Management of stiffness following total knee arthroplasty

The Effect of Postoperative Sleeping Position on Knee Extension and Range of Motion Following Primary Total Knee Arthroplasty

Total knee arthroplasty (TKA) is an orthopaedic operation that improves quality of life and reduces pain in patients with disabling arthritis of the knee. One commonly recognized complication is flexion contracture of the knee. Early physical therapy helps prevent flexion contracture and improve range of motion (ROM) postoperatively. This study evaluated postoperative sleeping position and its effect on terminal knee extension and ROM following primary TKA. We hypothesized that patients who slept in the supine position would achieve earlier knee extension and greater ROM when compared to those in the lateral recumbent position. A total of 150 consecutive primary TKAs were performed by a single surgeon (J.M.C.) from April 2014 to December 2014. The data were collected prospectively to determine preoperative ROM, postoperative ROM, and sleeping position. Mean postoperative terminal extension ROM at 1 month was 2.9 degrees in the supine group versus 6.0 degrees (p< .001) in the lateral group. No significant demographic differences between the two groups at baseline were found. Our results demonstrate that sleeping position affects initial postoperative terminal extension, however, not overall ROM. We found a statistically significant difference in extension when comparing patients in the supine versus lateral group. Patients who slept in the lateral position lacked 6 degrees of extension which is greater than the 5 degrees needed for normal gait mechanics. Those in the supine group lacked 2.9 degrees of extension, allowing for normal gait mechanics. This study identifies an easy, effective means of increasing patients initial ability to achieve knee extension and satisfaction following TKA.

Early outcomes of a novel bicruciate-retaining knee system: a 2-year minimum retrospective cohort study

INTRODUCTION

Bicruciate retaining (BCR) total knee arthroplasty (TKA) was designed to simulate natural knee kinematics and improve proprioception by retaining both the ACL and PCL. While the prospect of the design appears favorable to patients, previous designs have demonstrated modest survivorship rates compared to traditional designs. This study aims to report the early functional outcomes and implant survivorship of a novel BCR design.

MATERIALS AND METHODS

A multi-center, retrospective study was conducted identifying BCR TKA patients from 2016 to 2017. Patient demographics, quality outcomes, and post-operative complications were collected. A Kaplan-Meier analysis was used to evaluate revision-free survival.

RESULTS

One-hundred thirty-three patients with a mean follow-up time of 2.35 ± 0.25 years (range: 2.00-2.87 years) were identified. Patients receiving BCR TKA were, on average, 61.46 ± 9.27 years-old, obese (BMI = 31.80 ± 6.01 kg/m²), predominantly white (71.4%), and female (69.9%). The device was most often implanted using standard instruments (85.7%) compared to computer-assisted navigation (13.5%). Average length-of-stay was 1.77 ± 0.97 days. Six patients had a reoperation; three (2.5%) full revisions occurred for: infection (n = 1), arthrofibrosis (n = 1), and ACL rupture (n = 1); one (0.8%) tibial revision occurred for: arthrofibrosis; two (1.5%) liner exchanges occurred for: infection (n = 1) and arthrofibrosis (n = 1). Kaplan-Meier survivorship analysis of cumulative failure at 2-year showed a survival rate of 96.2% (95% confidence interval, 91.2-98.4%) for all-cause reoperation, 97.3% (91.6-99.1%) for aseptic revision, and 100% for mechanical failure.

CONCLUSION

Survivorship was 96.2% for all-cause reoperation, 97.3% for aseptic revision, and 100% for mechanical implant failure at 2-years. This novel BCR TKA demonstrated no implant-related complications and excellent survivorship outcomes over 2 years with comparable revision rates to those previously reported in the literature.

Mid-term outcomes of posterior capsular release for fixed flexed deformity after total knee arthroplasty

Fixed flexion deformity also called flexion contracture is relatively rare, but a very demanding functional limitation that both surgeons and patients may have to deal with. The purpose of the present study was to evaluate the functional outcomes after posteromedial capsular release in case of fixed flexed deformity > 15 o . Between June 2011 and November 2018, 15 patients (6 males and 9 females) were treated with open posterior capsular release through medial approach for fixed flexion deformity of the knee > 15 o and prospectively followed with a minimum follow-up of 2 years. Primary outcome was knee extension measured with a manual goniometer and secondary outcome treatment related complications. All patients reported inability to walk and clinical semiology of pain and swelling. The mean age of the study population at surgery was 61.7 years with a mean BMI of 30.9 kg/m2. Complete data were recorded for all patients. Statistically significant improvement was found in clinical and functional assessment tools analyzed from baseline to the latest follow-up (p<0.05). More precisely, the mean postoperative fixed flexion deformity was decreased from 23.57 o to 2.86 o . No adverse effect or major complications were recorded during follow-up. Posterior open release via posteromedial was shown to be an efficient and safe salvage procedure to deal with persistent fixed flexion deformity of more than 15 o following TKA at two years follow-up. However, future studies with a higher number of participants and longer follow-up should be conducted to validate our data.

Home physiotherapy with vs. without supervision of physiotherapist for assessing manipulation under anaesthesia after total knee arthroplasty

Abstract

The aim of this retrospective cohort study was to compare home physiotherapy with or without supervision of physiotherapist for assessing manipulation under anaesthesia after total knee arthroplasty.

Methods

A total of 900 patients (including 810 females and 90 males) who had undergone total knee arthroplasty were divided into group A (n = 300) and group B (n = 600). Patients in group A had home physiotherapy on their own after discharge from hospital. The physiotherapist did not visit them at home. Patients in group B received home physiotherapy under supervision of physiotherapist for 6 weeks after discharge from hospital. Patients’ age, range of motion of the knee, and forgotten joint score-12 were assessed. A p < 0.05 was considered statistically significant.

Results

In group A, the mean age was 69.1 ± 14.3 years (range: 58 to 82 years); in group B, the mean age was 66.5 ± 15.7 years (range: 56 to 83 years) (p > 0.05). Preoperatively, the mean range of motion of the knee in group A and B was 95.8° ± 18.1° and 95.4° ± 17.8°, respectively (p > 0.05). The mean forgotten joint score-12 of group A and B were 11.90 ± 11.3 and 11.72 ± 12.1 (p > 0.05), respectively. Six weeks after total knee arthroplasty, the mean ROM of the knee in group A and B was 109.7° ± 22.3° and 121° ± 21.5°, respectively (p < 0.05). The mean postoperative forgotten joint score-12 of the group A and B was 24.5 ± 16.4 and 25.6 ± 17.4, respectively (p > 0.05). The rate of manipulation under anaesthesia was 3% in group A and 0.2% in group B (p < 0.05).

Conclusion

After total knee arthroplasty, frequent physiotherapist’s instruction helps the patients improve knee exercises and therefore decrease the risk of revision surgery. The home physiotherapy under supervision of physiotherapist lowers the rate of manipulation under anaesthesia.

Level of evidence

Therapeutic study, Level IIa.

No clinical benefit of titanium nitride coating in cementless mobile-bearing total knee arthroplasty

PURPOSE

Titanium nitride (TiN) coating of cobalt-chromium-molybdenum (CoCrMo) implants has shown to improve the biomechanical properties of the implant surface and to reduce adhesive wear in vitro. It is yet unknown whether TiN coating of total knee prosthesis (TKP) affects the postoperative clinical outcome of total knee arthroplasty (TKA).

METHODS

In a double-blind randomized controlled clinical trial, 101 patients received an uncemented mobile-bearing CoCrMo TKP, either TiN coated or uncoated. Primary outcome measure visual analogue scale (VAS) score for pain, and secondary outcome measures Knee Society Score (KSS), revision rate and adverse events, range of motion of the knee as well as knee circumference and knee skin temperature were assessed 6 weeks, 6 months, 1 year and 5 years postoperative. Repeated measures analysis was used to evaluate the postoperative outcome measures over time.

RESULTS

There was no difference between the two groups in VAS score, KSS, revision rate, range of motion of the knee, knee circumference and knee skin temperature. There were no adverse events that could be related to the TiN coating.

CONCLUSIONS

TiN-coated TKP does not influence the postoperative outcome of uncemented mobile-bearing TKA regarding postoperative pain, revision rate, range of motion, swelling and temperature of the knee. Therefore, TiN coating of CoCrMo TKP has no clinical benefit on the outcome of cementless mobile-bearing TKA.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Do various factors affect the frequency of manipulation under anesthesia after primary total knee arthroplasty?

BACKGROUND

One of the most important goals of primary total knee arthroplasty (TKA) is to achieve a functional range of motion (ROM). However, up to 20% of patients fail to do so, which can impair activities of daily living.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate the effect of various (1) demographic factors; (2) comorbidities; and (3) knee-specific factors on the frequency of manipulation under anesthesia, which was used as an indicator of knee stiffness after a primary TKA.

METHODS

We evaluated the registries of two high-volume centers and reviewed all 3182 TKAs that were performed between 2005 and 2011 to identify all patients who had undergone manipulation under anesthesia (MUA). A total of 156 knees in 133 patients underwent MUA after an index arthroplasty. These patients were compared in a one-to-four ratio with a group of patients with satisfactory ROM drawn from the same database who met prespecified criteria and who had not undergone MUA. Effects of various factors, including age, sex, body mass index, race, comorbidities, and the underlying cause of knee arthritis, were compared between these two cohorts using multivariable logistic regressions.

RESULTS

After controlling for various confounding, nonwhite race was associated with an increase (odds ratio [OR], 2.01; p=0.03), and age≥65 years (OR, 0.17; 95% confidence interval [CI], 0.04-0.74; p=0.0179) was associated with a reduction in the incidence of MUA. In comorbidities, diabetes (OR, 1.72; 95% CI, 1.02-2.32; p=0.03), high cholesterol levels (OR, 2.70; p=0.03), and tobacco smoking (OR, 1.59; 95% CI, 1.03-2.47; p=0.03) were associated with an increase in frequency of MUA. In knee-specific factors, preoperative knee ROM of less than 100° (OR, 0.80; p<0.0001) and knee osteonecrosis (p=3.61; 95% CI, 1.29-10.1; p=0.014) were associated with increased frequency of MUA.

CONCLUSIONS

We identified several demographic, medical, and knee-specific factors that were associated with poor postoperative ROM in our patients undergoing TKA. Patients who have multiple risk factors may benefit from preoperative counseling to set realistic ROM expectations.

LEVEL OF EVIDENCE

Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Are revisions of patellofemoral arthroplasties more like primary or revision TKAs

BACKGROUND

Patellofemoral arthroplasty (PFA) can be considered in patients with patellofemoral disease. However, the use of partial arthroplasty often causes concern among clinicians and patients that revision to total knee arthroplasty (TKA) will be needed and, if so, whether this revision will be straightforward or more complicated.

QUESTIONS/PURPOSES

We set out to determine if conversion of a PFA to a TKA was more similar to a primary or to a revision TKA in terms of surgical characteristics, knee scores, range of motion, and complications.

METHODS

Between 2001 and 2008, we revised 21 PFAs to TKAs, all of which were available for followup at a minimum of 5 years (median, 6 years; range, 5-12 years). These patients were matched one-to-one by age, sex, body mass index, length of followup, and preoperative Knee Society Scores (KSS) to 21 primary and 21 revision TKAs. We analyzed operative time and amount of blood loss. Clinical outcomes assessed were range of motion and KSS.

RESULTS

Blood loss (405 mL versus 460 mL versus 900 mL; odds/hazard ratio, 1.33, 95% confidence interval [CI], 0.3-5.85; p=0.14 for primary TKA versus revision PFA and odds/hazard ratio, 0.13, 95% CI, 0.03-0.52; p<0.01 for revision PFA versus revision TKA) and operative time (52 minutes versus 72 minutes versus 115 minutes; odds/hazard ratio, 5.45, 95% CI, 1.23-27.4; p=0.02 for primary TKA versus revision PFA and odds/hazard ratio, 0.5, 95% CI, 0.01-0.44; p<0.001 for revision PFA versus revision TKA) were not different between the primary TKA and revision PFA groups but higher in the revision TKA group. KSS (knee and function) were higher in the primary TKA group (92 [range, 60-100] and 91 [range, 65-100]) than they were in the revision PFA (85 [range, 40-100] and 85 [range, 30-100]) and revision TKA groups (75 [range, 30-100] and 68 [range, 25-100]; p<0.001). Flexion was better in the primary TKA (125 [range, 105-130]) and revised PFA (120 [range, 100-130]) groups than the revision TKA group (105 [range, 80-115]; p=0.0013). There were more complications in the revision PFA group (two of 21) compared with the primary TKA group (zero of 21, p=0.005) but not compared with the revision TKA group (three of 21; p=0.85).

CONCLUSIONS

With the numbers available, we found that revising a PFA is comparable to a primary TKA in regard to surgical characteristics and postoperative clinical outcomes (including knee scores and range of motion), and both are superior to revision TKA, although the frequency of complications was higher in the revision PFA group than it was in the primary TKA group. The majority of patients undergoing revision of a PFA to a TKA can be treated with a standard implant.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The natural history of a newly developed flexion contracture following primary total knee arthroplasty

PURPOSE

We investigated the incidence, natural history, and functional consequences of a newly developed flexion contracture after total knee arthroplasty (TKA).

METHODS

Forty patients with full knee extension preoperatively who developed a postoperative flexion contracture were match-paired 1:2 with 80 patients who had full extension. The incidence of a newly developed flexion contracture, ROM, and Knee Society scores (KSS) at six weeks, four months, and one year were analysed.

RESULTS

The incidence of a new flexion contracture at six weeks was 14%, but diminished to 5% and 0.3% at four months and one year, respectively. One year after surgery, there was no difference in the KSS (p = 0.5).

CONCLUSIONS

This study showed that the majority of patients who developed a new flexion contracture after TKA have full knee extension one year postoperatively. Moreover, knee extension and KSS at one year are equivalent to those patients who did not developed a flexion contracture.

Mortality and perioperative complications after unicompartmental knee arthroplasty

AIM OF STUDY

Unicompartmental knee arthroplasty (UKA) has been increasingly utilized over the past decade secondary to favorable reports of better range of motion, higher activity levels, and increased patient satisfaction compared with total knee arthroplasty (TKA). The aim of this study was to determine the 90-day incidence of perioperative complications and mortality of patients undergoing UKA.

METHODS

One thousand consecutive UKA in 828 patients were retrospectively reviewed. A retrospective review was performed to evaluate 90-day perioperative complication and mortality rates.

RESULTS

There were zero deaths during the study period. Twelve percent of surgeries were complicated by variances within the 90-day postoperative period. There was one deep venous thrombosis (0.1%) and no pulmonary emboli. Cardiovascular complications were infrequent. Three patients had a myocardial infarction (0.31%), one developed congestive heart failure (0.1%), one angina (0.1%), and three had arrhythmias (0.31%). Secondary procedures were performed in 15 patients during the follow-up period: seven were manipulations under anesthesia for arthrofibrosis, one was an arthroscopic removal of retained cement, one arthroscopic removal of a drain, one repeat wound closure after a dehiscence secondary to a fall, one open reduction internal fixation for a supracondylar femur fracture, three irrigation and debridement procedures for an aseptic hematoma, and one radical debridement with later successful conversion to a total knee arthroplasty for a periprosthetic infection.

CONCLUSION

This study supports the notion that UKA is a safe procedure that is associated with a low rate of mortality and serious post-operative complications.

Fixed flexion deformity following total knee arthroplasty. A prospective study of the natural history

INTRODUCTION

Stiffness following total knee arthroplasty (TKA) is a disabling problem resulting in pain and reduced function.

OBJECTIVE

The aim of our study was to evaluate the natural course of fixed flexion deformity (FFD ) following primary total knee arthroplasty.

METHODS

Prospective review of 1626 patients undergoing primary TKA from 2001 to 2006 with a minimum of 4 year follow up. Demographic data included post-operative range of motion; type of prosthesis used, treatment modalities for stiffness and the final range of motion were recorded. FFD was defined as class 1(5-15 degrees) and Class 2 (> 15 degrees). Patients with a pre-operative FFD of >15, infection, stiffness treated with manipulation or revision surgery were excluded from the study.

RESULTS

Of the 1626 patients evaluated, 170 (10.5%) presented with a FFD. 18 patients were excluded from the study and 16 were lost to follow up. 124 (91.2%) were class 1 and 12 (8.8%) were class 2. FFD improved from a mean of 8.8 degrees to 0.4 degrees (p<0.0001) in 11.4 months. In 94.1% patients the FFD completely resolved (i.e. < 5 degrees) at a mean of 10.8 months (p<0.0001). In the remaining 5.9% of patients, FFD improved from a mean of 16.4 to 6.9 degrees at a mean follow up of 21.5 months (p<0.0001).

CONCLUSION

A gradual improvement in the FFD can be expected up to 2 years and a small residual flexion contracture does not cause functional deficit.

LEVEL OF EVIDENCE

Prospective cohort study, level 3.

Revision for stiffness following TKA: a predictable procedure?

BACKGROUND

Stiffness is a known complication following total knee arthroplasty. Multiple options are available to address this problem but revision TKA has been reported to be an effective treatment especially in the presence of technical issues such as oversized or loose components. However, it is not clearly known what factors may affect the outcome of revision TKA for stiffness. The purpose of this study was to evaluate the results of TKA revision for stiffness and to determine which potential factors may predict the outcome.

MATERIALS AND METHODS

Between 1999 and 2006, 39 patients (24 females and 15 males) were revised for stiffness following their primary TKA. The average age was 60.8 years with an average BMI of 30.7. The mean follow up was 74.4 months.

RESULTS

Following revision TKA, the overall range of motion and flexion contracture improved significantly from 68 to 90 (p=0.001) and from 14 to 5 (p<0.0001), respectively. Although the KSS were significantly improved from 45.72 to 77.10 (p<0.0001), the functional score did not improve significantly. Of the 39 knees which had stiffness, 10 (25.6%) required a second revision. We could not find any demographic or operative characteristics as a predictor failure.

CONCLUSION

Our study shows that TKA revision is a viable option, still unpredictable, to improve the ROM in patients with prolonged stiffness after TKA. Although revision for stiffness is not always successful in terms of achieving functional range of motion, it could improve pain in presence of less than functional range of motion.

LEVEL OF EVIDENCE

Prognostic Level II.

Pseudoaneurysm of the distal thigh after manipulation of a total knee arthroplasty

The authors describe a unique complication after manipulation of a stiff total knee arthroplasty in a 47-year-old man. Four days after undergoing manipulation under anesthesia (MUA), the patient presented with increasing pain and swelling of the affected knee and decreased hemoglobin/hematocrit. Computed tomographic angiogram revealed a ruptured pseudoaneurysm of a segmental branch of the deep femoral artery that was treated with embolization and anterior thigh compartment fasciotomy. Although many complications of MUA have been described, we present a novel finding of a ruptured pseudoaneurysm. Ruptured pseudoaneurysm should be included in the differential diagnosis whenever a patient presents with pain and swelling of the thigh after MUA given its potential morbidity.

BMP-2 Dependent Increase of Soft Tissue Density in Arthrofibrotic TKA

Arthrofibrosis after total knee arthroplasty (TKA) is difficult to treat, as its aetiology remains unclear. In a previous study, we established a connection between the BMP-2 concentration in the synovial fluid and arthrofibrosis after TKA. The hypothesis of the present study was, therefore, that the limited range of motion in arthrofibrosis is caused by BMP-2 induced heterotopic ossifications, the quantity of which is dependent on the BMP-2 concentration in the synovial fluid.

Eight patients with arthrofibrosis after TKA were included. The concentration of BMP-2 in the synovial fluid from each patient was determined by ELISA. Radiologically, digital radiographs were evaluated and the grey scale values were determined as a measure of the tissue density of defined areas. Apart from air, cutis, subcutis and muscle, the soft-tissue density in the area of the capsule of the suprapatellar pouch was determined. The connection between the BMP-2 concentration and the soft-tissue density was then investigated.

The average BMP-2 concentration in the synovial fluid was 24.3 ± 6.9 pg/ml. The density of the anterior knee capsule was on average 136 ± 35 grey scale values. A linear correlation was shown between the BMP-2 concentration in the synovial fluid and the radiological density of the anterior joint capsule (R=0.84, p = 0.009).

We were able to show that there is a connection between BMP-2 concentration and soft-tissue density in arthrofibrosis after TKA. This opens up the possibility of conducting a prophylaxis against arthrofibrosis in risk patients by influencing the BMP-2 pathway.

Internal rotation of the tibial component is frequent in stiff total knee arthroplasty

BACKGROUND

Stiffness complicating TKA is a complex and multifactorial problem. We suspected internally rotated components compromised motion because of pain, patellar maltracking, a tight medial flexion gap, and limited femoral rollback on a conforming lateral tibial condyle.

QUESTIONS/PURPOSES

We sought to determine: (1) the incidence of internal rotation of the femoral and tibial components in stiff TKAs; (2) if revision surgery that included correction of rotational positioning improved pain, ROM, and patellar tracking; and (3) if revision altered nonrotational radiographic parameters.

METHODS

From a cohort of 52 patients with TKAs revised for stiffness, we performed CT scans of 34 before and 18 after revision to quantify rotational positioning of the femoral and tibial components using a previously validated scanning protocol.

RESULTS

All 34 patients with TKAs had internal rotation of the summed values for tibial and femoral components (mean, 14.8°; range, 2.7°-33.7°) before revision for stiffness. The incidence of internal rotation was 24 of 34 femoral (mean, 3.1°; internal) and 33 of 34 tibial components (mean, 13.7° internal). Revision arthroplasty improved Knee Society function, knee, and pain scores. Mean extension improved from a contracture of 10.1° to 0.8° and flexion from 71.5° to 100°. Postrevision CT scans confirmed correction of component rotation. Nonrotational parameters were unchanged.

CONCLUSIONS

We recommend CT scanning of patients with stiff TKAs before surgical intervention to identify the presence of internally rotated components.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Arthroscopic arthrolysis for arthrofibrosis of the knee after total knee replacement

BACKGROUND

Arthrofibrosis is an uncommon but potentially debilitating complication following total knee replacement which can result in chronic pain and poor recovery of range of motion. The treatment of this condition remains difficult and controversial. QUESTIONS/AIMS OF STUDY: We reviewed our results of arthroscopic arthrolysis of arthrofibrosis of the knee after total knee replacement to assess the potential for this technique to improve range of motion and provide improvement in knee function and pain as measured by the Knee Society Score (KSS).

METHODS

Eight patients were treated for arthrofibrosis after total knee replacement with arthroscopic management. The patients included five females and three males. The average age was 67.4 years. Initial rehabilitation efforts, which included manipulation under anesthesia, had failed. Arthroscopic arthrolysis was performed to release fibrous bands in the suprapatellar pouch and to reestablish the medial and lateral gutters. Lateral release of the patellar retinaculum was performed. Intensive physiotherapy and continuous passive motion began immediately post-operatively. The average follow-up was 37.4 months. The KSS was used for assessment of pain and function before arthroscopy and at the latest follow-up.

RESULTS

Six of the eight patients experienced improvement in the KSS. The average functional score showed improvement from 68 points pre-operatively to 86 at the time of final follow-up. The average pain scores improved from 30 points pre-operatively to 41 at the time of final follow-up.

CONCLUSIONS

Arthroscopic management can be beneficial for patients suffering from arthrofibrosis following total knee replacement. Pain and KSS clinical scores can markedly improve.

Incidence and reasons for nonrevision reoperation after total knee arthroplasty

BACKGROUND

A dramatic increase in the demand for TKA is expected. The current burden of revision TKA is well known but the incidence and etiology of nonrevision reoperations after primary TKA is not.

QUESTIONS/PURPOSES

We determined the rate, reason, timing, and predictors of nonrevision reoperation after TKA.

METHODS

Using our institutional joint arthroplasty database, we identified 10,188 TKA performed on 7,613 patients between April 2000 and March 2008. A nonrevision reoperation was defined as any procedure requiring anesthetic in which components with bony interfaces were not removed or exchanged. Procedures after revision TKA were excluded. Potential risk factors investigated included age, gender, laterality, and simultaneous bilateral versus staged bilateral versus unilateral TKA. The minimum followup was 1 year (median, 4.1 years; range, 1.1 to 9.1 years).

RESULTS

Three hundred fifty-three patients of 7,613 (4.6%) underwent 434 nonrevision reoperations on 384 of 10,188 (3.8%) knees. The most common indication for nonrevision reoperation was stiffness (58%; 252 of 434), followed by patellar clunk (12%; 53), infection (12%; 52), wound revision (6%; 26), hematoma (4.4%; 19), among others. The median time to reoperation was 74.5 days (range, 1-3058 days) but varied widely. Younger patients and those with unilateral TKA were more likely to have a nonrevision reoperation.

CONCLUSIONS

The majority of nonrevision reoperations are performed for stiffness. Patellar clunk and infection also result in a large number of nonrevision reoperations. In weighing the future economic and workforce burden of TKA, nonrevision reoperations need to be acknowledged, and preventive measures need to be implemented.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Stiffness after revision total knee arthroplasty

Stiffness after a revision total knee arthroplasty (TKA) is a disabling complication that has largely been overlooked in the literature. This study attempts to define the prevalence of stiffness after revision TKA and to determine the risk factors that may lead to its development. Thirty-two knees (4.0%) presented with stiffness that we defined as a range of motion less than 90 degrees . Risk factors were found to be poor preoperative range of motion, stiffness as primary indication for revision, younger age, shorter interval between index primary and revision TKA, presence of well-fixed components at the time of revision, postoperative wound drainage, and lower Charlson index. Because of the challenges of treating stiffness, efforts should be invested in preventing this complication.

Mast cells and hypoxia drive tissue metaplasia and heterotopic ossification in idiopathic arthrofibrosis after total knee arthroplasty

BACKGROUND

Idiopathic arthrofibrosis occurs in 3-4% of patients who undergo total knee arthroplasty (TKA). However, little is known about the cellular or molecular changes involved in the onset or progression of this condition. To classify the histomorphologic changes and evaluate potential contributing factors, periarticular tissues from the knees of patients with arthrofibrosis were analyzed for fibroblast and mast cell proliferation, heterotopic ossification, cellular apoptosis, hypoxia and oxidative stress.

RESULTS

The arthrofibrotic tissue was composed of dense fibroblastic regions, with limited vascularity along the outer edges. Within the fibrotic regions, elevated numbers of chymase/fibroblast growth factor (FGF)-expressing mast cells were observed. In addition, this region contained fibrocartilage and associated heterotopic ossification, which quantitatively correlated with decreased range of motion (stiffness). Fibrotic, fibrocartilage and ossified regions contained few terminal dUTP nick end labeling (TUNEL)-positive or apoptotic cells, despite positive immunostaining for lactate dehydrogenase (LDH)5, a marker of hypoxia, and nitrotyrosine, a marker for protein nitrosylation. LDH5 and nitrotyrosine were found in the same tissue areas, indicating that hypoxic areas within the tissue were associated with increased production of reactive oxygen and nitrogen species.

CONCLUSIONS

Taken together, we suggest that hypoxia-associated oxidative stress initiates mast cell proliferation and FGF secretion, spurring fibroblast proliferation and tissue fibrosis. Fibroblasts within this hypoxic environment undergo metaplastic transformation to fibrocartilage, followed by heterotopic ossification, resulting in increased joint stiffness. Thus, hypoxia and associated oxidative stress are potential therapeutic targets for fibrosis and metaplastic progression of idiopathic arthrofibrosis after TKA.

Reactive oxygen and nitrogen species induce protein and DNA modifications driving arthrofibrosis following total knee arthroplasty

Background

Arthrofibrosis, occurring in 3%-4% of patients following total knee arthroplasty (TKA), is a challenging condition for which there is no defined cause. The hypothesis for this study was that disregulated production of reactive oxygen species (ROS) and nitrogen species (RNS) mediates matrix protein and DNA modifications, which result in excessive fibroblastic proliferation.

Results

We found increased numbers of macrophages and lymphocytes, along with elevated amounts of myeloperoxidase (MPO) in arthrofibrotic tissues when compared to control tissues. MPO expression, an enzyme that generates ROS/RNS, is usually limited to neutrophils and some macrophages, but was found by immunohistochemistry to be expressed in both macrophages and fibroblasts in arthrofibrotic tissue. As direct measurement of ROS/RNS is not feasible, products including DNA hydroxylation (8-OHdG), and protein nitrosylation (nitrotyrosine) were measured by immunohistochemistry. Quantification of the staining showed that 8-OHdg was significantly increased in arthrofibrotic tissue. There was also a direct correlation between the intensity of inflammation and ROS/RNS to the amount of heterotopic ossification (HO). In order to investigate the aberrant expression of MPO, a real-time oxidative stress polymerase chain reaction array was performed on fibroblasts isolated from arthrofibrotic and control tissues. The results of this array confirmed the upregulation of MPO expression in arthrofibrotic fibroblasts and highlighted the downregulated expression of the antioxidants, superoxide dismutase1 and microsomal glutathione S-transferase 3, as well as the significant increase in thioredoxin reductase, a known promoter of cell proliferation, and polynucleotide kinase 3'-phosphatase, a key enzyme in the base excision repair pathway for oxidative DNA damage.

Conclusion

Based on our current findings, we suggest that ROS/RNS initiate and sustain the arthrofibrotic response driving aggressive fibroblast proliferation and subsequent HO.

Stiffness in total knee arthroplasty

Stiffness is a relatively uncommon complication after total knee arthroplasty. It has been defined as a painful limitation in the range of movement (ROM). Its pathogenesis is still unclear even if some risk factors have been identified. Patient-related conditions may be difficult to treat. Preoperative ROM is the most important risk factor, but an association with diabetes, reflex sympathetic dystrophy, and general pathologies such as juvenile rheumatoid arthritis and ankylosing spondylitis has been demonstrated. Moreover, previous surgery may be an additional cause of an ROM limitation. Postoperative factors include infections, arthrofibrosis, heterotrophic ossifications, and incorrect rehabilitation protocol. Infections represent a challenging problem for the orthopaedic surgeon, and treatment may require long periods of antibiotics administration. However, it is widely accepted that an aggressive rehabilitation protocol is mandatory for a proper ROM recovery and to avoid the onset of arthrofibrosis and heterotrophic ossifications. Finally, surgery-related factors represent the most common cause of stiffness; they include errors in soft-tissue balancing, component malpositioning, and incorrect component sizing. Although closed manipulation, arthroscopic and open arthrolysis have been proposed, they may lead to unpredictable results and incomplete ROM recovery. Revision surgery must be proposed in the case of well-documented surgical errors. These operations are technically demanding and may be associated with high risk of complications; therefore they should be accurately planned and properly performed.