Orthopedics

Stiffness After TKR: How to Avoid Repeat Surgery

Edwin P. Su, MD; Sherwin L. Su, MD; Alejandro Gonzalez Della Valle, MD

  • Orthopedics. 2010;33(9)
  • Posted September 1, 2010

Abstract

Stiffness after total knee replacement (TKR) is a frustrating complication that has many possible causes. Although the definition of stiffness has changed over the years, most would agree that flexion <75° and a 15° lack of extension constitutes stiffness. The management of this potentially unsatisfying situation begins preoperatively with guidance of the patient's expectations; it is well-known that preoperative stiffness is strongly correlated with postoperative lack of motion. At the time of surgery, osteophytes must be removed and the components properly sized and aligned and rotated. Soft tissue balancing must be attained in both the flexion/extension and varus/valgus planes. One must avoid overstuffing the tibiofemoral and/or patellofemoral compartments with an inadequate bone resection. Despite these surgical measures and adequate pain control and rehabilitation, certain patients will continue to frustrate our best efforts. These patients likely have a biological predisposition for formation of scar tissue. Other potential causes for the stiff TKR include complex regional pain syndrome or joint infection. Close follow-up of a patient's progress is crucial for the success in return of range of motion. Should motion plateau early in the recovery phase, the patient should be evaluated for manipulation under anesthesia. The results of reoperations for a stiff TKR are variable due to the multiple etiologies. A clear cause of stiffness such as component malposition, malrotation, or overstuffing of the joint has a greater chance of regaining motion than arthrofibrosis without a clear cause. Although surgical treatment with open arthrolysis, isolated component, or complete revision can be used to improve TKR motion, results have been variable and additional procedures are often necessary.

Stiffness is one of the most common complications following TKR, causing frustration to both the surgeon and the patient. Pariente et al1 examined their experience between 1997 and 2003, including >5000 TKRs, and found that approximately 7% of them met their definition of stiffness. Of this 7%, 75% underwent successful manipulation under anesthesia; however, 15% of knees undergoing manipulation remained stiff and subsequently required revision surgery. Thus, 1% of these primary TKRs experienced stiffness to the degree that revision surgery was necessary.

Yercan et al2 examined >1100 TKRs and found a 5.3% rate of stiffness. Of the patients having manipulation, approximately 20% failed and required revision surgery, again giving a 1% incidence of revision.

The flexion requirements for certain activities of daily living have been well-documented.3,4 It is interesting to note how the definition of stiffness has changed over time. In 1990, Nicholls and Dorr5 defined stiffness after TKR as flexion <45° and a flexion contracture of 20°. In 2002, Christensen et al6 defined stiffness as a flexion of <75°. In 2006, Yercan et al2 defined the stiff knee as one that flexed <95° and had a flexion contracture of 10°. It is safe to say that both surgeons and patients have greater expectations for their knee replacements >20 years ago.7

The disability of walking with a flexion contracture has been well researched.8 Walking with a flexed knee gait requires constant quadriceps activation, leading to an increased energy consumption and greater fatigue. Without sufficient flexion, activities of daily living such as stair climbing, rising from a chair, and tying one’s own shoelaces can be challenging. Although the traditional teaching is that a stiff knee should not be painful, patients who are fighting a nonfunctional range of motion will have pain during these activities.

We believe that the disability from a lack of full extension is much greater than from a lack of flexion. Thus it is important to monitor the ability to fully extend the knee both intraoperatively and postoperatively. Furthermore, we are more likely to…

Abstract

Stiffness after total knee replacement (TKR) is a frustrating complication that has many possible causes. Although the definition of stiffness has changed over the years, most would agree that flexion <75° and a 15° lack of extension constitutes stiffness. The management of this potentially unsatisfying situation begins preoperatively with guidance of the patient's expectations; it is well-known that preoperative stiffness is strongly correlated with postoperative lack of motion. At the time of surgery, osteophytes must be removed and the components properly sized and aligned and rotated. Soft tissue balancing must be attained in both the flexion/extension and varus/valgus planes. One must avoid overstuffing the tibiofemoral and/or patellofemoral compartments with an inadequate bone resection. Despite these surgical measures and adequate pain control and rehabilitation, certain patients will continue to frustrate our best efforts. These patients likely have a biological predisposition for formation of scar tissue. Other potential causes for the stiff TKR include complex regional pain syndrome or joint infection. Close follow-up of a patient's progress is crucial for the success in return of range of motion. Should motion plateau early in the recovery phase, the patient should be evaluated for manipulation under anesthesia. The results of reoperations for a stiff TKR are variable due to the multiple etiologies. A clear cause of stiffness such as component malposition, malrotation, or overstuffing of the joint has a greater chance of regaining motion than arthrofibrosis without a clear cause. Although surgical treatment with open arthrolysis, isolated component, or complete revision can be used to improve TKR motion, results have been variable and additional procedures are often necessary.

Stiffness is one of the most common complications following TKR, causing frustration to both the surgeon and the patient. Pariente et al1 examined their experience between 1997 and 2003, including >5000 TKRs, and found that approximately 7% of them met their definition of stiffness. Of this 7%, 75% underwent successful manipulation under anesthesia; however, 15% of knees undergoing manipulation remained stiff and subsequently required revision surgery. Thus, 1% of these primary TKRs experienced stiffness to the degree that revision surgery was necessary.

Yercan et al2 examined >1100 TKRs and found a 5.3% rate of stiffness. Of the patients having manipulation, approximately 20% failed and required revision surgery, again giving a 1% incidence of revision.

Definition of Stiffness

The flexion requirements for certain activities of daily living have been well-documented.3,4 It is interesting to note how the definition of stiffness has changed over time. In 1990, Nicholls and Dorr5 defined stiffness after TKR as flexion <45° and a flexion contracture of 20°. In 2002, Christensen et al6 defined stiffness as a flexion of <75°. In 2006, Yercan et al2 defined the stiff knee as one that flexed <95° and had a flexion contracture of 10°. It is safe to say that both surgeons and patients have greater expectations for their knee replacements >20 years ago.7

Functional Limitations

The disability of walking with a flexion contracture has been well researched.8 Walking with a flexed knee gait requires constant quadriceps activation, leading to an increased energy consumption and greater fatigue. Without sufficient flexion, activities of daily living such as stair climbing, rising from a chair, and tying one’s own shoelaces can be challenging. Although the traditional teaching is that a stiff knee should not be painful, patients who are fighting a nonfunctional range of motion will have pain during these activities.

We believe that the disability from a lack of full extension is much greater than from a lack of flexion. Thus it is important to monitor the ability to fully extend the knee both intraoperatively and postoperatively. Furthermore, we are more likely to intervene surgically if the patient has a flexion contracture due to the presence of a limp and difficulty walking.7

Causes

The etiology of stiffness after TKR is multifactorial and can be divided into preoperative, intraoperative, postoperative, and patient factors.

Preoperative

It has been well-documented that preoperative range of motion is the best predictor of postoperative range of motion.9,10 Thus, the treatment of stiffness after TKR must begin with the management of patient expectations. That is, the surgeon must counsel a patient preoperatively about their expected motion gain or loss. Most patients will gain approximately 10° to 15° from TKR, however, some hyperflexible patients will lose motion. In looking at the bell-shaped curve of preoperative range of motion (ROM), the postoperative curve will shift to a greater mean ROM, but also be with a smaller standard deviation. Patients beginning with greater preoperative ROM may therefore lose motion postoperatively. Berend11 presented data for a cruciate-retaining knee that demonstrated an average postoperative ROM of approximately 115° (Table 1). By examining patients with regard to their preoperative ROM, the average gain/loss of ROM postoperatively can be calculated, allowing for the management of expectations.

Table 1: Average Change in Postoperative Knee ROM

A history of prior surgery, particularly a high tibial osteotomy and the diagnosis of posttraumatic osteoarthritis has also been associated with stiffness post-TKR. Therefore, these patients should be aware that there is a greater incidence of postoperative stiffness when compared to a virgin osteoarthritic knee.

Intraoperative

Meticulous surgical technique is critical for the realization of good motion. The implants must be positioned properly with regard to the coronal and sagittal planes. The goal of tibial resection is to produce a cut bony surface perpendicular to the mechanical axis, with a few degrees of posterior slope. The aim of femoral resection is to recreate neutral mechanical limb alignment with 3° to 6° valgus, and 0° to 4° of flexion.

Figure 1 demonstrates a femoral component placed in excessive flexion, thereby limiting extension. The position of the implants relative to the joint line is also important. In general the amount of bone removed must equal the thickness of the implants minus any wear of bone from the arthritic process. This should position the joint line approximately 1 cm proximal to the fibular head, or 2 cm distal to the medial epicondyle. An inadequate tibial resection will cause overstuffing of the femorotibial joint and subsequent lack of motion. Figure 2 demonstrates a joint line that is 2 cm proximal to the fibular head, clearly indicating an inadequate tibial resection. The patellofemoral joint is also subject to overstuffing. An inadequate patellar resection, as shown in Figure 3, will result in a thick patellar bone-implant construct, causing tightness in flexion.

Figure 1: Femoral component placed in excessive flexion Figure 2: An inadequate tibial resection leads to overstuffing of the femorotibial space
Figure 1: Femoral component placed in excessive flexion, leading to a lack of extension. Figure 2: An inadequate tibial resection leads to overstuffing of the femorotibial space and elevation of the joint line.

Figure 3: Overstuffing the patellofemoral space will also limit motion
Figure 3: Overstuffing the patellofemoral space will also limit motion. Note the thickness of the patellar bone+button construct.

Soft tissue balancing also has a great effect on postoperative motion. If the collateral ligaments are not well balanced, the kinematics of the knee will suffer. For example, a varus knee left with medial collateral ligament tightness will not bend as well as a well-balanced knee. Surgical exposure, positioning of the implants relative to the coronal plane, and releases of contracted structures will influence the soft tissue component of a TKR.

Balancing the flexion and extension gaps is another important step in achieving a knee that can bend. Flexion and extension gaps should be equal to allow for the smooth transition from extension into flexion. These factors can be controlled independently by the amount of bone resected from the distal and posterior femur. Therefore, determining both the level of the distal femoral resection and the size of the femoral component are crucial. For a cruciate retaining knee, the tension in the posterior cruciate ligament (PCL) may also affect the balance of the flexion/extension gaps.12

Rotational malalignment will also affect motion by creating potential conflict with the soft tissues, femoral and tibial implants, and patellar and femoral implants. The femoral component must be aligned with the epicondylar axis to create a symmetric flexion space; the tibial component must be aligned with the middle one-third of the tibial tubercle to allow for good patellofemoral tracking. Furthermore, the femoral and tibial implants should be co-linear to ensure proper function of the post-cam mechanism with a posterior stabilized TKR.

Implant Considerations

The size of the femoral component may affect the flexion gap. Therefore, an array of sizes to match the native anatomy of the femur are essential; most modern systems have 6 to 8 sizes that allow for incremental sizing and reproduction of the posterior offset.

Implant geometry, particularly of the articular surfaces, will also affect kinematics within the context of soft tissue balancing and implant position. A more highly conforming articular surface will be less forgiving of implant malalignment. Furthermore, some implants are designed for “high-flexion.” This refers to the ability to allow a greater ROM prior to impingement as compared to the standard implant. However, clinical studies and meta-analyses comparing high-flexion with standard implants have not demonstrated any difference in ROM.13-15 Therefore, it is best to use these implants selectively in patients with a greater preoperative ROM so that the choice of implant does not limit ultimate ROM. If a patient has 140° of flexion preoperatively, the surgeon can select an implant that will allow similar motion postoperatively.

Similarly, the amount of implant constraint can affect knee motion. The more constrained the post/box mechanism is, the more impact that soft tissue imbalance, rotational malalignment, or coronal malposition will have.

The effectiveness of postoperative analgesia will have an effect on motion after TKR. Many surgeons and anesthesiologists have adopted a regimen of pre-emptive analgesia, regional nerve blocks, and local infiltration of anesthetics to achieve more effective pain control. The more complete the control of postoperative pain, the greater the patient’s ability to participate in physical therapy.

Patient participation in postoperative therapy is another critical factor in the success of attaining motion. It can be difficult to assess a patient’s motivation in the course of preoperative evaluation. Nevertheless, it is an important aspect that must be understood as part of the counseling process; the surgeon and patient will enter into a cooperative agreement to obtain the best possible result.

The quality of postoperative therapy will affect the results of TKR. It is necessary to begin the process of obtaining flexion and extension immediately postoperatively. Should a patient not participate in an intensive physical therapy program following the surgery, scar tissue that limits the amount of motion, will form.

Complex regional pain syndrome should be considered when the pain is out of proportion to the physical findings and/or no objective data exist to explain the lack of motion postoperatively. The knee may appear slightly erythematous and will be hyperalgesic to the touch. If complex regional pain syndrome is suspected, a diagnostic/therapeutic sympathetic block may aid in pain control.

Occult infection is another consideration when dealing with stiffness post-TKR. A low-grade infection may cause underlying inflammation and pain that will limit the patient’s ability to participate in therapy. Systemic laboratory indicators and a joint aspiration are helpful to rule out this potential cause.

Arthrofibrosis

Despite a surgeon’s best efforts and surgical prowess, some patients will continue to develop frustrating stiffness post-TKR. There is likely a genetic component of scar tissue formation that has yet to be identified. These patients will, no matter what, continue to develop arthrofibrosis as part of their healing process, despite flawless technical execution of their TKR.

Treatment Options

In any patient at risk for stiffness (ie, the multiply operated knee, the hyperflexible, and the patient with a prior history of stiffness), close follow-up should be performed. As the treatment options diminish with the chronicity of the condition, these at-risk patients should be seen sooner after TKR. Whereas in general, we see patients 6 weeks after TKR, we will see the at-risk patient at 3 to 4 weeks postoperatively. A trajectory of their motion gains can be ascertained at an early date, potentially preparing the patient for an intervention.

Manipulation Under Anesthesia

Manipulation under anesthesia is the first tool in the armamentarium of dealing with postoperative TKR stiffness. It can be effective in managing limited flexion; however, it is less successful in addressing a flexion contracture.

The literature indicates that manipulation under anesthesia is successful in the treatment of 80% of cases of post-TKR stiffness; however 20% will require repeat manipulation, and 10% will ultimately undergo surgery for stiffness.2

The complications of manipulation under anesthesia include periprosthetic fracture and extensor mechanism disruption; the likelihood of these complications is more likely as the chronicity of the condition increases. Therefore most surgeons advocate manipulation under anesthesia within 3 months of TKR to optimize the risk/benefit ratio.

We perform manipulation under anesthesia with the use of an epidural catheter. Gentle, controlled pressure is placed on the tibia close to the joint line, to mitigate the risk of tibial fracture. The breakage of intra-articular adhesions can be palpated and heard; the manipulation is performed until there is no further breakage of scar tissue, which usually requires a few attempts. Manipulation for an extension deficit is more difficult and less controlled; the risk of supracondylar femur fracture is too great with the application of excessive force.

Initiation of intensive physical therapy is important to lock in the gains of the manipulation under anesthesia. We have also found that pictures of the achieved ROM are a good motivating factor for the patient and therapist, giving them a goal to work toward.

Arthroscopic Lysis of Adhesions & Manipulation Under Anesthesia

The concept behind arthroscopic lysis of adhesions and subsequent manipulation under anesthesia is similar to that in the shoulder—debulk the amount of intra-articular adhesions and perform manipulation under anesthesia in a more controlled setting. In principle, it makes sense; however, in practice, it is difficult to imagine that an arthroscopic procedure is able to remove sufficient fibrotic tissue to make a significant difference.

In certain isolated situations, however, arthroscopic lysis of adhesions may have greater success; namely that of the tight PCL in a cruciate-retaining knee. Williams et al16 have demonstrated success in 8 of 9 cruciate retaining knees, gaining a mean of 30· flexion and 3· extension.

Open Arthrolysis & Polyethylene Insert Exchange

An open procedure will allow greater access to remove fibrotic, intra-articular scar tissue (Figure 4). Exchange of the polyethylene insert will allow access to the posterior portion of the knee joint, as well as the ability to release the posterior capsule from the tibia or femur. In doing so, flexion contractures can be remedied. If a thinner polyethylene insert is available, then both the flexion and extension gaps can be decreased.

Figure 4A:  Dense, fibrotic scar tissue removed Figure 4B: Histologic examination reveals densely packed collagen fibers
Figure 4: Dense, fibrotic scar tissue removed at the time of open arthrolysis (A). Histologic examination reveals densely packed collagen fibers (B).

The caveat of this procedure is that the component position and alignment must be perfect for this to be effective. Furthermore, there is a possibility of creating joint instability with the debridement; therefore additional levels of constraint should be available.

Revision Total Knee Replacement

A full revision is the most powerful intervention that a surgeon can perform, essentially creating a “blank slate.” Removing the existing prosthesis allows complete access to remove scar tissue, reconstituting the natural recesses within the joint. With the new implantation, a surgeon can correct rotation, sagittal and coronal alignment, and perform soft tissue balancing. Additionally, a surgeon may select the implant most conducive to allowing motion, or to decrease/increase levels of constraint as desired.

Isolated component revision may also be performed if the surgeon wishes to minimize the invasiveness of the procedure. In general, we find an isolated femoral revision to give more options for correction of motion, due to the ability to independently adjust the flexion and extension spaces.

Results

In reviewing the literature over the period between 1987 and 2009, we found 18 peer-reviewed studies on the surgical intervention for stiffness. Four were for arthroscopic treatment, 7 for open arthrolysis and poly insert exchange, and 7 for revision (Table 2). The results are variable, owing to the multifactorial nature of post-TKR stiffness. The results of revision TKR have the lowest incidence of failure of recurrence; therefore, a revision gives the best chances of gaining motion.7

Table 2: Review of Literature Comparing Results of Different Surgical Strategies for Stiffness of TKR

Conclusion

Stiffness is one of the most frequent complications of TKR. It is multifactorial with some elements out of the surgeon’s control. Prevention is paramount, with careful patient selection, preoperative counseling, and meticulous surgical technique. In approximately 80% of cases of stiffness, manipulation under anesthesia will successfully address the problem. In the situations in which surgery is necessary to remediate stiffness, correction of flexion contractures generally have more satisfying functional results. Revision TKR offers a greater chance of success than arthroscopic debridement or open arthrolysis and polyethylene insert exchange.

References

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Authors

Drs Su (Edwin) and Della Valle are from the Hospital for Special Surgery, New York, New York; and Dr Su (Sherwin) is from St Joseph’s Hospital, Wayne, New Jersey.

Dr Su (Edwin) is a consultant for Smith & Nephew, Inc. Drs Su (Sherwin) and Della Valle have no relevant financial relationships to disclose.

Presented at Current Concepts in Joint Replacement 2009 Winter Meeting; December 9-12, 2009; Orlando, Florida.

Correspondence should be addressed to: Edwin P. Su, MD, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021 (sue@hss.edu).

doi: 10.3928/01477447-20100722-48

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