Can TKA design affect the clinical outcome? Comparison between two guided-motion systems

Purpose

In a retrospective comparative analysis in patients undergoing primary guided-motion total knee arthroplasty (TKA), the authors have evaluated whether different TKA implant design would influence the clinical and functional outcomes.

Methods

Between 2007 and 2009, 227 computer-assisted primary TKAs were performed in 219 consecutive patients. Patients received one of the two different fixed-bearing guided-motion TKA designs assisted by navigation surgery: the Scorpio Non-Restrictive Geometry (NRG) knee system and the Journey Bi-Cruciate Stabilized (BCS) knee systems.

Results

Data were available for 180 patients (187 knees). No significant differences were observed between the two groups with respect to preoperative demographic characteristics, range of motion (ROM) and radiographic knee alignment. At a mean follow-up of 29 months, the Journey BCS group had higher mean Knee Injury and Osteoarthritis Outcome Score (KOOS) in all subscales and a greater ROM than the Scorpio NRG group. This difference was statistically significant for the KOOS subscales of pain (p = 0.007) and knee-related quality of life (p = 0.045), as well as for postoperative ROM (p = 0.018). Considering the overall complications, 1 patient of Scorpio NRG group (0.5 %) and 5 in Journey BCS (2.7 %) had stiffness. Anterior knee pain was reported in 4 cases of Scorpio NRG group (2.1 %). In the Journey BCS group were observed 2 cases (1.1 %) of frontal plane instability and 1 case (0.5 %) of synovitis pain.

Conclusions

The bearing geometry and kinematic pattern of different guided-motion prosthetic designs can affect the clinical–functional outcome and complications type in primary TKA.

Level of evidence

Clinical study, Level III.     

Reduced morphine consumption and pain severity with transdermal fentanyl patches following total knee arthroplasty

Purpose

To determine the effects of transdermal fentanyl patches (TFPs) for postoperative analgesia in patients undergoing total knee arthroplasty (TKA) surgery.

Methods

A randomized, double-blind, controlled trial study of 40 ASA I–III patients undergoing TKA surgery was performed under general anaesthesia. Patients were randomly divided into two groups. Group I (n = 20) received two 25 μg TFPs placed on the laterals of chest wall approximately 12 h before induction of general anaesthesia. Group II, the control group (n = 20), received placebo patches of identical size. Postoperative pain at rest was assessed with visual analogue scale (VAS) at 0, 30 min and 2, 4, 6, 12, 24, 48 and 72 h. Total rescue consumption of morphine was estimated with patient control analgesia during the first 72 h after operation. The degree of active knee flexion and incidence of side effects were also evaluated.

Results

The VAS scores at 2, 4, 6, 12, 24, 48 and 72 h were significantly less in the group I compared to the group II (p < 0.05). Total morphine consumption was significantly less in group I than in group II (p < 0.05). No significant differences were found between the groups in the postoperative active knee flexion (n.s.). Side effects were similar between the groups.

Conclusions

Transdermal fentanyl patches provide effective pain relief and decrease total rescue morphine consumption during the first 72 h after operation without additive side effects in patients undergoing TKA surgery.

Level of evidence

I.     

Posterior cruciate-retaining versus posterior stabilized total knee arthroplasty: a meta-analysis of randomized controlled trials

Purpose

To compare the outcomes between posterior cruciate-retaining and posterior stabilized total knee arthroplasty (TKA) in order to evaluate which approach is superior.

Methods

Randomized controlled trials (RCTs) comparing posterior cruciate-retaining with posterior stabilized TKA were reviewed which were published up to August 2011. Methodological quality of each included RCT was assessed using the Physiotherapy Evidence Database (PEDro) scale. The relevant data were analysed using Review Manager 5.1. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to determine the quality of the evidence.

Results

Eight RCTs involving 888 patients with 963 knee joints met predetermined inclusion criteria. The postoperative range of motion (ROM) and flexion angle were 11.07° and 2.88° higher for patients with a posterior stabilized TKA than those with a posterior cruciate-retaining TKA, respectively [weighted mean difference (WMD), ?11.07; 95 % confidence interval (CI), ?18.06 to ?4.08; p < 0.01 and WMD, ?2.88; 95 % CI, ?5.63 to ?0.12; p = 0.04]. No statistical differences were observed between the two designs for knee society pain score, extension angle, 2- and 5-year knee society score, 2- and 5-year knee society function score and complications after primary TKA.

Conclusion

Posterior cruciate-retaining and posterior stabilized TKA have similar clinical outcomes with regard to knee function, postoperative knee pain and the other complications. Prosthesis survivorship for both posterior cruciate-retaining and posterior stabilized TKA is satisfactory, and there are no differences between them at short- and middle-term follow-up.

Level of evidence

II.     

The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty

Purpose

The aim of this study was to investigate the post-operative radiological outcomes of patient-specific instrumentation (PSI) surgery versus conventional total knee arthroplasty (TKA).

Methods

Sixty patients scheduled for a primary TKA were prospectively divided into PSI or conventional technique. Coronal and sagittal radiographic long limb films were taken post-operatively. The accepted values for normal alignment were 180° ± 3° for hip-knee-ankle angle; 90° ± 3° for coronal femoral component angle or coronal tibia component angle; 0° to 3° flexion for sagittal femoral component angle and 0° to 7° posterior slope for sagittal tibia component angle.

Results

For hip-knee-ankle angle, there were 21 % more outliers in the PSI group compared to the conventional group (p = 0.045). Most of these outliers had valgus deformity in the PSI group and varus deformity in the conventional group (p = 0.045). For implant placement, there was no difference in the proportion of outliers between the two groups. There was also no difference in the duration of surgery.

Conclusions

This study showed that PSI surgery is associated with a larger proportion of outliers for lower limb alignment. PSI surgery as an alternative to conventional TKA is not advisable.

Level of evidence

II.     

A randomized double-blind clinical trial of tourniquet application strategies for total knee arthroplasty

Purpose

The optimal timing of pneumatic lower limb tourniquet application during primary elective total knee arthroplasty surgery (TKA) is a matter of debate. Most previous reports have failed to show significant differences between different tourniquet timings. The aim of the work was to determine how three strategies of lower limb pneumatic tourniquet application affect the outcome for TKA patients.

Methods

Forty-three patients who undergo TKA were randomized into one of the three groups, and 36 of these patients completed the study. The tourniquet was inflated just before incision and deflated after the hardening of the cement for twelve patients (Group 1), it was inflated just before cement application and deflated after its hardening for another twelve patients (Group 2), and it was inflated before incision and deflated after the last suture of the skin for a further twelve patients (Group 3). Fit-to-discharge criteria and six methods for calculating estimated blood loss were used.

Results

The estimated blood loss in Group 1 was lower than in Group 2, as determined by six methods of calculation (p < 0.05). Estimated blood loss in Group 3 was lower than in Group 2, as determined by one method (p = 0.050). The mobilization performance in Group 1 was better than in Group 2 (p = 0.023) and in Group 3 (p = 0.033). Group 1 was better fit to discharge than Group 3 (p = 0.030).

Conclusions

Inflation of an automatic pneumatic lower limb tourniquet before skin incision and its deflation after hardening of cement tends to give better outcomes in TKA patients during six postoperative days. The estimated blood loss was highest when the tourniquet was inflated just before cement application and deflated after its hardening.

Level of evidence

II.     

Knee flexion after total knee arthroplasty reduces blood loss

Purpose

Extensive blood loss after total knee arthroplasty (TKA) may be a potential problem since it leads to anaemia, increased need for transfusion and prolonged hospitalization. Aim of this study was to investigate the effects of postoperative knee flexion after TKA on blood loss and the need for transfusion.

Methods

One hundred consecutive patients undergoing primary TKA from 2012 to 2013 were randomizely divided into two groups. In one group, the knee was extended for the first 6 h after surgery, whereas in the other was flexed at 90° for the same time. Two doses of endovenous tranexamic acid were administered in all subjects. Patients were homogeneous for all the possible confounding factors.

Results

Calculated blood loss was 846 ± 197 (ml) in the flexion group and 1,242 ± 228 (ml) in the extension group (p < 0.05). Drop of haemoglobin levels at 24 h in the study group and the control group was 1.9 ± 0.8 (g/dl) and 3.0 ± 0.5 (g/dl), respectively (p < 0.01). Drop of haematocrit at 24 h was 4.5 ± 0.2 (%) in the flexion group and 6.7 ± 0.3 (%) in the extension group (p < 0.05). Blood transfusion was necessary in 5 patients in the control group and was not necessary in any patient of the study group. Average knee flexion at day 7 was 105° ± 4° in the flexion group and 98° ± 7° in the extension group.

Conclusion

Knee flexion at 90° after TKA, associated with the intraoperative use of tranexamic, acid is an effective method to reduce blood loss and the need for blood transfusion. The routine use of the present protocol is effective in reducing social costs and length of hospitalization of TKA procedures.

Level of evidence

Prospective comparative study, Level I.     

Patient satisfaction after total knee arthroplasty is affected by their general physical well-being

Purpose

We hypothesise that patients with a worse post-operative generic physical health, and those with a subclinical improvement, will have a greater rate of dissatisfaction with their total knee arthroplasty (TKA) despite improvement in their knee function.

Methods

Prospectively complied data for 2,330 primary TKA were used. Patient demographics, comorbidity, and pre- and post-operative (1 year) Oxford knee scores (OKS) and Short Form (SF-) 12 scores were collected. Patient satisfaction was also assessed 1 year post-operatively. The satisfaction rate of patients with a poor post-operative SF-12 physical component summary (PCS score) (≤40 points) and those with a subclinical improvement (<4 points) in the score were compared to those with a score of more than 40 and a clinically significant improvement, respectively.

Results

More than half of the patients (n = 1,220) had a poor post-operative SF-12 PCS, and a third (n = 722) had a subclinical improvement in their general physical health after TKA. These patients were more likely to be older in age, suffer with concomitant back pain, and pain in other joints, and have a significantly worse pre-operative mental well-being score (SF-12) and OKS (all p < 0.04 on regression analysis). Both groups had a clinically significant improvement in their OKS post-operatively (p < 0.001), but it was 10 and 8 points less, respectively, than those patients with a SF-12 PCS of more than 40, and a clinical significant improvement in their PCS score (p < 0.001). Logistic regression analysis demonstrated that patients who had a poor post-operative SF-12 PCS (odds ratio 7.9, p < 0.001) and those with a subclinical improvement in their general physical health (odds ratio 5.1, p < 0.001) after TKA were significantly less likely to be satisfied.

Conclusion

Despite benefitting from a significant improvement in their OKS after TKA, patients with a poor post-operative SF-12 PCS and those with a subclinical improvement in their general physical well-being are significantly less likely to be satisfied at 1 year.

Level of evidence

Retrospective comparative study, Level III.     

Range of motion after total knee arthroplasty: the effect of a preoperative home exercise program

Purpose

Preoperative range of motion (ROM) is the most important variable to determine final flexion after total knee arthroplasty (TKA). The purpose of this study was to determine whether a preoperative home exercise program could improve ROM in the arthritic knee and whether this influenced ROM and functional recovery following primary TKA.

Methods

During the period between 2005 and 2006, one hundred and twenty-two patients with gonarthrosis were included in a prospective study and randomly allocated to either the control or the treatment group. The sixty-one subjects in the treatment group underwent a 6-week home-based exercise program before TKA surgery. All one hundred and twenty-two patients were assessed before and after this exercise intervention. Postoperative assessments were at 6 weeks, 6 months and 1 year. Each evaluation included knee ROM and the Knee Society Clinical Rating System. Length of hospital stay and postoperative duration before achieving 90° of knee flexion were also recorded.

Results

Exercise program improves knee motion in the presence of gonarthrosis. After TKA, the patients in the exercise group achieved 90° of knee flexion faster and had a shorter hospital stay. There is no prolonged effect on knee motion or patient function between 6 weeks and 1 year postoperatively.

Conclusion

Preoperative exercise of the arthritic knee facilitates immediate postoperative recovery following primary TKA.

Levels of evidence

Therapeutic study, Level I.     

The influence of the tibial slope on intra-operative soft tissue balance in cruciate-retaining and posterior-stabilized total knee arthroplasty

Purpose

This study aims to make clear the influence of the tibial slope on intra-operative soft tissue balance measurements using a tensor in cruciate-retaining and posterior-stabilized total knee arthroplasty (TKA).

Methods

Forty patients with osteoarthritis of the knee received TKAs (20 cruciate-retaining TKAs and 20 posterior-stabilized TKA). Soft tissue balance was measured using an offset type tensor at 0, 10, 45, 90, 135 degrees of knee flexion. The tibial slopes were measured by post-operative lateral radiograph. The correlation between the tibial slope and values of soft tissue balance were assessed.

Results

Joint component gap at 90° (R = 0.537, p < 0.01) and 135° (R = 0.463, p < 0.05) of flexion and joint component gap change value of 90–0° (R = 0.433, p < 0.05) showed positive correlations with tibial slope in posterior-stabilized TKA. There was no relationship between the tibial slope and the value of soft tissue balances in cruciate-retaining TKA.

Conclusions

In the present study, we confirmed that increasing the tibial slope resulted in a larger flexion gap compared to extension gap in posterior-stabilized TKA. Surgeons should be aware that increasing the tibial slope is one factor responsible for widening the flexion–extension gap difference in posterior-stabilized TKA.

Level of evidence

III.     

Increased cartilage volume after injection of hyaluronic acid in osteoarthritis knee patients who underwent high tibial osteotomy

Purpose

High tibial osteotomy (HTO) is a surgical procedure used to correct abnormal mechanical loading of the knee joint; additionally, intra-articular hyaluronic acid injections have been shown to restore the viscoelastic properties of synovial fluid and balance abnormal biochemical processes. It was hypothesized that combining HTO with intra-articular hyaluronic acid injections would have benefit to improve the cartilage volume of knee joints.

Methods

Forty patients with medial compartment knee osteoarthritis (OA) were randomly placed into 1 of 2 groups. The study group (n = 20) received 2 cycles (at 6-month intervals) of 5 weekly intra-articular hyaluronic acid injections after HTO operation. The control group (n = 20) did not receive any intra-articular injections after HTO surgery. Cartilage volume (primary outcome) was assessed by magnetic resonance imaging (MRI) pre-operatively and 1 year post-operatively. Treatment efficacy (secondary outcomes) was evaluated with the Western Ontario and McMaster Universities OA Index (WOMAC) and by the comparison of the total rescue medication (paracetamol/diclofenac) used (weeks 6, 12, 24, 48).

Results

MRI studies showed a significant increase in total cartilage volume (p = 0.033), lateral femoral cartilage volume (p = 0.044) and lateral tibial cartilage volume (p = 0.027) in the study group. Cartilage volume loss was detected at the lateral tibial plateau in the control group. There were significant improvements after surgery in both groups for all subscales of WOMAC scores (p < 0.001) compared to the baseline. However, no difference was found between the two groups. The study group had significantly lower amounts of diclofenac consumption (p = 0.017).

Conclusion

Based on the findings of the present study, intra-articular hyaluronic acid injections may be beneficial for increasing total cartilage volume and preventing the loss of lateral tibiofemoral joint cartilage after HTO.

Level of evidence

Therapeutic study, Level I.     

Less blood loss under concomitant administration of tranexamic acid and indirect factor Xa inhibitor following total knee arthroplasty: a prospective randomized controlled trial

Purpose

The objective of this prospective randomized controlled trial was to assess the efficacy and safety of simultaneous application of tranexamic acid and indirect factor Xa inhibitor following total knee arthroplasty (TKA).

Methods

Seventy-two primary osteoarthritis patients undergoing unilateral TKA using fondaparinux as a basic thromboprophylaxis were randomized to receive either placebo (36 patients) or tranexamic acid (36 patients). Prophylaxis against venous thromboembolism in all patients was administered with subcutaneous doses of 2.5 mg fondaparinux for 5 days post-operatively. Post-operative retransfusion volume, allogenic transfusion volumes and drain amount were recorded for each patient. Level of haemoglobin, prothrombin time, activated partial thromboplastin time and D-dimer were also assessed. Doppler ultrasonography was performed preoperatively and 7 days after surgery.

Results

The rate of transfusion was lower in the tranexamic acid group than in the placebo group (p = 0.007). The drained blood volume during the initial 24 h and until drain removal was smaller in the tranexamic acid group than in the placebo group (p < 0.001). However, the haematologic laboratory results did not show any significant differences between the two groups. The prevalence of deep-vein thrombosis (DVT) was 4 (11.1 %) in the placebo group and 3 (8.3 %) in the tranexamic acid group (p = n.s.). There was no proximal DVT and no symptomatic pulmonary embolism in either group.

Conclusion

The use of tranexamic acid could reduce acute blood loss significantly without any adverse effect resulted from drug interaction with concomitant use of indirect factor Xa inhibitor following TKA. Therefore, simple combination of these drugs can be recommended to reduce post-operative blood loss as well as to reduce DVT following TKA.

Level of evidence

Therapeutic, Level I.     

Preoperative flexion does not influence postoperative flexion after rotating-platform total knee arthroplasty

Purpose

Preoperative range of motion (ROM) has been regarded as one of the most important factors in predicting postoperative ROM following total knee arthroplasty (TKA). Mobile-bearing TKA designs have been suggested to possibly improve the knee kinematics compared to fixed-bearing designs. The purpose of this study was to examine the difference in postoperative flexion as a function of preoperative flexion in a consecutive series of TKAs done using a posterior-stabilized rotating-platform prosthesis.

Methods

ROM was assessed in 153 consecutive TKAs done using a rotating-platform posterior cruciate-substituting design. Patients were divided into two groups based on their preoperative ROM (Group 1 < 95°, Group 2 > 95°). The Knee Society Score (KSS) and ROM were assessed preoperatively, 3 months and 12 months postoperatively.

Results

There was no difference in flexion 12 months after surgery between groups (mean 120° and 123°, respectively. n.s.). After 3 month follow-up, no increase in ROM was experienced by either group. Patients in Group 1 experienced significantly greater increases in both ROM (p < 0.001) and KSS (p < 0.05). There was no difference in the KSS at 12 months after surgery between groups.

Conclusion

In this series of patients undergoing TKA with a rotating-platform prosthesis, the preoperative ROM was not predictive of the postoperative ROM. Patients with stiff knees preoperatively may benefit from a mobile-bearing design prosthesis.

Level of evidence

Case–control study, Level III.     

Better quadriceps recovery after minimally invasive total knee arthroplasty

Purpose

The proponents of minimally invasive total knee arthroplasty (TKA) have reported better functional recovery than conventional TKA. In most of the previous studies, the results were shown with the relatively subjective methods. We investigated the objective results with a dynamometry in this prospective randomized study. It was hypothesized that minimally invasive TKA would have a better and earlier recovery of quadriceps force in terms of the objective numeric data.

Methods

Sixty-six TKAs were prospectively randomized into two groups. Thirty-three knees underwent minimally invasive TKA using mini-midvastus approach and 33 knees underwent conventional TKA using medial parapatellar approach. The quadriceps force was assessed using a dynamometer. The data were collected preoperatively and at postoperative 6 weeks, 3 months, 6 months and 1 year consecutively.

Results

The mean of quadriceps force in minimally invasive TKA group at postoperative 6 weeks was greater than conventional TKA after removing the covariate (preoperative quadriceps force) with analysis of covariance (P = 0.002), but thereafter, the difference was not significant till 1 year. Meanwhile, with repeated measures analysis of variance, conventional TKA group had greater quadriceps recovery than minimally invasive TKA group during postoperative 6 weeks to 3 months (P = 0.035). The proportion of patients unable to recover the quadriceps force to their preoperative levels by 1 year postoperatively was similar in two groups.

Conclusion

Minimally invasive TKA has benefit in quadriceps recovery at earlier rehabilitation period although catch-up recovery in conventional TKA was accelerated from the postoperative 6 weeks to 3 months. It may support the concept of early return to full activity after minimally invasive TKA, and patients might get back early to normal life.

Level of evidence

Therapeutic study, Level I.     

No difference in gait between posterior cruciate retention and the posterior stabilized design after total knee arthroplasty

Purpose

In the present study, knee joint kinematics (e.g. knee flexion/extension) and kinetics (e.g. knee flexion moments) are assessed after total knee arthroplasty (TKA) between patients implanted with either a unilateral posterior stabilized (PS) and a posterior cruciate-retaining (PCR) design. It was hypothesized that maximum knee flexion during the loading response of the stance phase is greater in patients implanted with a PS design than in patients with a PCR design. Secondarily, it was hypothesized that patients with a PS design show decreased knee flexion moments during loading, compared with patients implanted with a PCR design.

Methods

This study examined two groups of TKA patients: one group (n = 12) with a PS design in which the posterior cruciate ligament (PCL) was sacrificed and the other (n = 9) with a PCR design. Gait analysis was used in level walking before and 6–9 months after surgery, to assess knee joint kinematics and kinetics during the loading response of the stance phase.

Results

No significant differences in maximum knee flexion between the two groups were found during the loading response of the stance phase. No significant differences in knee flexion moments were found either. Although in both groups knee flexion moments increased postoperatively, this was not statistically significant. In the contralateral (nonimplanted) knees, all mean knee flexion moments decreased postoperatively for both groups, yet this was not significant.

Conclusions

The present gait analysis study showed no differences in kinematics and kinetics between the PS and the PCR TKP design. This might suggest that surgeons do not necessarily need to substitute the PCL by a PS design during TKA.

Level of evidence

Prospective comparative study, Level II.     

Dynamic KINE-MRI in patellofemoral instability in adolescents

Purpose

The impact of kinematic MRI (KINE-MRI) in the patellofemoral instability and anterior knee pain of the adolescents is rarely reported. Our special interest was to evaluate the patellofemoral joint biomechanics with KINE-MRI in adolescents with affected and unaffected knees in a case–control study.

Methods

KINE-MRI was performed in 29 adolescents (affected knee group, n = 29 and unaffected knee group, n = 26) aged 11–16 years with unilateral patellofemoral instability. For the control group, we enrolled ten healthy age- and sex-matched volunteers (healthy knee group, n = 19). The study parameters, bisect offset, lateral patellar displacement, patellar tilt angle, sulcus angle and Insall–Salvati ratio at 0, 10, 20 and 30° of flexion–extension, were measured for the affected knee patients (n = 29), unaffected knee patients (n = 26) and the healthy knee subjects (n = 19).

Results

The affected knee and the healthy knee subjects had a significant difference in the bisect offset ratio, lateral patellar displacement test and patellar tilt angle test. In these parameters, the difference between the affected knee patients and the healthy knee subjects progressively increased towards the full extension of the knee. In the affected knee and unaffected knee patients, bisect offset ratio at 0° ranged between 0.50 and 1.20 in both groups, whereas the bisect offset ratio in the healthy knee subjects ranged between 0.33 and 0.75 (p < 0.001). At the 0°, the lateral patellar displacement test ranged between 0 and 10 mm in the affected knee patients and between 0 and 35 mm in the unaffected knee patients, whereas the lateral displacement test ranged between 0 and 5 mm in the healthy knee subjects (p = 0.003). Patellar tilt angle test ranged between ?30 and 20° in the affected knee patients and between ?30 and 24° in the unaffected knee patients, and in the healthy knee subjects, the patellar tilt angle test ranged between 10 and 24° (p < 0.001).

Conclusions

The KINE-MRI was able to detect significant differences in patellofemoral joint kinematics between the patients and the healthy subjects. A new finding with clinical relevance in our work is that the unaffected knee is very similar to the dislocated knee in adolescents and this should be taken in account in rehabilitation of patients.

Level of evidence

II.     

Less femoral lift-off and better femoral alignment in TKA using computer-assisted surgery

Purpose

A comparison has been made between navigation-assisted and conventional measured resection total knee arthroplasty (TKA), under the hypothesis that navigation assistance would improve the precision and consistency of component alignment and femoral component rotation.

Methods

The following radiographic parameters were measured: mechanical femorotibial angle, coronal and sagittal component angle, and femoral component rotation. Femoral condylar lift-off was checked by axial radiographs, and thresholds for outliers were set at 1.0 mm.

Results

Clinical results obtained using Knee Society and Hospital for Special Surgery systems were not statistically different. The mean mechanical femorotibial angle was 2.2° (SD: 0.9) in the conventional group and 1.7° (SD: 0.7) in navigation group (p = 0.001). The mean coronal femoral component angle was 89.2° (SD: 2.2) in conventional group and 90.4° (SD: 1.8) in navigation group (p = 0.006). The mean transepicondylar-posterior condylar axis angle was 1.7° (SD: 0.9) in conventional group and 1.2° (SD: 0.5) in navigation group (p = 0.008). Femoral condylar lift-off greater than 1 mm occurred more frequently (p = 0.000) in conventional group.

Conclusion

Coronal plane stability and precision of femoral component rotation were impacted by navigation system. The use of a navigation system with measured resection TKA can help optimize coronal stability and parallel component position.

Level of evidence

Retrospective case control study, Level IV.     

Effect of graft tensioning on mechanical restoration in a rat model of anterior cruciate ligament reconstruction using free tendon graft

Purpose

Initial graft tensioning is important in anterior cruciate ligament reconstruction (ACLR), but its effect on graft healing is still not clear. Since all previous animal studies on graft tensioning used bone–patellar tendon–bone, this study aimed to investigate the effect of initial graft tensioning on ACLR using tendon graft.

Methods

Fifty-five Sprague–Dawley rats underwent ACLR using flexor digitorum longus tendon graft. A constant force of 2 or 4 N was applied during graft fixation. At 0, 2, and 6 weeks, knee samples were harvested (n = 6) for static knee laxity test and graft pull-out test. Histological examination was performed at 2 and 6 weeks post-injury (n = 4).

Results

At time zero, knee laxity was restored by ACLR with 2 or 4 N tensioning as compared to ACL-deficient group (p < 0.001), and the 4 N group exhibited a better restoration as compared to 2 N group (p = 0.031). At week 2 post-operation, the 4 N group still exhibited a better restoration in knee laxity (p = 0.001) and knee stiffness (p = 0.002) than the 2 N group; the graft pull-out force (p = 0.032) and stiffness (p = 0.010) were also higher. At week 6 post-operation, there was no significant difference between the 2 and 4 N group in knee laxity and graft pull-out strength. Histological examination showed that the beneficial effect of higher initial graft tension may be contributed by maintenance of graft integrity at mid-substance and reduction in adverse peri-graft bone changes in the femoral tunnel region.

Conclusions

A higher initial graft tension favours the restoration of knee laxity and promotes graft healing in ACLR using free tendon graft in the rat model.     

Computer-assisted surgery improves rotational positioning of the femoral component but not the tibial component in total knee arthroplasty

Purpose

Computer-assisted surgery (CAS) may facilitate better positioning of total knee arthroplasty (TKA) along the coronal and lateral axes; however, there are doubts as to its usefulness in the rotational plane.

Methods

This is a prospective study of 95 TKAs comparing two groups: the CAS group and the standard equipment group. The series comprises 95 cases. A radiography of the lower limb and computer tomographies (CTs) of the femoral condylar region, the proximal end of the tibia and the ankle were performed to measure rotational angulation. A month after TKA surgery, the radiography and the CTs were repeated to analyze the position of the prosthetic components in the rotational plane.

Results

In the coronal axis, both CAS and mechanical technique improved femoro-tibial alignment, but when there are preexisting deformities ≥4°, CAS obtains better results. A strong correlation (R = 0.94, p = 0.001) was observed between the mean rotational axis measured with CT in the tibial plateau and that measured from the axis of the ankle. The mean initial femoral rotation of the complete series was 6.7° and 2.7° at 1-month follow-up (p < 0.001). In the standard instrumentation group, the femoral rotation went from 6.8° to 2.3°, whereas in the CAS group the femoral rotation went from 6.5° to 3.1° (p = 0.039), which is very close to the ideal 3° angle of external rotation. Tibial rotation changed by 5.28° for the entire patient population, but no differences were found when comparing CAS and standard instrumentation.

Conclusion

CAS improves frontal alignment in TKA, especially in the presence of preoperative deformities. In the femoral component, navigation most closely replicated the ideal 3° external rotation of the femoral component, but tibial rotation did not differ when comparing CAS to standard instrumentation.

Level of evidence

II.     

Clinical value of tranexamic acid in unilateral and simultaneous bilateral TKAs under a contemporary blood-saving protocol: a randomized controlled trial

Purpose

Despite the documented blood-saving effects of tranexamic acid (TNA) in total knee arthroplasty (TKA), the question whether clinical values of TNA are identical in unilateral and bilateral TKAs remains unclear. This study was undertaken to determine the clinical values of TNA in unilateral and simultaneous bilateral TKAs under a contemporary blood-saving protocol in terms of efficacy (total blood loss and transfusion rate) and safety (the incidences of symptomatic deep vein thrombosis and pulmonary embolism).

Methods

One hundred and eighty unilateral and 146 bilateral TKA patients were randomized into TNA group or control group. In unilateral TKA patients, TNA (10 mg/kg) was administered intravenously 20 min before tourniquet deflation and repeated 3 h after surgery. In bilateral TKA patients, one more dose (10 mg/kg) was given before tourniquet deflation in the second TKA. A contemporary blood-saving protocol was applied to all patients. The TNA and control groups were compared separately in unilateral and bilateral TKA patients for the efficacy and safety variables.

Results

In unilateral TKA patients, the TNA group had less total blood loss (905 vs. 1,018 mL, p = 0.018) than the control group, but there was no difference in the allogenic transfusion rate (1 vs. 7 %, n.s.). In bilateral TKA patients, the TNA group showed no differences in total blood loss (1,282 vs. 1,379 mL, n.s.), but a significant reduction in the allogenic transfusion rate (7 vs. 27 %, p = 0.002). No symptomatic deep vein thrombosis or pulmonary embolism was found in all patients.

Conclusion

This study demonstrates that the use of TNA reduces total blood loss, but the effects on the transfusion rate can differ depending on the type of TKAs (unilateral vs. bilateral) and the blood-saving protocols.

Level of evidence

Therapeutic study, Level I (double blind randomized controlled trial).     

Efficacy of intra-articular tranexamic acid in blood loss reduction following primary unilateral total knee arthroplasty

Purpose

The surgical stress of total knee arthroplasty (TKA) procedure and the application of intra-operative pneumatic thigh tourniquet increases local fibrinolytic activity, which contributes significantly to post-operative blood loss. Tranexamic acid, an antifibrinolytic drug, is commonly used to control post-operative blood loss. The recommended mode of administration of tranexamic acid is either oral or intravenous. However, the mechanism of action of the tranexamic acid points towards the possible effectiveness it may have following local/intra-articular application. This prospective, double-blinded, randomized preliminary study evaluated the efficacy of intra-articular tranexamic acid in reducing TKA-associated post-operative blood loss.

Methods

Fifty consenting patients with osteoarthritis of the knee scheduled for primary unilateral cemented-TKA were randomly allocated to one of the two groups: Tranexamic Acid (TA) group (n = 25, 500 mg/5 ml tranexamic acid) and the control group (n = 25, 5 ml 0.9% saline). The drug and control solution were administered intra-articularly through the drain tube immediately after the wound closure. Parameters related to blood loss (drop in haemoglobin, haematocrit differential) and the drain output [volume (ml)] were compared between the two groups.

Results

On a comparative basis, TA-group obtained significant reduction in the drain output [95% CI: 360.41–539.59, p < 0.001] at 48 h post-operatively. Even though the control group received sixfold more blood transfusion than TA-group, it showed a greater drop in haemoglobin and haematocrit (p < 0.05).

Conclusions

Local application of tranexamic acid seems to be effective in reducing post-TKA blood loss as well as blood transfusion requirements.

Level of evidence

Therapeutic study, Level II.