The posterior cruciate ligament in total knee arthroplasty

The purpose of this study was to answer 2 questions: Does the posterior cruciate ligament (PCL) produce femoral rollback in a single-design, cruciate-sparing total knee arthroplasty (TKA)? Does the PCL prevent posterior tibial displacement when it is retained after a single-design, cruciate-sparing TKA? Knee kinematics and limits of motion were measured with the knees in the following states: (1) intact knee, (2) anterior cruciate-deficient knee, (3) PCL-retaining total knee of a single design (TKA), (4) PCL-retaining TKA with PCL cut, and (5) PCL-substituting TKA. Femoral rollback was then calculated from the above data. The results showed that the PCL was able to prevent posterior translation and maintain femoral rollback when it was preserved during TKA. Therefore, the PCL can be functional after TKA, in a single-design, cruciate-sparing TKA. When the PCL was cut, significant changes in knee kinematics were observed.     

Posterior cruciate ligament removal contributes to abnormal knee motion during posterior stabilized total knee arthroplasty

Abnormal anterior translation of the femur on the tibia has been observed in mid flexion (20–60°) following posterior stabilized total knee arthroplasty. The underlying biomechanical causes of this abnormal motion remain unknown. The purpose of this study was to isolate the effects of posterior cruciate ligament removal on knee motion after total knee arthroplasty. We posed two questions: Does removing the posterior cruciate ligament introduce abnormal anterior femoral translation? Does implanting a posterior stabilized prosthesis change the kinematics from the cruciate deficient case? Using a navigation system, we measured passive knee kinematics of ten male osteoarthritic patients during surgery after initial exposure, after removing the anterior cruciate ligament, after removing the posterior cruciate ligament, and after implanting the prosthesis. Passively flexing and extending the knee, we calculated anterior femoral translation and the flexion angle at which femoral rollback began. Removing the posterior cruciate ligament doubled anterior translation (from 5.1 ± 4.3 mm to 10.4 ± 5.1 mm) and increased the flexion angle at which femoral rollback began (from 31.2 ± 9.6° to 49.3 ± 7.3°). Implanting the prosthesis increased the amount of anterior translation (to 16.1 ± 4.4 mm), and did not change the flexion angle at which femoral rollback began. Abnormal anterior translation was observed in low and mid flexion (0–60°) after removing the posterior cruciate ligament, and normal motion was not restored by the posterior stabilized prosthesis. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1494–1499, 2008     

Knee stability in posterior cruciate ligament retaining total knee arthroplasty

Anteroposterior knee laxity was evaluated in 14 patients (19 knees) who had posterior cruciate ligament retaining total knee arthroplasty using the Miller Galante I prosthesis. The followup ranged from 87 to 118 months (average, 105.9 months), and the measurements were done using the KT-2000 arthrometer. The mean anteroposterior displacement with the knees with Miller Galante I prostheses was 10.1 mm at 30 degrees flexion and 8.1 mm at 75 degrees flexion. In the 15 knees with Miller Galante I prostheses with flexion greater than 90 degrees, seven had less stability at 75 degrees than at 30 degrees flexion. These knees were considered to have a nonfunctional posterior cruciate ligament, and they had a worse Knee Society score (81.1) than did the other eight knees with Miller Galante I prostheses (89.9). There were four knees in which the flexion was less than 90 degrees. In this study, approximately half of the knees with posterior cruciate ligament retaining total knee arthroplasty did not have good anteroposterior stability in flexion an average of 9 years after surgery.     

Functional comparison of posterior cruciate-retaining versus posterior stabilized total knee arthroplasty

A prospective, randomized comparison of posterior cruciate-retaining (PCR) and posterior stabilized (PS) total knee arthroplasties (TKAs) was conducted in 20 patients who underwent bilateral TKAs for osteoarthritis. All procedures were performed by a single surgeon. One knee was implanted with a PCR TKA, and a contralateral knee with a PS TKA. Both prosthetic designs were of the same TKA series, with comparable surface geometries. Patients had a clinical and radiographic evaluation at a mean of 31.7 months for PCR TKAs and 30.6 months for PS TKAs postoperatively. There were no significant differences between the PCR and PS TKAs in postoperative knee scores. However, postoperative improvement in range of motion was significantly superior in the PS group.     

Evaluation of the posterior cruciate ligament in long standing cruciate retaining total knee arthroplasty

We evaluated the status of the posterior cruciate ligament in 52 knees with a cruciate retaining total knee arthroplasty 11 years after the index surgery. The evaluation consisted of the Knee Society scores, clinical examination of antero-posterior laxity using the Lachmann test and posterior drawer test. We also used the KT 1000 device, stress radiographs and MRI scan to corroborate this. Three knees were found to be lax clinically and had a posterior tibial shift on radiographs. The MRI scans were able to delineate the posterior cruciate ligament in 86% of the knees. Eleven years after surgery, clinical, radiological and MRI scans when assessed in combination demonstrated the presence of a stable posterior cruciate ligament in 94%.     

Quadriceps-sparing total knee arthroplasty using the posterior stabilized TKA design

Minimally invasive TKA is in the early stages of development. Healthy skepticism is appropriate until long-term data has been reported. Early results with the quadriceps-sparing technique are encouraging. It appears to be less painful and entail a shorter recovery time. We hope the results will remain stable as the follow-up time increases.     

An algorithm for the posterior cruciate ligament in total knee arthroplasty.

The fate of the posterior cruciate ligament in primary total knee arthroplasty is controversial. An algorithmic approach is presented that is based on pathologic criteria for evaluating and treating patients with primary total knee arthroplasty that will aid in the posterior cruciate ligament decision-making process, producing more predictable procedures and outcomes. A consecutive series of the first 120 patients (171 knees) who had primary posterior cruciate-retaining arthroplasty and the first 120 patients (180 knees) who had primary posterior-stabilized arthroplasty with a minimum 5-year followup in which the Maxim Complete Total Knee System and the algorithmic approach were used were compared. No statistically significant differences in outcome between the groups were observed. Among the patients who had posterior cruciate-retaining arthroplasty, no revisions attributable to aseptic loosening have been reported at an average followup of 6.39 years. The average followup Knee Society total score was 162.16 points, with 91 (54.8%) knees having excellent outcome ratings. No revisions attributable to aseptic loosening have been reported among the patients who had posterior-stabilized arthroplasty at an average followup of 5.98 years. The average followup Knee Society total score was 158.05 points, with excellent outcome ratings reported in 96 (54.9%) knees. The use of a standardized algorithm has streamlined the treatment of patients having primary total knee arthroplasty, consistently providing excellent clinical results when either retaining or sacrificing the posterior cruciate ligament.     

Effect of the posterior cruciate ligament in knee-joint proprioception in total knee arthroplasty

The primary purpose of the study was to examine the role of the posterior cruciate ligament (PCL) in knee-joint proprioception after total knee arthroplasty (TKA). Knee-joint proprioception was measured in 10 patients with nonsacrificed PCL TKAs and 10 with sacrificed PCL TKAs. Knee-joint proprioception was evaluated through reproduction of static knee angles using a Penny and Giles™ electrogoniometer. The primary variable was absolute angular error (AAE). AAE was defined as the absolute value of the difference between the test angle and the patient's perceived version of the test angle. Proprioception deficit was compared to the WOMAC questionnaire which evaluates pain, stiffness, and physical function of the lower extremity. No significant difference was found between the nonsacrificed PCL TKA (4.33° ± 1.52°) and sacrificed PCL TKA (4.38° ± 1.39°) AAE values (P > .4). Furthermore, no significant differences were observed in the WOMAC questionnaire scores for all three parameters between the two types of knee prosthesis (P > .35). The current findings suggest that the preservation of the PCL in TKA may not improve knee-joint proprioception and subsequently may not improve TKA functional performance.     

Navigation-assisted less invasive total knee arthroplasty compared with conventional total knee arthroplasty: a randomized prospective trial

The purpose of this study was to evaluate the hypothesis that a less invasive (LIS) surgical technique using a navigation system would promote rapid recovery and improve alignment compared with conventional technique in total knee arthroplasty (TKA). This study compared 49 navigation-assisted LIS TKAs with 53 conventionally performed TKAs using a medial parapatellar arthrotomy with patellar eversion. Navigation-assisted LIS TKA used a shorter skin incision, a midvastus approach without patella eversion, and a navigation system. Navigation-assisted LIS TKA had better pain scores, shorter times to achieve 90 degrees flexion and straight leg raise, and a smaller extension lag during the very early postoperative period. However, there were no differences between the groups 2 weeks postoperatively. There were no differences in mean prosthetic alignment between the 2 groups, but the navigation-assisted LIS group had fewer "outliers" than the conventionally performed TKA group.     

Proprioception following total knee arthroplasty with and without the posterior cruciate ligament

Proprioception was measured in two groups of patients following successful total knee arthroplasty (TKA). In one group, the posterior cruciate ligament was retained and an unconstrained cruciate-retaining total knee component was used; in the other group, the posterior cruciate ligament was excised and a cruciate-substituting design was implanted. Threshold to detection of passive motion was quantified as a measure of proprioception. The degree of preoperative arthritis was objectively classified according to Resnick and Niwoyama. There was no difference in threshold to detection of passive motion in cruciate-retaining versus cruciate-substituting TKA. In patients with a moderate grade of arthritis before surgery, the postoperative scores were virtually identical. When the grade of preoperative arthritis was severe, patients with cruciate-substituting TKAs performed significantly better than those with cruciate-retaining TKAs.     

Patellar resurfacing in total knee arthroplasty: a prospective, randomized trial

BACKGROUND: The management of the patella in total knee arthroplasty is still problematic. We aimed to identify differences in the clinical outcome of total knee arthroplasty according to whether or not patellar resurfacing had been performed in a prospective, randomized study of 220 osteoarthritic knees. METHODS: Two hundred and twenty total knee arthroplasties in 201 patients were randomly assigned to be performed with either resurfacing or retention of the patella, and the results were followed for a mean of forty-eight months (range, thirty-six to seventy-nine months) in a double-blind (both patient and clinical evaluator blinded), prospective study. Evaluation was performed annually by an independent observer and consisted of assessment with the Knee Society clinical rating system, specific evaluation of anterior knee pain, a stair-climbing test, and radiographic examination. RESULTS: Fifteen (12%) of the 128 knees without patellar resurfacing and nine (10%) of the ninety-two knees with patellar resurfacing underwent a revision or another type of reoperation related to the patellofemoral articulation. This difference was not significant (chi square with one degree of freedom = 0.206, p = 0.650). At the time of the latest follow-up, there was a significantly higher incidence of anterior pain (chi square with one degree of freedom = 5.757, p = 0.016) in the knees that had not had patellar resurfacing. CONCLUSIONS: Patients who underwent patellar resurfacing had superior clinical results in terms of anterior knee pain and stair descent. However, anterior knee pain still occurred in patients with patellar resurfacing, and nine (10%) of the ninety-two patients in that group underwent a revision or another type of reoperation involving the patellofemoral joint. Weight but not body mass index was associated with the development of anterior knee pain in the patients without patellar resurfacing, a finding that suggests that patellofemoral dysfunction may be a function of joint loading rather than obesity.     

Retention versus removal of the posterior cruciate ligament in total knee replacement: a systematic literature review within the Cochrane framework

Background There is no consensus as to whether to use a posterior cruciate ligament (PCL) retaining design or a posterior-stabilized design for total knee arthroplasty. The objective of this study was to establish the difference in functional, clinical, and radiological outcome between retention and removal of the PCL.

Methods We conducted a search in Medline, EMBASE, the Cochrane database, and Current Contents, along with reference checks and citation tracking. Randomized controlled trials were selected and methodological quality was assessed with the van Tulder and Jadad checklists by 2 independent reviewers.

Results We found 8 randomized controlled trials. 2 treatment options were compared against PCL retention: PCL removal without post and cam mechanism (2 studies), and posterior-stabilized design (5 studies). 1 study included all 3 options. Range of motion was found to be 8° higher (105° vs. 113°) in the posterior-stabilized group compared to the PCL retention group (p = 0.01, 95% CI (1.7, 15)).

Interpretation These results should be interpreted with caution, as the methodological quality of the studies was highly variable. Suggestions are given to improve future research on this specific aspect of knee arthroplasty.

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In vivo function of posterior cruciate ligament before and after posterior cruciate ligament-retaining total knee arthroplasty

Purpose

The object of this study was to investigate the in vivo function of the posterior cruciate ligament (PCL) in patients before and after a PCL-retaining total knee arthroplasty (TKA).

Methods

Eleven patients with advanced osteoarthritis (OA) of the knee were recruited. Magnetic resonance scans of each OA knee were obtained, and 3D computer models, including the femoral and tibial insertion areas of the anterolateral and posteromedial bundles of the PCL, were created. Before and after PCL-retaining TKA, dual fluoroscopic images of each knee were acquired during weight-bearing knee flexion. The images and computer models were used to reproduce the in vivo motion of the knee. The function of the PCL bundles was described in terms of elongation, elevation and deviation. Twenty-two healthy controls were also included as normal references.

Results

PCL bundles of the OA knees were overstretched during late knee flexion and orientated more medially throughout flexion compared with normal knees. After PCL-retaining TKA, PCL bundles were further overstretched during late flexion and changed from medially directed in normal and OA knees to almost sagittally directed, which may compromise function in controlling knee rotation.

Conclusions

The current PCL-retaining TKA systems and surgical techniques may not adequately re-establish normal biomechanics of PCL bundles after PCL-retaining TKA.     

Minimally invasive total hip arthroplasty: a randomized controlled prospective trial

Introduction

Advantages of minimally invasive total hip arthroplasty (THA) are controversially discussed.

Method

In this prospective study 51 patients (52 hips) were randomly allocated to a classical lateral or a minimally invasive approach (modification of the Hardinge-approach). Operating time, intraoperative blood loss, postoperative hemoglobin, muscle enzymes CK and myoglobin were recorded. Radiologically the positioning of the prosthesis was analyzed. WOMAC- and Harris Hip Score (HHS) were assessed preoperatively, at discharge, at 6 weeks and 3 months.

Results

In the minimally invasive group there was a shorter length of surgery, the scores in the WOMAC and HHS were slightly better at discharge and at the 3 months- examination, myoglobin-rise was slightly less. The positioning of the prosthesis was good in both groups. Minimally invasive THA led to a quicker recovery, at 3 months postoperative there was still a slight difference to the standard group.

Conclusion

If these slight differences subside has to be examined in studies with a longer follow-up.     

Decreased posterior tibial slope increases strain in the posterior cruciate ligament following total knee arthroplasty

The purpose of this study was to measure the strain in the posterior cruciate ligament as a function of knee flexion angle and posterior tibial slope following total knee arthroplasty with a posterior cruciate ligament-retaining design. Posterior cruciate ligament strain was measured in seven fresh-frozen cadavers for posterior tibial slopes of 10°, 8°, and 5°. For all three levels of tibial slope tested, strain in the posterior cruciate ligament increased with increasing flexion angle to approximately 100° and then decreased with increasing flexion. The strain measured at 8° posterior tibial slope was greater than that measured at 10°, but the difference was not significant. The strain measured at 5° posterior slope was significantly greater than strain measured at both 8° and 10°. This increased strain may result in altered knee kinematics and reduced range of motion at higher flexion angles.     

Is the effect of a posterior cruciate ligament resection in total knee arthroplasty predictable?

Purpose  

It is broadly supposed that in total knee arthroplasty, the flexion/extension gap ratio is increased after resection of the posterior cruciate ligament (PCL). However, studies are rare and results are inconsistent. Therefore, this study was conducted to determine whether PCL release regularly increases the flexion gap.     

In vitro investigation of posterior cruciate ligament strain following total knee arthroplasty

AIM: The aim of this biomechanical in vitro study was to assess posterior cruciate ligament (PCL) strain following two different total knee arthroplasty (TKA) designs (fixed versus mobile) with regard to modification of the tibial slope. MATERIAL AND METHODS: We investigated eight Natural Knee I (NK I) prosthesis with fixed bearing and eight Low Contact Stress (LCS) prosthesis with mobile meniscal bearings. TKA was performed using fresh frozen human cadaveric knee joints. PCL strain was measured with implantable force transducers. Knee kinematic assessment was made with a load of 300 Newton and without load using a six-degrees-of-freedom testing device. Modification of the tibial slope was analysed radiographically. Statistical analysis was performed using Student's t test, Wilcoxon rank sum test, and the Spearman coefficient of correlation. RESULTS: Assessment of the tibial slope showed a non-significant increase of 2.1 degrees (p = 0.14) following TKA using the NK I, and of 1.1 degrees (p = 0.12) using the LCS, respectively. Analysis of PCL strain following implantation of the NK I prosthesis revealed non-significant alterations both with (p = 0.74) and without load (p = 0.20). Concerning the LCS prosthesis, a significant decrease in PCL strain was seen with load (p = 0.01), whereas non-significant modifications were measured without load (p = 1.0). The modified tibial slope and modified PCL strain following LCS TKA showed no (with load: r (s) = 0.01) and modest correlation (without load: r (s) = - 0.43), respectively, whereas it was substantial following NK I TKA (with load: r (s) = 0.64, without load: r (s) = 0.70). CONCLUSION: As the NK I prosthesis allows PCL tension to be close to normal as the knee flexes, it can be stated that regular PCL tension after TKA is restorable and, moreover, it can be hypothesised that the effected tension of the PCL mainly depends on the interaction between design of the implant (fixed/mobile) and the functional role of the PCL.     

Tight posterior cruciate ligament in posterior cruciate-retaining total knee arthroplasty: a cause of posteromedial subluxation of the femur

Posteromedial subluxation has been reported as a mode of failure with flat-on-flat articular geometry. Medical records were reviewed to find patients who developed progressive subluxation of the femur. From a consecutive series of 2,773 primary anatomically graduated components (AGC) knees, 6 patients developed progressive posterior subluxation of the femur. The mean interval between the index total knee arthroplasty (TKA) and the diagnosis of subluxation was 4.8 years. Five cases were revised at an average of 6.2 years after index TKA. Tightness of the posterior cruciate ligament (PCL) was observed in all revised cases. Progressive posterior subluxation is a rare complication after AGC knees. It is believed that the primary factor causing progressive subluxation is tightness of the PCL. The PCL should be recessed if PCL tightness is seen at surgery.