Postoperative Anteroposterior Laxity Influences Subjective Outcome After Total Knee Arthroplasty

Effect of posterior capsular release on intraoperative joint gap mismatch in the mid-flexion range during posterior-stabilized total knee arthroplasty

INTRODUCTION

Intraoperative mismatch between extension and mid-flexion joint gaps remains a critical issue in posterior-stabilized total knee arthroplasty (PS-TKA). Posterior capsular release has been found to increase the extension joint gap. However, there is still a lack of robust evidence for the effect of posterior capsular release on the mid-flexion joint gap. The purpose of the present study was to quantify the effect of posterior capsular release on the intraoperative joint gap from extension through 45° mid-flexion to flexion and to clarify how this procedure might affect the improvement of gap mismatch in the mid-flexion 45° range.

MATERIALS AND METHODS

In total, 38 consecutive cases of primary PS-TKA were reviewed. The center, medial, and lateral component gaps from extension to flexion were measured with a tensor device before and after posterior capsular release. The minimal detectable change for joint gap measurement was calculated using two methods, error variance and intra-observer intraclass correlation coefficients. Pre- and post-release joint gap differences were assessed using the paired t-test.

RESULTS

Minimal detectable change was found to be 0.59 mm. At 0° and 10° of flexion, the post-release center, medial, and lateral component gaps were significantly greater than at pre-release. At 45° and 90° and maximum flexion, there were no joint gap differences exceeding the minimal detectable change. The joint gap mismatches between 0° and 10°, and 45°, 90° and maximum flexion were significantly smaller at post-release than those at pre-release with the change values exceeding the minimal detectable change (P < 0.05).

CONCLUSION

Posterior capsular release significantly decreased both joint gap mismatch between extension and 45° mid-flexion, and extension and flexion, showing clinical usefulness in PS-TKA.

The Correlation between Objective Ligament Laxity and the Clinical Outcome of Mechanically Aligned TKA

Instability is one of the causes of failure in total knee arthroplasty (TKA). The aim of this study was to analyze the correlation between objective ligament laxity and the clinical outcome of mechanically aligned TKA. Fifty-one knees in 47 patients were evaluated at a minimum follow-up of 6 months. The correlation between the angular displacement and functional scores (Knee Society Score and Knee Injury and Osteoarthritis Score) was analyzed. A negative correlation (p-value < 0.05) was observed between medial laxity ≥5° at 0, 30, 60, and 90° of flexion and the outcome measures. Lateral laxity did not correlate with the clinical outcome. At 30° of knee flexion, a total varus and valgus laxity ≥10° was related to poorer outcomes. The same amount of angular displacement did not influence the outcome in the other flexion angles. There was no difference in single-radius vs multi-radius implants in terms of medial and lateral laxity and clinical outcome. A valgus displacement ≥5° measured at 0, 30, 60, and 90 degrees of flexion correlated with an inferior clinical outcome. In contrast, the same amount of displacement measured on the lateral compartment did not influence the clinical outcome after TKA.

Catastrophic Mid-Flexion Instability After Avulsion Fractures of the Articular Capsule of the Femur and Tibia in a Patient With Posterior-Stabilized Total Knee Arthroplasty: A Case Report

Mid-flexion instability can be caused by patient-related, implant-related, or technique-specific factors and impairs the activities of daily living after total knee arthroplasty (TKA). In this study, we report a rare case of a patient with severe mid-flexion instability following tibial and femoral avulsion fractures after posterior-stabilized (PS) TKA for knee osteoarthritis. An 82-year-old female with bilateral knee osteoarthritis underwent staged bilateral TKA with a posterior-stabilized prosthesis. The course of the early postoperative period was good, and the patient was able to walk independently with a cane. Two months postoperatively, the patient fell and then experienced left knee pain and instability in the mid-flexion range. Radiographic images showed avulsion fractures of the articular capsule of the femur and tibia, and fluoroscopic examination showed severe posterior subluxation of the tibia between 40° and 60° of flexion. Conservative treatment with a functional knee brace and quadriceps training was initiated due to the patient's hesitation to undergo a second surgery; however, no improvement was observed. Eventually, revision surgery was planned three months after the fall incident (five months after the left primary TKA). At revision surgery, osteosynthesis of the tibial avulsion fracture and thickening of the PS insert did not sufficiently stabilize the instability, and revision TKA with a rotating-hinge prosthesis was needed. The postoperative course was uneventful, and she was able to walk with a cane within two weeks after revision TKA with no complaints of instability. Two years postoperatively, the patient recovered well and had no recurrence of instability, pain, or dysfunction. This case report shows that loss of support by the joint capsules due to avulsion fractures may cause significant anteroposterior instability in the mid-flexion position after posterior-stabilized TKA. In such a case, conservative treatment failed, and the revision of the rotating-hinge prosthesis provided stability and good improvement.

Medial Soft Tissue-Preserving Technique Impact on Sagittal Stability in Bi-cruciate Stabilized Total Knee Arthroplasty

Background

Sagittal stability in total knee arthroplasty is achieved through complex processes enabled by prosthetic design and intraoperative soft tissue balancing. This study investigated the effects of preserving medial soft tissue on sagittal stability in bicruciate stabilized total knee arthroplasty (BCS TKA).

Method

This retrospective study included 110 patients who underwent primary BCS TKA. The patients were divided into two groups: 44 TKAs were performed releasing medial soft tissue (CON group), and 66 TKAs were performed preserving medial soft tissue (MP group). We assessed joint laxity using tensor device and anteroposterior translation immediately after surgery using the arthrometer at 30° knee flexion. Propensity score matching (PSM) was performed according to preoperative demographic and intraoperative medial joint laxity, and further comparisons between the two groups were performed.

Result

After PSM analysis, medial joint laxity in the mid-flexion range tended to be smaller in the MP group than in the CONT group, with a significant difference at 60 degrees (CON group: - 0.2 ± 0.9 mm, MP group: 0.8 ± 1.3 mm, P < 0.05). Anteroposterior translation was significantly different between the two cohorts (CON group: 11.6 ± 2.5 mm, MP group: 8.0 ± 3.1 mm, P < 0.001).

Conclusion

This study demonstrated the effects of preserving medial soft tissue on postoperative sagittal stability in BCS TKA. We concluded that this surgical procedure enhances postoperative sagittal stability in the mid-flexion range in BCS TKA.

Mid-Flexion, Anteroposterior Stability of Total Knee Replacement Implanted with Kinematic Alignment: A Randomized, Quantitative Radiographic Laxity Study with Posterior-Stabilized and Medial-Stabilized Implants

UPDATE

This article was updated on January 4, 2023, because of a previous error, which was discovered after the preliminary version of the article was posted online. On page 16, in Figure 5, the x-axis that had read "P<0.0086" now reads "KSS Pain (p=0.02)," and the value for the MS group that had read "48.9" now reads "48.8."This article was updated on January 6, 2022, because of a previous error. On page 13, in the section entitled "Results," the sentence that had read "However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the MS group (2.3 versus 5.4 mm; p = 0.008)." now reads "However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the PS group (2.3 versus 5.4 mm; p = 0.008)."

BACKGROUND

Stability in mid-flexion is important for satisfactory clinical outcomes following total knee arthroplasty (TKA). The purpose of the present study was to compare the anteroposterior stability of knees that had been treated with a posterior-stabilized (PS) device or a medial-stabilized (MS) device. We hypothesized that mid-flexion laxity would be greater in the PS group and that clinical outcome scores would be better for the group with lower laxity.

METHODS

Sixty-three patients who had been randomly selected from a larger randomized, prospective, blinded clinical trial underwent primary TKA with either a PS implant (n = 30) or an MS implant (n = 33). Range of motion, the Knee Society Score (KSS), and the Forgotten Joint Score (FJS) were collected, and anteroposterior laxity with the knee in 45° and 90° of flexion was evaluated with stress radiographs.

RESULTS

In 45° of flexion, the MS group demonstrated significantly less total anteroposterior displacement than the PS group (mean, 3.6 versus 16.5 mm; p ≤ 0.0001). In 90° of flexion, the total anteroposterior displacement was not significantly different for the 2 groups when both male and female patients were included (mean, 3.9 versus 5.9; p = 0.07). However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the PS group (2.3 versus 5.4 mm; p = 0.008). The groups did not differ significantly in terms of preoperative age, body mass index, sex distribution, FJS, KSS, or range of motion, and they also did not differ in terms of postoperative FJS or range of motion. However, all 33 patients in the MS group returned to sports as indicated in question 12 of the FJS, compared with 19 subjects in the PS group (p = 0.0001). The postoperative KSS Pain, Pain/Motion, and Function scores were all significantly higher in the MS group than the PS; specifically, the mean KSS Pain score was 48.8 in the MS group, compared with 44.8 in the PS group (p = 0.02); the mean KSS Pain/Motion score was 98.4 in the MS group, compared with 89.5 in the PS group (p < 0.0001); and the mean KSS Function score was 95.5 in the MS group, compared with 85.7 in the PS group (p = 0.003).

CONCLUSIONS

Mid-flexion laxity was greater in patients with PS implants than in those with MS implants, and laxity in 90° was greater in the subset of female patients in the PS group. The decreased laxity observed in the MS group correlated with higher KSS Pain, Pain/Motion, and Function scores as well as with a higher rate of return to sports activities.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Medial pivot-based total knee arthroplasty achieves better clinical outcomes than posterior-stabilised total knee arthroplasty

PURPOSE

Stability in the sagittal plane, particularly regarding anterior cruciate ligament compensation, and postoperative functionality and satisfaction remain issues in total knee arthroplasty. Therefore, this prospective study compared the clinical outcomes between medial-pivot-based and posterior-stabilised total knee arthroplasty based on anterior translation and clinical scores.

METHODS

To assess outcomes of total knee arthroplasty for varus osteoarthritis, the anterior translation distance of the tibia relative to the femur was measured at 30 and 60° of flexion using a KS measure Arthrometer at 6 months postoperatively. The 2011 Knee Society Score, Forgotten Joint Score, visual analogue scale for pain, and range of motion were assessed at 6 months and 1 year postoperatively. The correlations among each score, anterior translation distance, range of motion, and visual analogue scale score for pain were investigated.

RESULTS

The medial-pivot and posterior-stabilised groups comprised 70 and 51 patients, respectively. The medial-pivot group exhibited a significantly shorter anterior translation distance at 60° flexion than the posterior-stabilised group. Furthermore, the medial-pivot group achieved significantly better outcomes regarding the visual analogue scale for pain, 2011 Knee Society Score, and Forgotten Joint Score than the posterior-stabilised group. A significant negative correlation was observed between the anterior translation distance and the function score of the 2011 Knee Society Score, whereas a significant positive correlation was found between the anterior translation distance and flexion angle, and between the extension angle and score of the Forgotten Joint Score or 2011 Knee Society Score. Significant negative correlations were also found between the pain visual analogue scale and both the 2011 Knee Society Score and Forgotten Joint Score.

CONCLUSION

In total knee arthroplasty for osteoarthritis, the medial-pivot group displayed a shorter anterior translation distance than the posterior-stabilised group at 6 months postoperatively. The visual analogue scale score for pain was also significantly lower in the medial-pivot group than that in the posterior-stabilised group at both 6 months and 1 year postoperatively. Because a correlation was observed between the anterior translation distance and the function score, medial-pivot-based total knee arthroplasty was considered to significantly improve postoperative function compared to posterior-stabilised total knee arthroplasty.

Outcomes are Better With a Medial-Stabilized vs a Posterior-Stabilized Total Knee Implanted With Kinematic Alignment

BACKGROUND

There is no consensus whether a posterior-stabilized (PS) total knee device is superior to a more congruent, cruciate-substituting, medial-stabilized device (MS). This study compared the clinical outcomes of these devices. The primary hypothesis was that the clinical outcomes would be better in the MS group implanted with kinematic alignment.

METHODS

This prospective, randomized, single-center Level 1 study compared the outcomes of 99 patients who received a PS device and 101 patients who received an MS device implanted with kinematic alignment. Institutional Review Board approval and informed consent were obtained. Clinical and radiographic assessments were performed preoperatively, 6 weeks, 6 months, and annually.

RESULTS

All subjects reached the minimum follow-up of 2 years. There were no statistically significant differences in demographic characteristics, preoperative scores, or alignment (preoperative or postoperative). Tourniquet time was 7.24% longer for the PS group (40.28 min vs 37.56 min, P < .0086). There were significant differences between groups for the 1-year and 2-year Knee Society scores, Forgotten Joint Score, and ROM; in every case favoring the MS group. The FJS was 68.3 in the MS group at 2 years and 58.3 in the PS group (P = .02). The maximum flexion at 2 years was 132° in the MS group and 124° in the PS group (P < .0001).

CONCLUSION

The clinical outcomes of the MS group at 1 and 2 years were better. At the minimum 2-year follow-up, the results demonstrate the superiority of the medial-stabilized device in terms of multiple clinical outcomes.

LEVEL OF EVIDENCE

I.

Inter-Rater Reliability of Clinical Testing for Laxity After Knee Arthroplasty

BACKGROUND

The clinical examination for laxity has been considered a mainstay in evaluation of the painful knee arthroplasty, especially for the diagnosis of instability. More than 10 mm of anterior-posterior (AP) translation in flexion has been described as important in the diagnosis of flexion instability. The inter-observer reliability of varus/valgus and AP laxity testing has not been tested.

METHODS

Ten subjects with prior to total knee arthroplasty (TKA) were examined by 4 fellowship-trained orthopedic knee arthroplasty surgeons. Each surgeon evaluated each subject in random order and was blinded to the results of the other surgeons. Each surgeon performed an anterior drawer test at 30 and 90 degrees of flexion and graded the instability as 0-5 mm, 5-10 mm or >10 mm. Varus-valgus testing was also graded. Motion capture was used during the examination to determine the joint position and estimate joint reaction force during the examination.

RESULTS

Inter-rater reliability (IRR) was poor at 30 and 90 degrees for both the subjective rater score and the measured AP laxity in flexion (k = 018-0.22). Varus-valgus testing similarly had poor reliability. Force applied by the rater also had poor IRR.

CONCLUSION

Clinical testing of knee laxity after TKA has poor reliability between surgeons using motion analysis. It is unclear if this is from differences in examiner technique or from differences in pain or quadriceps function of the subjects. Instability after TKA should not be diagnosed strictly by clinical testing and should involve a complete clinical assessment of the patient.

Limited effect of anatomical insert geometry on in vitro laxity in balanced anatomic posterior cruciate ligament retaining total knee arthroplasty

PURPOSE

The present study assessed the effect of insert articular surface geometry (anatomical versus conventional insert design) on anteroposterior (AP) translation and varus-valgus (VV) laxity in balanced posterior cruciate ligament (PCL) retaining total knee arthroplasty (TKA). Secondly, we evaluated if the AP translation and VV laxity in the reconstructed knee resembled the stability of the native knee.

METHODS

Nine fresh-frozen full-leg cadaver specimens were used in this study. After testing the native knee, anatomical components of a PCL-retaining implant were implanted. The knee joints were subjected to anteriorly and posteriorly directed forces (at 20° and 90° flexion) and varus-valgus stresses (at 20°, 45° and 90° flexion) in both non-weightbearing and weightbearing situations in a knee kinematics simulator. Measurements were performed in the native knee, TKA with anatomical insert geometry (3° built-in varus, medial concave, lateral convex), and TKA with symmetrical insert geometry.

RESULTS

In weightbearing conditions, anterior translations ranged between 2.6 and 3.9 mm at 20° flexion and were < 1 mm at 90° flexion. Posterior translation at 20° flexion was 2.7 mm for the native knee versus 4.0 mm (p = 0.047) and 7.0 mm (p = 0.02) for the symmetrical insert and the anatomical insert, respectively. Posterior translation at 90° flexion was < 1.1 mm and not significantly different between the native knee and insert types. In non-weightbearing conditions, the anterior translation at 20° flexion was 5.9 mm for the symmetrical and 4.6 mm for the anatomical insert (n.s.), compared with 3.0 mm for the native knee (p = 0.02). The anterior translation at 90° flexion was significantly higher for the reconstructed knees (anatomical insert 7.0 mm; symmetrical insert 9.2 mm), compared with 1.6 mm for the native knee (both p = 0.02). Varus-valgus laxity at different flexion angles was independent of insert geometry. A valgus force in weightbearing conditions led to significantly more medial laxity (1°-3° opening) in the native knee at 45° and 90° flexion compared with the reconstructed knee for all flexion angles.

CONCLUSIONS

Insert geometry seems to have a limited effect with respect to AP translation and VV laxity, in the well-balanced PCL-retaining TKA with an anatomical femoral component. Secondly, AP translation and VV laxity in the reconstructed knee approximated the laxity of the native knee.

Can tibio-femoral kinematic and kinetic parameters reveal poor functionality and underlying deficits after total knee replacement? A systematic review

BACKGROUND

Extensive efforts have been made to understand joint kinematics and kinetics in total knee arthroplasty (TKA) in subjects with satisfactory outcomes during daily functional activities and clinical tests, but it remains unclear whether such movement characteristics hold the potential to indicate the underlying aetiology of unsatisfactory or bad TKA outcomes.

PURPOSE

To investigate which kinematic and kinetic parameters assessed during passive clinical tests and functional activities of daily living are associated with poor functionality and underlying deficits after total knee replacement.

METHODS

We focused on studies characterizing the kinematic or kinetic parameters of the knee joint that are associated with poor clinical outcome after TKA. Seventeen articles were included for the review, and kinematic and kinetic data from 719 patients with minimal follow up of 6 months were extracted and analyzed.

RESULTS

Passive posterior translation at 90°flexionexhibited good potential for differentiating stable and unstable TKAs. Anterior-posterior (A-P) translation of the medial condyle at 0-30° and 30-60° flexion, A-P translation of the lateral condyle at 60-90°during closed chain exercises, as well asknee extension moment during stair ascent and descent, knee abduction moment during stair descent, knee internal rotation moment and plantar flexion moment during walking, 2ndpeak ground reaction force during stair ascent and walkingshowed the greatest promise as functional biomarkers for a dissatisfied/poor outcome knee after TKA.

CONCLUSION

In this study, we systematically reviewed the state-of-the-art knowledge of kinematics and kinetics associated with functional deficits, and found 11 biomechanical parameters that showed promise for supportingdecision making in TKA.

Management of instability after primary total knee arthroplasty: an evidence-based review

Background

Instability is one of the most common reasons for revision after a total knee replacement. It accounts for 17.4% of all single-stage revision procedures performed in the UK National Joint Registry. Through a careful patient evaluation, physical assessment and review of investigations one can identify the likely type of instability.

Aims

To critically examine the different types of instability, their presentation and evidence-based management options.

Method

A comprehensive literature search was conducted to identify articles relevant to the aetiology and management of instability in total knee replacements.

Results

Instability should be categorised as isolated or global and then, as flexion, mid-flexion, extension or recurvatum types. By identifying the aetiology of instability one can correctly restore balance and stability.

Conclusion

With careful judgement and meticulous surgical planning, instability can be addressed and revision surgery can provide patients with successful outcomes.

Improving radiographic patello-femoral tracking in total knee arthroplasty with the use of a flexion spacer: a case-control study

PURPOSE

The purpose of this study was to compare the effectiveness of a flexion spacer in the clinical and radiological outcomes of patients who underwent total knee arthroplasty (TKA) and to compare these patients to a group of patients subjected to the same type of surgery but without the use of a flexion spacer. It was hypothesized that patients who underwent TKA using a flexion spacer would have better clinical and radiological outcomes than those without a flexion spacer in both short- and medium-term follow-ups.

METHODS

A consecutive series of patients undergoing TKA were included, yielding 20 patients in the study group. The control group was identified from the consultant database of the senior author, yielding 21 patients who underwent the same operation. All 41 patients received a Vanguard Knee System (Zimmer-Biomet, Warsaw, Indiana, USA). Cases were defined as those patients who had undergone TKA using a flexion spacer device for gap balancing; controls were defined as patients who had undergone TKA without the support of a flexion spacer device. Patients were clinically and radiographically evaluated at two consecutive follow-ups: T₁-13.1 ± 1.3 months and T₂-108 ± 6 months. Clinical evaluation was performed using the Knee Society Scoring System and the Western Ontario, McMaster Universities Osteoarthritis Index score. Radiographic evaluation included the femoral angle (α), the tibial angle (β), the sagittal femoral (γ) angle and the tibial slope (δ). Furthermore, the lateral patellofemoral angle (LPFA) and the Caton-Deschamps index were evaluated.

RESULTS

No statistically significant clinical differences were found between the two groups at T₁ and T₂; moreover, the clinical outcomes of the two groups were stable between the two follow-ups, with no significant improvement or worsening. Radiographic evaluation showed no difference in the two groups between T₁ and T₂; the only significant radiographic difference between the two groups concerned the LPFA (both at 30° and 60°) at each follow-up, which was significantly greater in cases than in controls (p = 0.001).

CONCLUSIONS

The current study demonstrates that the use of a flexion spacer significantly improves radiographic patello-femoral tracking, although no significant clinical differences were found between the two groups.

LEVEL OF EVIDENCE

Case-control study, level III.

Functional assessment of the anterior cruciate ligament in knee osteoarthritis

The purpose of this study was to evaluate anterior cruciate ligament (ACL) function in knee osteoarthritis (OA) and clarify the relationship of MRI and arthroscopic findings with ACL function. Eighty patients with knee OA were evaluated for anterior knee joint laxity, Kellgren-Lawrence grade, MRI ACL grade, arthroscopic ACL grade, osteophytes, and meniscus tears. ACL function was significantly correlated with osteophyte scores and medial and lateral meniscus tears. The MRI ACL grade was strongly correlated with the arthroscopic ACL grade, and anterior knee joint laxity decreased as the grades increased, suggesting a decrease in the elasticity of degenerated ACLs.

Differences in patient-reported outcomes between medial opening-wedge high tibial osteotomy and total knee arthroplasty

PURPOSE

To compare patient subjective satisfaction between medial opening-wedge high tibial osteotomy (HTO) and total knee arthroplasty (TKA).

METHODS

This study enrolled 110 knees, including comprising 49 knees in the HTO group, and 61 knees in the TKA group. We assessed the overall satisfaction using a three-point questionnaire. The satisfaction questionnaire included three questions: (1) How satisfied are you with the results of your knee surgery? (2) How satisfied are you with your most recent knee surgery for reducing your pain? and (3) How satisfied are you with your most recent knee surgery for improving your ability to perform functions? Furthermore, we assessed knee pain and function by using the Knee Society Function Score (KSS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) systems.

RESULTS

Overall, 93.8% of patients from the HTO group and 95.1% from the TKA group indicated subjective satisfaction (very satisfied and satisfied) with their surgeries. For pain relief, the HTO group showed significantly better outcomes for overall satisfaction (p = 0.04 in walking on a flat surface and p = 0.02 in going upstairs or downstairs). For restored function, the HTO group scored significantly better on ascending stairs than the TKA group (p = 0.007). Functional outcomes using the KSS scoring system did not show significant differences between the two groups. The KOOS pain score was significantly higher in the TKA group (89.9 ± 6.4) than in the HTO group (80.3 ± 12.5).

CONCLUSION

HTO and TKA have comparable outcomes with respect to overall patient satisfaction.

LEVEL OF EVIDENCE

Level III, therapeutic case series.

Investigation of the effect of intraoperative mediolateral stability on postoperative sagittal stability after bi-cruciate stabilized total knee arthroplasty

Purpose

This study investigated the effect of mediolateral stability on sagittal stability in bi-cruciate stabilized total knee arthroplasty.

Method

This study included 59 patients. We intraoperatively assessed the component gap with a joint distraction force of 60 N for each compartment. Immediately after surgery, sagittal stability was assessed using an arthrometer.

Result

The intraoperative medial joint laxity at 30° of flexion was significantly correlated with postoperative anteroposterior translation (r = 0.276, p < 0.05).

Conclusion

This study demonstrated the effect of intraoperative mediolateral stability effect on postoperative sagittal stability. Improving medial stability may enhance postoperative sagittal stability.

Comparison of intraoperative kinematics and their influence on the clinical outcomes between posterior stabilized total knee arthroplasty and bi-cruciate stabilized total knee arthroplasty

BACKGROUND

Of all the intraoperative kinematic parameters recorded using navigation systems, femorotibial rotational alignment is reportedly associated with the clinical outcomes of cruciate retaining and posterior stabilized (PS) total knee arthroplasty (TKA). However, to our knowledge, there are no reports on the relationship of newly designed bi-cruciate stabilized (BCS) TKA and intraoperative rotational kinematics. We aimed to clarify and compare the relationships between the intraoperative kinematics and clinical outcomes of BCS TKA and PS TKA.

METHODS

We compared the intraoperative rotational kinematics and clinical outcomes at two years postoperatively of 56 BCS TKA patients and 55 PS TKA patients. Further, we evaluated the relationship between the femorotibial rotational kinematics and clinical outcomes.

RESULTS

The maximum flexion angle and the pain subscale of the Knee injury and Osteoarthritis Outcome Score (KOOS) in BCS TKA were significantly better than those in PS TKA. The intraoperative kinematic data of BCS TKA showed "screw-home" movement, while that of PS TKA did not show this movement. The rotational angular differences between at maximum flexion angle and at 60° flexion of BCS TKA showed positive correlations with the improvement of KOOS pain, symptom, activity of daily living and sports subscales. The rotational angular differences between at maximum flexion angle and at 30° flexion in PS TKA showed positive correlations with the maximum flexion angle.

CONCLUSION

Intraoperative femorotibial rotational kinematics and its influence on the clinical outcomes were different between BCS and PS TKA. BCS TKA showed more normal-like kinematics and better clinical results than PS TKA.

No difference in the anteroposterior stability between the GRADIUS and multi-radius designs in total knee arthroplasty

BACKGROUND

This retrospective study aimed to compare stability and clinical and radiological outcomes of total knee arthroplasty (TKA) for the GRADIUS and multi-radius femoral designs after minimum of two-year follow-up.

METHODS

A total of 142 patients who underwent TKA using ATTUNE posterior stabilized (PS) implants (68 patients, GRADIUS group) or Persona PS implants (74 patients, multi-radius group) for degenerative osteoarthritis were included. After an average of 2-year follow-up, the anteroposterior (AP) stability at 30°, 60°, and 90° was measured using KT 2000 device and compared between the two groups. The clinical outcome measurements included range of motion (ROM) of the knee, patient-reported outcomes and anterior knee pain (AKP). For the clinical evaluation of mid-flexion instability, pain was evaluated using the visual analog scale (VAS) score recorded during climbing up or going down stairs. The radiolucent lines on knee radiographs obtained at final follow-up were evaluated and compared between two groups.

RESULTS

The average AP stability at 30° knee flexion was 5.7 mm in the GRADIUS group and 5.9 mm in the multi-radius group; however, the difference was not significant. The AP stability at 60° and 90° knee flexion was also similar in both groups. There were no significant differences in the ROM, patient-reported outcomes at follow-up, incidence of AKP and VAS scores between the two groups. There were no differences in the incidence of radiolucency around the components between the two groups.

CONCLUSION

The GRADIUS design did not show any advantage with respect to the stability or clinical outcomes compared with the multi-radius design in TKA.

Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees

PURPOSE

Both coronal and sagittal laxity of well-functioning knees after total knee arthroplasty (TKA) was examined, and the correlations between the joint laxity and the clinical outcomes were analyzed to clarify the adequate joint laxity for the prosthesis, and the relationship between the laxity and the outcomes.

METHODS

Forty well-functioning TKA knees with a high-flexion posterior-stabilized (PS) prosthesis were studied. All patients were diagnosed as having osteoarthritis with varus deformity and were followed up for 2 years or more. The coronal and sagittal laxity was assessed at extension and flexion, and the correlations between the joint laxity and the clinical outcomes were evaluated.

RESULTS

The varus and valgus laxity averaged 5.6 ± 1.8° and 3.6 ± 1.2° at 10° knee flexion, and 7.4 ± 5.1° and 3.6 ± 2.7° at 80° knee flexion, respectively, and the AP laxity at 30° and 75° knee flexion averaged 8.7 ± 3.6 mm and 6.6 ± 2.3 mm, respectively. Knee flexion angle correlated with the joint laxity, while the other outcomes including patient-reported pain and instability were adversely affected by the greater laxity.

CONCLUSIONS

This study exhibited the importance of consistent medial laxity both at extension and flexion, which averaged 3.6°. Care should be taken to maintain the medial stability and to obtain adequate laxity both at extension and flexion during surgery. A few degrees of medial tightness can be allowed to achieve excellent clinical results after TKA for preoperative varus knees.

LEVEL OF EVIDENCE

Therapeutic study, Level III.

Effect of increased posterior tibial slope on the anterior cruciate ligament status in medial open wedge high tibial osteotomy in an uninjured ACL population

PURPOSE

The purpose of this study was to clarify the relationship between posterior tibial slope angle (PTSA) and anterior cruciate ligament (ACL) status in medial open wedge high tibial osteotomy (OWHTO). Our hypothesis was that even though OWHTO may improve anteroposterior laxity of the knee, an increase in PTSA after OWHTO would be associated with ACL degeneration.

METHODS

Seventy-five patients treated with OWHTO were retrospectively analyzed. PTSA were evaluated radiographically pre- and postoperatively. The ACL was evaluated during the index arthroscopy at the time of OWHTO and a second-look arthroscopy during the plate removal, and scored from 1 (normal ACL) to 4 (complete tear). An anterior tibial translation (ATT) test was performed.

RESULTS

The mean time period from the index to second-look arthroscopy was 15.0±4.4months. PTSA significantly increased from 5.3±3.4° preoperatively to 7.5±4.0° postoperatively (p<0.001). The average ACL score significantly increased from 1.9±0.5 at the index arthroscopy to 2.2±0.5 at the second-look arthroscopy (p=0.0025). The average ATT on the operated side significantly decreased from 7.1±2.6mm preoperatively to 5.3±2.3mm at the second-look arthroscopy (p<0.0001). There was a significant positive correlation between the increase in PTSA and the change of ACL grade [correlation coefficient (r)=0.221, p<0.05].

CONCLUSION

Even though OWHTO reduces anteroposterior knee laxity, an increase in PTSA is associated with ACL degeneration. It is important for the surgeon to avoid an increase in PTSA during the intervention to prevent ACL degeneration after OWHTO.

LEVEL OF EVIDENCE

IV, therapeutic retrospective case series.

ACL degeneration after an excessive increase in the medial proximal tibial angle with medial open wedge high tibial osteotomy

PURPOSE

This study examined the influence of the mechanical medial proximal tibial angle (MPTA) on anterior cruciate ligament (ACL) degeneration following open wedge high tibial osteotomy (OWHTO). It was hypothesised that an excessive increase in MPTA would be associated with ACL degeneration following OWHTO.

METHODS

Seventy-four knees treated with OWHTO were retrospectively examined. Arthroscopic ACL grading [0 (intact) to 4 (complete rupture)], anterior tibial translation (ATT) test at the time of OWHTO with the index arthroscopy and at plate removal with the second-look arthroscopy, clinical assessments using the Knee Society Score (KSS), and radiographic evaluations of MPTA were performed. The relationship between MPTA and the ACL condition was analysed using Spearman's correlation.

RESULTS

The time from the index arthroscopy to the second-look arthroscopy was 15.0 ± 4.4 months; the total follow-up was 31.0 ± 6.5 months. ACL grade significantly increased from 0.6 ± 0.8 (index arthroscopy) to 1.1 ± 1.2 (second-look arthroscopy) (p < 0.0018). ATT on the operated side significantly decreased from 7.1 ± 2.6 mm preoperatively to 5.3 ± 2.3 mm at the time of plate removal (p < 0.001). No significant difference was observed in KSS for ACL grades in the steady and progression groups. Changes in MPTA from the preoperative to postoperative period were significantly higher in the progression group (p = 0.0155). Changes in ACL grades were significantly correlated with preoperative MPTA and changes in MPTA (r = - 0.365 and 0.343, respectively; p < 0.01).

CONCLUSIONS

Excessively increased MPTA led to ACL degeneration following OWHTO. ACL degeneration was not associated with short-term clinical outcomes. Excessive correction of MPTA should be avoided to prevent ACL degeneration following OWHTO.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Relationship between outcome scores and knee laxity following total knee arthroplasty: a systematic review

Background and purpose - Instability following primary total knee arthroplasty (TKA) is, according to all national registries, one of the major failure mechanisms leading to revision surgery. However, the range of soft-tissue laxity that favors both pain relief and optimal knee function following TKA remains unclear. We reviewed current evidence on the relationship between instrumented knee laxity measured postoperatively and outcome scores following primary TKA. Patients and methods - We conducted a systematic search of PubMed, Embase, and Cochrane databases to identify relevant studies, which were cross-referenced using Web of Science. Results - 14 eligible studies were identified; all were methodologically similar. Both sagittal and coronal laxity measurement were reported; 6 studies reported on measurement in both extension and flexion. In knee extension from 0° to 30° none of 11 studies could establish statistically significant association between laxity and outcome scores. In flexion from 60° to 90° 6 of 9 studies found statistically significant association. Favorable results were reported for posterior cruciate retaining (CR) knees with sagittal laxity between 5 and 10 mm at 75-80° and for knees with medial coronal laxity below 4° in 80-90° of flexion. Interpretation - In order to improve outcome following TKA careful measuring and adjusting of ligament laxity intraoperatively seems important. Future studies using newer outcome scores supplemented by performance-based scores may complement current evidence.

In vivo kinematics of gait in posterior-stabilized and bicruciate-stabilized total knee arthroplasties using image-matching techniques

PURPOSE

This study aimed to evaluate the effects of two types of total knee arthroplasty (TKA) designs: posterior-stabilized (PS) and bicruciate-stabilized (BCS) on in vivo kinematics during gait.

METHODS

Continuous X-ray images of the gait were taken using a flat panel detector for 23 PS and BCS TKAs. We analyzed the tibiofemoral implant flexion angle, anteroposterior (AP) translation, axial rotation, and anterior/posterior cam-post contact using image-matching techniques.

RESULTS

Double knee actions were demonstrated for the PS and BCS design (35 and 61%, respectively, p = 0.08). The tibiofemoral AP positions were significantly more posterior at peak extension (- 1.7 ± 2.2 and 1.0 ± 2.5 mm, respectively, p < 0.01) and anterior at peak flexion (1.3 ± 2.3 and - 0.8 ± 2.8 mm, respectively, p = 0.01) for the PS design than for the BCS design, with a significant difference in AP translation (3.0 ± 3.9 mm anterior and 1.7 ± 2.8 mm posterior, respectively, p < 0.01). Anterior/posterior tibial post contacts were found in 83/4% and 74/30% for the PS and BCS designs, respectively, with a significant difference in posterior contact (p = 0.72/0.04, respectively).

CONCLUSION

The knee flexion pattern, tibiofemoral AP translation, axial rotation, and cam-post contact during gait varied, depending on the type of implant, the PS and BCS designs.

Pyruvate Kinase M2 Modulates the Glycolysis of Chondrocyte and Extracellular Matrix in Osteoarthritis

Pyruvate kinase M2 (PKM2) has been wildly verified to modulate glycolysis in tumor cells. However, the role of PKM2 on the glycolysis of osteoarthritis (OA) chondrocytes is still unclear. In present study, we investigate the function of PKM2 on OA chondrocyte glycolysis and the collagen matrix generation in vitro. Results showed that PKM2 was upregulated in OA chondrocytes compared with healthy control chondrocytes. In OA chondrocytes, ATP expression was lower compared with healthy control chondrocytes. Loss-of-function experiment showed that PKM2 knockdown mediated by lentivirus transfection could significantly suppress the glucose consumption and lactate secretion levels and decrease glucose transporter-1 (Glut-1), lactate dehydrogenase A (LDHA), and hypoxia inducible factor 1-alpha (HIF-1α), indicating the inhibition of PKM2 knockdown on glycolysis. Moreover, Cell Counting Kit-8 (CCK-8), flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay showed that PKM2 knockdown inhibited OA chondrocyte proliferation and promoted the apoptosis. Western blot and immunocytochemical staining showed that PKM2 knockdown downregulated the expression levels of COL2A1 and SOX-9. In summary, our results conclude that PKM2 modulates the glycolysis and extracellular matrix generation, providing the vital role of PKM2 on OA pathogenesis and a novel therapeutic target for OA.

Evaluation of a multimodal pain therapy concept for chronic pain after total knee arthroplasty: a pilot study in 21 patients

Background

In spite of the improvement of many aspects around Total knee arthroplasty (TKA), there is still a group of 10% to 34% of patients who is not satisfied with the outcome. The therapy of chronic pain after TKA remains a medical challenge that requires an interdisciplinary therapy concept. The aim of this prospective pilot study was to evaluate the efficacy of a multimodal pain therapy in chronic complaints after TKA.

Methods

In a prospective cohort pilot study, we included patients with chronic pain after TKA who obtained in-patient care, especially multimodal pain therapy (MMPT), for at least 10 days. Essential elements of this therapy concept were physiotherapy, pain medication therapy, topical application of ketamine, local infiltration and Traditional Chinese Medicine. Patients with varying causes of complaints were excluded in advance. Before the start of the study all test persons were informed and gave their written consent. Moreover, each patient was examined and questioned at hospital admission, discharge and at its first as well as second follow-up. Additionally, knee joint mobility and stability were investigated at all examination times.

Results

From 03/07/2016 to 07/14/2016, 21 patients were included in the pilot study. 52% of the considered population were female (11 persons). The median age was 65 years (45–79 years) and the median stay in hospital amounted 9 days (8–14 days). The first follow-up was scheduled after six weeks (median: 38 days, 30–112 days) and the second one after six months (median: 8 months, 7–12 months). The number of patients of the first follow-up was 17 out of 21 (19% drop out). The drop out of the last follow-up accounted for 33%. All patients benefit from the presented applications and therapies with regard to pain, function and range of motion. Especially, during the period of in-patient treatment, nearly all patients have improved in all terms. However, during the first follow-up clear deteriorations occurred in all areas, which stagnated up to the second follow-up. The range of motion has even worsened slightly.

Conclusions

With the presented pilot study on multimodal in-patient therapy of chronic complaints due to TKA, the improvement of pain, function and mobility could be verified, especially during the stationary stay. Even though the results deteriorate during the follow-up period, they did never relapse to their initial level. In order to ensure an effective treatment, a clear diagnostic algorithm is essential, by which treatable causes, such as low-grade infections or loosenings, are safely excluded. Further prospective studies are necessary to obtain precise statements on prospects of success of our therapy plan.