Evaluation of anatomic references for tibial sagittal alignment in total knee arthroplasty

The authors aimed to demonstrate the relationship between the sagittal mechanical axis of the tibia and other reference axes of the tibia and fibula in patients with advanced osteoarthritis of the knee joints, and then to identify a reliable landmark in order to minimize posterior tibial slope measurement errors. We evaluated 133 osteoarthritic knees with neutral or varus deformity in 64 female and 8 male patients. Axial computed tomographic images of whole tibiae including knee and ankle joints were obtained and reconstructed using 3-dimensional imaging software. Angles between the mechanical axis (MA), the tibial anatomical axis (TAA), the anterior tibial cortex (ATC) and the fibular shaft axis (FSA) were measured, and then medial and lateral tibial slope angles were measured using all axes. Mean angles between MA and the other anatomical reference lines (TAA, ATC and FSA) were 0.9, 2.2 and −2.1°, respectively. The mean values of lateral tibial slopes with respect to MA, TAA, ATC and FSA were 8.7, 10, 12 and 7.3, respectively, and their intra- and inter-observer reliabilities were higher than those of medial tibial slopes. Although posterior tibial slope change markedly according to the reference axis used, the axes used in conventional TKA showed significant correlations with each other, and thus, may be used safely if differences with the mechanical axis are considered. Moreover, the lateral tibial slope might have advantages over the medial tibial slope in terms of restoration of the natural tibial slope.     

Kinematic alignment is a possible alternative to mechanical alignment in total knee arthroplasty

Purpose

A systematic review was conducted to answer the following questions: (1) Does kinematically aligned (KA) total knee arthroplasty (TKA) achieve clinical outcomes comparable to those of mechanically aligned (MA) TKA? (2) How do the limb, knee, and component alignments differ between KA and MA TKA? (3) How is joint line orientation angle (JLOA) changed from the native knee in KA TKA compared to that in MA TKA?

Methods

Nine full-text articles in English that reported the clinical and radiological outcomes of KA TKA were included. Five studies had a control group of patients who underwent MA TKA. Data on patient demographics, clinical scores, and radiological results were extracted. There were two level I, one level II, three level III, and three level IV studies. Six of the nine studies used patient-specific instrumentation, one study used computer navigation, and two studies used manual instrumentation.

Results

The clinical outcomes of KA TKA were comparable or superior to those of MA TKA with a minimum 2-year follow-up. Limb and knee alignment in KA TKA was similar to those in MA TKA, and component alignment showed slightly more varus in the tibial component and slightly more valgus in the femoral component. The JLOA in KA TKA was relatively parallel to the floor compared to that in the native knee and not oblique (medial side up and lateral side down) compared to that in MA TKA. The implant survivorship and complication rate of the KA TKA were similar to those of the MA TKA.

Conclusion

Similar or better clinical outcomes were produced by using a KA TKA at early-term follow-up and the component alignment differed from that of MA TKA. KA TKA seemed to restore function without catastrophic failure regardless of the alignment category up to midterm follow-up. The JLOA in KA TKA was relatively parallel to the floor similar to the native knee compared to that in MA TKA. The present review of nine published studies suggests that relatively new kinematic alignment is an acceptable and alternative alignment to mechanical alignment, which is better understood. Further validation of these findings requires more randomized clinical trials with longer follow-up.

Level of evidence

Level II.

     

Comparison of alternate references for femoral rotation in female patients undergoing total knee arthroplasty

Purpose

Accurate rotational alignment of the femoral component is of vital importance for successful total knee arthroplasty (TKA). Two anatomical references located on the anterior femur were recently introduced. To determine which is more reliable reference axis for the femoral component rotation in female patients receiving TKA, the trochlear anterior line was compared with the femoral anterior tangent line.

Materials and methods

Preoperative computed tomography in 76 patients receiving TKA for varus deformity was performed, and the images were reconstructed into three-dimensional models. The trochlear anterior line was defined as the line connecting the most anterior portion of the lateral and medial femoral condyles and the femoral anterior tangent line as the line parallel to distal anterior femoral surface. The two angles between these reference axes and the surgical transepicondylar axis (TEA) in three-dimensional images (trochlear anterior line/TEA, femoral anterior tangent line/TEA) were measured. The correlation between these two angles was computed. We investigated to see whether a significant difference in variance existed.

Results

The trochlear anterior line was internally rotated by 6.1° ± 2.5° with respect to TEA, whereas the femoral anterior tangent line by 9.5° ± 3.8°. The trochlear anterior line was externally rotated by 3.4° ± 3.3° with respect to the femoral anterior tangent line. There was a significant correlation between the trochlear anterior line/TEA and the femoral anterior tangent line/TEA.

Conclusions

The variance of the trochlear anterior line/TEA was significantly smaller than that of the femoral anterior tangent line/TEA demonstrating a more consistent distribution. When conventional reference axes such as the posterior condylar axis or the anteroposterior axis are unclear or differ, surgeons can rely on these alternative references. When trochlear anterior line and femoral anterior tangent line contradicts, the former might be more reliable for the rotational alignment of the femoral component in female patients.

Level of evidence

Case series with no comparison group, Level IV.

     

The accuracy of the extramedullary and intramedullary femoral alignment system in total knee arthroplasty for varus osteoarthritic knee

Purpose

The intramedullary (IM) femoral alignment system does not alway guarantee accuracy of the component position in the total knee arthroplasty (TKA). In some cases, the extramedullary (EM) femoral alignment system in total knee arthroplasty (TKA) is a useful alternative surgical option to adjust femoral component alignment. In the EM technique, accuracy of the femoral head center location is mandatory. The purpose of this prospective randomized study was to compare the alignment after TKA using two different femoral alignment systems.

Methods

From January 2009 to December 2009, 91 patients (106 knees) with osteoarthritis underwent TKA. The IM femoral alignment system was used in 50 TKAs, and the EM system was used in 56 TKAs. We measured the coronal, sagittal alignment of the femoral component, and overall alignment from full-length standing. Anteroposterior radiographs were taken 1 year after surgery.

Results

The overall limb alignment was 0.2° ± 1.9° varus in the EM group and 1.1° ± 1.9° valgus in the IM group (p = 0.001). The coronal alignment of the femoral component was 90.0° ± 1.1° in the EM group and 90.3° ± 1.2° in the IM group, not statistically different (n.s.). The sagittal alignment of the femoral component was 2.3° ± 1.7° in the EM group and 2.5° ± 1.0° in the IM group (n.s.). Clinically acceptable overall limb alignment was achieved in 91.1 % of EM group and 84.0 % of IM group (n.s.).

Conclusion

The present study suggests that by applying our EM technique that uses a newly designed mechanical axis marker system, the alignment of the femoral component and overall limb alignment is reliable and at least as accurate as the standard IM technique.

Level of evidence

I.     

Proprioception after bicruciate-retaining total knee arthroplasty is comparable to unicompartmental knee arthroplasty

Purpose

Rising expectations in functional performance of total knee joints are inciting further improvement of knee arthroplasty implants. From a patient-centred view, bicruciate-retaining models provide a more natural feeling knee. However, there is no evidence of functional advantage for these implants. The aim of this study was to evaluate balance ability as a measure of proprioception in patients with a bicruciate-retaining total knee arthroplasty.

Methods

A prospective, controlled trial was conducted to compare balance ability in 60 patients after arthroplasty of the knee for osteoarthritis. We compared patients with a bicruciate-retaining knee arthroplasty (BCR group) to a control group of patients with a medial unicompartmental knee arthroplasty (UKA group) and another control group of patients with a posterior stabilized total knee arthroplasty (PS group). The patient population comprised 30 women (50.0 %) and 30 men in three cohorts of 20 each. The mean age was 62.1 ± 8.0 years (range 43–78). Patients were evaluated preoperatively and 9 months post-operatively. The evaluation included clinical, radiological, and balance testing—a single-leg stance with eyes closed compared to eyes open. The difference in area of sway between eyes closed and eyes open represents static balance ability after knee arthroplasty.

Results

Perioperative data showed that there was no intra-operative fracture of the intercondylar eminence. There was a decreased post-operative knee extension 9 months post-operative in the BCR group, which was not clinically relevant in any case. We recorded a lower difference in the area of sway between eyes closed and eyes open (ΔA _(ec–eo)) for the BCR group (p = 0.01) and the UKA group (p = 0.04) compared to the PS group.

Conclusions

This study found superior static balance ability after preservation of both cruciate ligaments in arthroplasty of the knee, indicating superior proprioceptive function. Hence, BCR implants could provide improved functional properties. Superior proprioceptive function of bicruciate-retaining implants can be an important factor in implant selection. Further prospective, randomized studies to investigate kinematics and long-term survivorship of bicruciate-retaining implants are needed.

Level of evidence

II.

     

Accuracy of anatomical references used for rotational alignment of tibial component in total knee arthroplasty

Purpose  

This study aimed to research which was the most reliable of the four techniques based on local anatomic markers used to determine tibial component rotation in total knee arthroplasty, and whether the markers varied in knees with varus deformity.     

The dorsal pedis artery as a new distal landmark for extramedullary tibial alignment in total knee arthroplasty

Purpose

It is better to use multiple anatomical landmarks to reduce errors in component alignment in total knee arthroplasty. Therefore, it is worthwhile to find a new landmark that can be used as an addition to conventional ones. Herein, we assessed the dorsal pedis artery as a new distal landmark for extramedullary tibial alignment.

Methods

Fifty-two ankles in patients undergoing total knee arthroplasty and 10 ankles in normal controls were included. Color Doppler ultrasonography was used to locate the dorsal pedis artery at the level of the ankle joint. Conventional landmarks, including the tibialis anterior tendon, the extensor hallucis longus tendon, the extensor digitorum longus tendon, and the malleolar centre, were also located on ultrasound images. The distances between the ankle centre and each landmark were measured and compared.

Results

The dorsal pedis artery was absent in 2 patients and impalpable but visible with ultrasonography in other 2 patients. The dorsal pedis artery was located anatomically closest to the ankle centre in patients (0.4 ± 3.4 mm lateral). Statistical analysis showed that the dorsal pedis artery, the extensor hallucis longus tendon, and the malleolar centre were located significantly closer to the ankle centre comparing with the extensor digitorum longus tendon and the tibialis anterior tendon in both patients and controls (p < 0.001).

Conclusions

As long as the dorsal pedis artery exists, it can be used as an addition to the conventional landmarks in total knee arthroplasty. Using this new landmark will help reduce errors in coronal plane alignment of tibial component.

Level of evidence

II.     

全膝关节置换术后的康复治疗

全膝关节置换术（total knee arthroplasty,TKA）现已得到广泛应用,术后的康复治疗对全膝关节置换术（TKA）的总体效果有重要影响。笔者对康复治疗在TKA的重要作用加以综述。     

Tennis after total knee arthroplasty

In this study, patients who played tennis after undergoing a total knee arthroplasty were analyzed in terms of their functional abilities and degree of satisfaction. The patients were recruited by means of a questionnaire that was sent to players from lists supplied by the United States Tennis Association. The study group consisted of 28 men and 5 women (46 total knee replacements) with a mean age of 64 years. Only 21% (7 of 33) of the patients' surgeons approved of their patients undertaking tennis activity, with 45% (15 of 33) recommending only doubles tennis. At both 1 year and a mean of 7 years after arthroplasty, players were playing both singles and doubles tennis approximately three times per week (range, one to seven). All tennis players polled were satisfied with their knee arthroplasties and their ability to resume playing tennis. Because the study patients played at a high level, future studies are needed to determine the effect of tennis on the general population, which does not play at such a uniformly high level. The long-term (15 to 20 years) effect of tennis activity on the clinical and radiologic outcome of total knee arthroplasty also needs to be determined.     

Imaging of total knee arthroplasty

Painful total knee arthroplasty (TKA) represents a diagnostic challenge for the clinician and radiologist, as there is a wide variety of potential etiologies, with a broad range of clinical presentations, and the abnormalities on imaging studies are often subtle, absent, or nonspecific. Imaging findings of normal TKA are reviewed, in addition to a variety of complications such as loosening, infection, instability, osteolysis, heterotopic ossification, extensor mechanism disruption, and fracture. Although imaging evaluation of painful TKA is usually limited to conventional radiographs and nuclear imaging, examples of the utility of computed tomography are also illustrated, and suggested imaging strategies and algorithms are discussed.     

全膝关节置换术后的功能康复训练

目的介绍全膝关节置换术后的康复训练方法，总结其效果。方法对140例行全膝关节置换术的患者，进行1年系统的康复训练，按美国特种外科医院（HSS）膝关节功能评分标准，术前膝关节评分（51．25±6．10）分，康复内容包括：肌力、肌耐力、本体感受功能、活动度、理疗、心理治疗。通过功能评分、稳定性、肌力、满意度等几方面，评价其效果。结果术后3个月，膝关节肿胀已消除，术后平均1年患膝股四头肌、胭绳肌、腓肠肌肌力均达到Ⅳ级[徒手肌力评定（MMT）分级]以上，88．33％患者均能恢复正常步态和上下楼梯。患者主观满意程度高，术后12个月膝关节功能评分（87．13±7．43）分，与术前相比，差异有统计学意义（P〈0．01）。结论对于行全膝关节置换术后患者，采用该康复方法切实有效。     

Accuracy of the second metatarsal as a landmark for the extramedullary tibial cutting guide in total knee arthroplasty

Purpose

The purpose of this study was to evaluate the accuracy of the second metatarsal (MT2) as a landmark for proximal tibial cutting in total knee arthroplasty (TKA). It was hypothesized that the accuracy of the MT2 is not high, especially in rheumatoid arthritis (RA) patients whose foot joints are apt to be involved.

Methods

Computer simulation studies on 48 RA knees and 45 osteoarthritis (OA) knees were performed. The deviations from the mechanical axis (MA) of the tibia when the guide rod was pointed toward the base of the MT2 or the distal part of the MT2 were measured.

Results

The mean deviation from MA was 0.8° ± 2.1° valgus (range 8.1°–6.3° valgus) and 1.2° ± 2.9° valgus (range 11.6°–7.9° valgus) at the base of the MT2, and at the distal part of the MT2, respectively. The outlier rate when using the base of the MT2 was lower than when using the distal part of the MT2 (12.9 vs 32.3 %, p = 0.0032). The outlier rate was equivalent in OA and RA patients (n.s.). However, foot involvement in RA patients demonstrated a trend toward significance (base of MT2 p = 0.078, distal part of MT2 p = 0.068).

Conclusions

The major clinical relevance was to raise caution about using the MT2. Surgeons should aim toward the base of the MT2, but avoid using it in RA patients with foot involvement. The accuracy of the MT2 is not high and it should be used only to supplement other landmarks.

Level of evidence

II.     

帕瑞昔布钠对全膝全髋关节置换术后镇痛的疗效分析

目的 评价帕瑞昔布钠对全膝关节置换术(total knee arthroplasty,TKA)和全髋关节置换术(total hip arthroplasty,THA)术后的镇痛效果. 方法 本研究为前瞻性、随机、双盲研究,由同一组医师完成101例TKA患者和105例THA患者,根据镇痛方式分为三组:(1)术中静脉注射帕瑞昔布钠组;(2)术中关节局部注射帕瑞昔布钠组;(3)对照组.比较术后三组的视觉模拟疼痛评分(VAS)、关节活动度(ROM)、术后直腿抬高能力和恶心、呕吐等并发症的发生率. 结果 术中静脉注射帕瑞昔布钠组和术中关节局部注射帕瑞昔布钠组在术后各时段的VAS评分和术后24 h ROM及直腿抬高能力的差异无统计学意义(P＞0.05),但均明显优于对照组(P＜0.05).使用帕瑞昔布钠后恶心、呕吐等并发症的发生率没有显著增加. 结论 术中静脉注射和术中关节局部注射帕瑞昔布钠对TKA和THA术后的镇痛效果确切,有利于患者关节功能的迅速康复,且操作简便、实用,是TKA和THA镇痛的有效方法之一.     

The femoral sulcus in total knee arthroplasty

The position of the femoral sulcus relative to the midline of the distal femoral resection in total knee arthroplasty (TKA) was studied to determine if centralized placement of the femoral component on the distal femur was justified in terms of aligning the prosthetic sulcus with the native femoral sulcus. The location of the femoral sulcus was studied in 112 consecutive patients undergoing TKA. The mean sulcus position was 0.7 mm lateral to the midline of the distal femoral resection (SD 1.4, 95% CI, 0.5–1.0 mm). However, the variation in sulcus positions ranged from 4 mm medial to 4 mm lateral to the midline. The mean sulcus position in valgus knees was 1.0 mm lateral to the midline (SD 1.8), and that in varus knees was 0.7 mm lateral to the midline (SD 1.2) (P = 0.501). It appears prudent to centre the femoral component on the native sulcus rather than the midline of the distal femoral resection, so as to ensure accurate alignment of the prosthetic sulcus with the native sulcus and to encourage normal patella tracking.     

Modular augmentation in revision total knee arthroplasty

Purpose

Controversy exists about the real effectiveness of modular augmentation to manage bone defects in revision total knee arthroplasty. The purpose of this study was to determine whether use of modular augmentation to reconstruct severe defects (1) significantly increased overall outcomes, (2) caused radiolucency or osteolysis and (3) affected mid-term survivorship of knee revisions. The hypothesis was that modular augmentation provides a good survivorship of knee revisions.

Methods

Thirty-eight consecutive revision knee arthroplasties were followed for a median follow-up period of 7 (4.5–9) years. Type 2 and 3 defects were treated with metal augments, tantalum cones and modular cementless stems. Patients were assessed using the IKS knee and function scores and the HSS score.

Results

The median IKS knee and function scores and HSS score were 34 (15–58), 19.5 (13–39) and 30 (24–60) points before the operation, respectively, and 78 (49–97), 76 (58–90) and 80.5 (64–98) points (p < 0.001) at the latest follow-up. The median knee flexion increased from 82° (31°–110°) to 116° (100°–129°) (p < 0.01). Tibial radiolucencies were observed in 2 (5.2 %) cases. Re-revision was necessary in three (7.9 %) patients.

Conclusions

Modular augmentation may reduce the need for allografting to treat severe bone defects, providing a well-functioning and durable knee joint reconstruction.

Level of evidence

Case-series study, Level IV.     

Computer-assisted revision of total knee arthroplasty

Revision total knee prosthesis still remains a difficult procedure. Particularly, challenging is the restoration of the joint line to a normal position and the attainment of correct lower limb alignment and healthy bone support for the implants. Computer assistance improves accuracy during the implantation of primary total knees. The goal of this study was to evaluate the usefulness of computer assisted surgery (CAS) in total knee prosthesis revision. We revised 15 NKII total knee arthroplasties with the Navitrack system and compared the mechanical alignment and the joint line level on pre- and postoperative radiographs. After revision, the joint line position was restored. The knee with the revision prosthesis was aligned in the frontal plan with implants fixed perpendicularly to the mechanical axis. It is possible to correctly revise knee prosthesis with computer assistance only and without having to use a conventional ancillary. We had a permanent control of the joint line position and have performed the revision surgery following the same steps as in a primary implantation.     

An alternative patellar resurfacing technique in knee replacement: patellofemoral fascial interposition arthroplasty

The present study reports the early clinical results of 38 osteoarthritic patients (38 knees) who were treated by total knee replacement in conjunction with patellofemoral fascial interposition arthroplasty (PFIA). After the femoral and tibial components were inserted, a fasciotendinous graft was harvested from the anterior surface of the quadriceps tendon and sutured around the articular surface of the patella. The patients were followed-up for a minimum of 24 months. The durability of the fascial graft was assessed radiographically by addition of a wire suture marker placed into the fascia in the first five patients. Patients were evaluated using the Hospital for Special Surgery (HSS) knee-rating system, and anterior knee pain was assessed using specific patellofemoral-related questions. The average HSS knee score improved from 61 points preoperatively to 92 points at 24 months' follow-up (P<0.001). Twenty-five patients (65.7%) had anterior knee pain preoperatively, and seven patients (18.4%) revealed anterior knee pain at their last visits (P<0.001). The position of the markers in the fascial grafts did not show any change during radiological follow-ups. Our data suggest that, PFIA provides good pain relief and it may be an alternative resurfacing technique avoiding the complications of patellar components.