes of Health (NIH) issued a statement of consensus regarding the state of science related to TKA. - The authors suggested that “the use of rehabilitation services is perhaps the least studied aspect of the perioperative management of TKA patients…and there is no evidence to support the widespread use of any one rehabilitation intervention preoperatively or postoperatively.” - However, over the past decade, various authors have proposed new therapeutic approaches that have demonstrated superior results over the long term after TKA, compared to conventional approaches. ## 5.2. IMPORTANCE OF THE PRE-SURGICAL APPROACH: **"PREHABILITATION."** - While TKA is effective in relieving pain, decreased muscle strength may persist for years after surgery. - A large percentage of patients with knee replacement show quadriceps weakness compared to the unaffected leg and to individuals of a similar age. - This predisposes older adults to falls and reduces their ability to perform functional tasks. - Preoperative measurement of strength, functional capacity, and pain in the knee has been shown to be a significant predictor of TKA outcomes. - Some studies examining the effects of pre-surgical exercises on postoperative recovery in patients with knee replacement have reported limited benefits (Weidenhielm 1993, Rodgers 1998, Beaupre 2004. D'Lima 1996). - However, these studies included small sample sizes, had limited statistical power, inadequate exposure to the exercises, and lacked the specificity of training necessary to impact outcomes. - In contrast, more recent reports suggest more encouraging results. - Rooks (2006) highlighted that a 6-week exercise program can safely improve pre-surgical functional level and muscle strength in patients undergoing total hip and knee replacement. - Their theory states that pre-habilitation improves functional capacity before a stressful event. - Pre-habilitation is defined as the improvement of functional capacity of an individual through physical activity to withstand a stressful event. - It suggests that pre-surgical exercise has a positive impact on pain, functional capacity, and quadriceps strength [(Fig. 4)]. - Numerous authors have studied the effects of exercise and other forms of intervention in patients with knee osteoarthritis, and have reported favorable results in terms of pain, strength, and functional level. - Supporters of pre-habilitation believe that several weeks of a therapeutic exercise program can attenuate the effects of surgery on strength and function. - Swank et al. (2011) assigned 71 patients who were candidates for TKA to a basic care group (UC) and to a basic care and exercise group (UC+EX). - Individuals in the UC group continued their normal activities, while individuals in the exercise group followed a comprehensive program that included progressive resistance training with elastic bands, flexibility, and step training 3 times per week for 48 weeks prior to surgery. - Measurements were taken before randomization to study groups (T1) and one week before surgery (T2). - The authors found that individuals in the UC+EX group showed significant improvements in the sit-to-stand test in 30 seconds, stair climbing time, and peak torque in affected knee extension. - The exercise program was effective in reducing the asymmetry of strength relative to the unaffected leg and, in addition, in reducing pain. - Despite the evidence supporting the use of pre-habilitation to improve strength before surgery, it is necessary to question how this practice affects the postoperative course of these patients, as some researchers have reported persistence of asymmetry of strength up to 12 months after surgery (Felson 2000, Rossi 2006). - Topp et al. (2009) studied the effect of pre-habilitation on strength and functional levels after TKA in 54 patients with knee osteoarthritis. - The patients were assigned to a control group and a pre-habilitation group, and evaluations were performed before randomization (T1) and one week before surgery (T2), and after 1 and 3 months after surgery (T1 and T3, respectively). - Compared to El material de estudio cuenta con el registro de la propiedad intelectual de los autores. Dirección Nacional del Derecho del Autor. N° 5102126 11 ==End of OCR for page 11== - the control group, patients who underwent pre-habilitation showed: - Improved performance on the sit-to-stand test at T2 and T3. - Improvements in the sit-to-stand test, climbing a flight of stairs and descending a flight of stairs at T4, but not on the 6-minute walk test. - Significant decrease in all pain measures. - Increased quadriceps strength in the operated and non-operated knee. - While the benefits of using neuromuscular electrical neuromuscular stimulation (EENM) in patients with knee osteoarthritis are known, its effect on strength and function during the pre-habilitation period has not been defined. - Walls et al. (2010) evaluated the usefulness of a pre-surgical, home-based program of EENM in 9 patients with knee osteoarthritis, compared to a control group that only performed exercises (n=5). - The electro-stimulation device was used for 20 min per day every 2 days during the first 2 weeks, then sessions were performed 5 days per week for