Smart instrumentation for determination of ligament stiffness and ligament balance in total knee arthroplasty

Ligament balance is an important and subjective task performed during total knee arthroplasty (TKA) procedure. For this reason, it is desirable to develop instruments to quantitatively assess the soft-tissue balance since excessive imbalance can accelerate prosthesis wear and lead to early surgical revision. The instrumented distractor proposed in this study can assist surgeons on performing ligament balance by measuring the distraction gap and applied load. Also the device allows the determination of the ligament stiffness which can contribute a better understanding of the intrinsic mechanical behavior of the knee joint. Instrumentation of the device involved the use of hall-sensors for measuring the distractor displacement and strain gauges to transduce the force. The sensors were calibrated and tested to demonstrate their suitability for surgical use. Results show the distraction gap can be measured reliably with 0.1 mm accuracy and the distractive loads could be assessed with an accuracy in the range of 4 N. These characteristics are consistent with those have been proposed, in this work, for a device that could assist on performing ligament balance while permitting surgeons evaluation based on his experience. Preliminary results from in vitro tests were in accordance with expected stiffness values for medial collateral ligament (MCL) and lateral collateral ligament (LCL).     

Biomechanics of the knee joint in flexion under various quadriceps forces

Bioemchanics of the entire knee joint including tibiofemoral and patellofemoral joints were investigated at different flexion angles (0° to 90°) and quadriceps forces (3, 137, and 411 N). In particular, the effect of changes in location and magnitude of restraining force that counterbalances the isometric extensor moment on predictions was investigated. The model consisted of three bony structures and their articular cartilage layers, menisci, principal ligaments, patellar tendon, and quadriceps muscle. Quadriceps forces significantly increased the anterior cruciate ligament, patellar tendon, and contact forces/areas as well as the joint resistant moment. Joint flexion, however, substantially diminished them all with the exception of the patellofemoral contact force/area that markedly increased in flexion. When resisting extensor moment by a force applied on the tibia, the force in cruciate ligaments and tibial translation significantly altered as a function of magnitude and location of the restraining force. Quadriceps activation generated large ACL forces at full extension suggesting that post ACL reconstruction exercises should avoid large quadriceps exertions at near full extension angles. In isometric extension exercises against a force on the tibia, larger restraining force and its more proximal location to the joint substantially decreased forces in the anterior cruciate ligament at small flexion angles whereas they significantly increased forces in the posterior cruciate ligament at larger flexion angles.     

Preoperative varus deformity of the knee affects the intraoperative joint gap in unicompartmental knee arthroplasty

BackgroundIt is generally believed that contraction of the soft tissue structures on the medial side may occur in the knee with severe varus deformity. However, the relationship between the severity of varus deformity of the knee and the intraoperative soft tissue balance in unicompartmental knee arthroplasty (UKA) has not been well reported thus far.MethodsOne hundred and three consecutive medial UKAs were enrolled. After the femoral trial prosthesis was placed, the component gap was measured at 10° (extension) and 120° (flexion) of flexion using a UKA tensor. The pre-osteotomy gap was then calculated from the thickness of the bone cut. Paired Student’s t-test was used to compare the component gap, as well as the pre-osteotomy gap, in extension and those in flexion. The relationship between the preoperative Hip-Knee-Ankle (HKA) angle and the pre-osteotomy gap was analysed using Pearson’s correlation coefficient and simple linear regression analysis.ResultsThe component gap in extension was significantly smaller than that in flexion while the pre-osteotomy gap in extension was significantly wider than that in flexion. There was a positive correlation between the severity of varus deformation in preoperative knee and the pre-osteotomy gap in extension, while there was no correlation between the preoperative HKA angle and the pre-osteotomy gap in flexion.ConclusionsThe tension of the medial tightness does not correlate with the degree of preoperative varus deformity in UKA.     

An immunohistochemical study of enthesis development in the medial collateral ligament of the rat knee joint

The changing distributions of collagens and glycosaminoglycans have been studied at the attachments of the medial collateral ligament during postnatal development. The ligament is of particular interest because it has a fibrocartilaginous attachment to the femoral epiphysis, but a fibrous one to the tibial metaphysis. Ligaments were examined in rats killed at birth and at 2, 4, 6, 8, 10, 20, 30, 45, 60, 90 and 120 days after birth. Cryosections were immunolabelled with monoclonal and polyclonal antibodies against types I and II collagen, chondroitin 4 and 6 sulfate, dermatan and keratan sulfate. Although the ligament is attached at both ends to bones that develop from cartilage, there was a striking difference in collagen labelling. Type II collagen was only found in spicules of calcified cartilage in bone beneath the tibial enthesis after ossification had commenced, but there was a continuous band of labelling at all stages of development at the femoral enthesis. Initially, the cartilage at the femoral attachment lacked type I collagen, but by 45 days labelling was continuous from ligament to bone. Continuity of labelling was seen much earlier at the tibial enthesis, as soon as bone had formed. There were also marked changes in glycosaminoglycan distribution. Keratan sulfate was present at both entheses up to 45 days, but only at the femoral enthesis thereafter. Both attachments labelled throughout life for dermatan sulfate, but chondroitin 4 and 6 sulfate were only found at the femoral end. The results suggest that enthesial cartilage at the femoral attachment was initially derived from the cartilaginous bone rudiment but was quickly eroded on its deep surface by endochondral ossification as bone formed at the attachment site. It was replaced by fibrocartilage developing in the ligament. This mechanism allows enthesis cartilage/fibrocartilage to contribute to the growth of a bone at a secondary centre of ossification in addition to dissipating stress at the ligament-bone junction.     

伸膝装置应用解剖及其在膝关节置换术中的临床意义

目的：为全膝关节置换术（TKA）中髌骨软组织平衡提供形态学基础。方法：应用显微外科技术对12例新鲜、80例固定成人膝关节标本伸膝装置的解剖结构进行观察与测量。结果：髌前三层不同走向的纤维膜性结构包被伸膝装置。股外侧肌腱、股内侧肌、股最内侧肌与股直肌腱分别成33．50°±6．19°、54．5°±8．20°、78．60°±8．52°角。矢状面股直肌腱与髌腱成12°（3°～20°）夹角。股四头肌腱扩张部向下扩展形成髌内、外侧支持带（MPR、LPR）。内侧髌股韧带（MPFL）长（47．60±5．59）mm，宽（19．70±6．13）mm。膝关节肌为独立肌肉，是膝关节重要的滑移装置并维持髌骨内侧稳定结构。结论：TKA术中髌骨软组织平衡，关键在于准确分层缝合股最内侧肌止点和MPFL，必要时松解髌骨外上角股外侧肌腱或LPR。术中防止膝关节肌内侧束撕裂有重要意义。     

Blumensaat线对于膝关节疾病的辅助参考意义

BACKGROUND: With the development of sports medicine and research of radiologic imaging techniques, Blumensaat line (the radio-opaque line at the roof of the intercondylar notch) has been paid increasing attention. Blumensaat line is considered as measurement indexes of knee diseases. Taking advantage of the Blumensaat line, many surgeons and radiography physicians are trying to diagnose some knee diseases.     

Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex

Summary The onset latency and discharge amplitude of preprogrammed postural responses were evaluated in order to determine if the structure of synergistic activation could be altered by ligamentous laxity at the knee joint. Twelve subjects with unilateral and one subject with bilateral anterior cruciate ligament (ACL) insufficiency were tested while standing on a moveable platform. External balance perturbations (6 cm anterior or posterior horizontal displacements of the platform) were presented at velocities ranging from 15 to 35 cm/s. Perturbations were presented under the following experimental conditions: unilateral and bilateral stance, knees fully straight or flexed, and with ankle motion restricted or free. These stance, knee position, and ankle motion conditions were introduced to alter the stress transmitted to the knee joint during movement of the support surface. The automatic postural response was recorded from the tibialis anterior (T), quadriceps (Q), and medial hamstrings muscles (H) bilaterally. The normal response to an externally induced backward sway involved the automatic activation of T and Q at latencies of 80 ms and 90 ms respectively. Activation of the hamstrings in the non-injured extremity was not coupled with the postural response. Hamstrings are not typically involved in the correction posterior sway because H activation would tend to pull the center of mass further backwards. However, when the response in the ACL-deficient extremity was compared to the non-injured limb: (1) the automatic postural response in the ACL-deficient extremity was restructured to include hamstrings activation (100 ms latency), (2) H activation time was faster and less variable in the ACL-deficient limb, and (3) the ratio of H/Q discharge amplitude integrated over 100 ms and 200 ms from the onset of EMG activation showed a dominance of hamstring activity during unilateral stance on the lax limb. In addition, H/Q ratios integrated over 200 ms showed dominant hamstring activity in the ACL-deficient limb during bilateral stance. (4) Crosslimb comparisons showed greater normalized IEMG amplitudes for T, H, and Q during unilateral stance on the lax limb. These results suggest that a capsular-hamstring reflex is integrated into the existing structure of a preprogrammed postural synergy in order to compensate for ligamentous laxity. Furthermore, the generalized increase of response gain observed during perturbations of unilateral stance on the lax limb indicates that joint afference can modulate central programming to control localized joint hypermobility. A concept of postural control is discussed with respect to the capsular reflex, joint loading and displacement of the center of gravity.     

Achieving ligament stability and correct rotational alignment of the femur in knee arthroplasty: a study using the Medial Pivot knee

In a series of 90 Medial Pivot arthroplasties rotational alignment of the femur was achieved by provisionally reconstructing the lateral side of the joint and tensioning the medial side with feeler gauges. Axial CT scans were employed to measure the rotational alignment relative to surgical epicondylar axis. In valgus knees the cutting block was externally rotated to adjust for posterolateral bone loss. The mean rotational alignment of the femur was 0.6° of external rotation (S.D. 1.3, range 3° of ER to 4° of IR). The mean laxity of the medial ligament was 1 mm in flexion (SD 1, range 0–5 mm) and 0.5 mm in flexion (S.D. 0.5, range 0–2 mm) In those knees in which the medial ligament had been released the CT alignment was perfect, but when internally rotated against the hip 3–4 mm of gapping was noted.

In valgus knees the mean rotation of the femoral component was 0.8° of internal rotation (S.D. 1.5, range 1° of IR to 4° of ER). In spite of externally rotating the cutting block there was still a tendency to internally rotate the femur in some knees.

This simple technique achieves the two goals of ligament stability and correct rotational alignment in a high proportion of cases. It may be applicable to any instrument system which employs posterior referencing.     

Awareness of knee joint angle under static conditions.

The ability of subjects to match the angle of a passively positioned knee joint by active positioning of the opposite leg is nearly constant with time from 15s to 3 min. However, their ability to match this angle from memory is equally good. Thus, knowledge of joint angle after movement has ceased does not necessarily require ongoing input from tonic peripheral receptors.     

The effect of modeling cartilage on predicted ligament and contact forces at the knee

This paper describes a two-dimensional dynamic model of the human knee joint by employing cartilage model. The model outputs of rigid and deformable models are compared. The predicted tibio-femoral contact and ligament forces remain consistent whether or not a model of cartilage was included in the calculations. For both rigid and deformable contact models, the maximum contact force decreases as the amplitude of external force is increased. The effect of cartilage on ligaments' responses is insignificant except for the behavior of the anterior portion of the anterior cruciate ligament at large flexion angles.     

The postnatal development of the insertions of the medial collateral ligament in the rat knee

Bone soft tissue remodelling at the femoral and tibial insertions of the medial collateral ligament (MCL) of the rat knee was monitored at regular intervals from birth to 120 days of age in 40 Sprague Dawley rats. At birth the femoral insertion originated from the perichondrium of the epiphysis. By day 8 the perichondrium within the insertion had turned into fibrocartilage. Secondary ossification of the femoral epiphysis had progressed in the region near to the insertion site by day 15. The epiphyseal cartilage was entirely replaced by bone by day 40 except for the fibrocartilage within the insertion. After that stage, no qualitative change in zonal insertion characteristics was observed, but only increase in size and decrease in cellularity. At birth, the tibial ligament inserted onto the thin cortical bone of the metaphysis via periosteum. At day 8, osteoclasts started to resorb the thin cortical bone at the ligament insertion, thus forming a metaphyseal depression between days 10 and 20. From days 20 to 120, the insertion remained qualitatively unchanged, showing three zones, the ligament, periosteum, and metaphyseal trabecular bone. The deep periosteal layer showed osteoclastic activity in the proximal part and osteoblastic activity in the distal part. The migration mechanism of the ligament insertion during growth seems to be caused by this growth-related osteoclastic resorption of the proximal metaphyseal bone and by simultaneous osteogenic activity, which successively cements the distal part of the ligament to bone. The persistence of the periosteal layer and the metaphyseal depression for up to 120 days may be regarded as a sign of continuing growth in this animal model. This is the first investigation showing that the formation of the metaphyseal depression is a purely postnatal event, and suggests that this process might be initiated by the change in mode of growth and joint biomechanics after birth, enabling ligament development and migration in a growing and increasingly loaded weight-bearing joint. The mainly resorptive process, which takes place during development of the tibial MCL insertion, may account for the tensile failure of this ligament that commonly occurs at this site during growth. The pronounced morphological differences between the chondral femoral and the periosteal tibial attachment of the adult MCL are apparently caused by the different postnatal developmental processes at epiphyses and metaphyses.Presented in part at the meeting of the Orthopaedic Research Society, Orlando, Florida, 13–16 February, 1995     

An initial qualitative study of dual-energy CT in the knee ligaments

OBJECTIVE: To study the clinical application of dual-energy CT (DECT) in the knee ligaments. METHODS: Twelve cases (24 knees) were scanned using dual-energy CT for the knee. Two- and three-dimensional images were used for display in all cases by means of multi-planar reformation (MPR) and volume rendering technique (VRT). All images were ranked by two radiologists according to the grade of knee ligament displayed, the definition of edge and attachment points of the knee ligament. RESULTS: The partial ligaments of 24 knees, such as the patellar ligament, fibular collateral ligament, anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were clearly displayed; the tibial collateral ligament was not satisfactorily displayed. The transversal ligaments, such as lateral patellar retinaculum and medial patellar retinaculum, and the posterior ligament, such as oblique popliteal ligament could not be shown clearly. CONCLUSION: The dual-energy CT is a new and valuable tool to qualitatively display the main ligaments of the knee.     

专用四肢关节低场MR在踝关节韧带急性损伤中的应用

目的评价专用四肢关节低场MR在踝关节韧带急性损伤中的应用价值。方法回顾分析23例踝关节急性创伤患者韧带和骨质损伤的MR表现。结果23例踝关节损伤包括外侧副韧带损伤15例、内侧副韧带损伤3例和内外侧副韧带共同受累5例,其中伴7例骨挫伤、4例骨折及10例踝骨关节炎。MR检查能全面直观显示多条韧带、骨和软骨结构损伤的范围程度。结论专用四肢关节低场MR在踝关节韧带损伤方面具有良好的应用价值,能全面评价踝关节损伤,为临床治疗提供依据。     

3．OTMRI 3D扫描对膝横韧带的观察

目的研究3．OTMRI3D扫描对膝横韧带的显示价值。方法回顾性分析利用3．0TMRI进行膝关节3D扫描的137例患者资料,共152个膝关节．除外严重外伤、肿瘤、关节感染及大量关节积液患者,共90人、100个膝关节纳入研究,平均年龄42岁．男性42位,女性48位。通过横断面及曲面重建观察并测算膝横韧带的出现率、长度、宽度、N-L分型、并测量其后缘与前交叉韧带胫骨附着点前缘的距离。结果共观察到膝横韧带54例,出现率54％;平均长度36．99mm（范围18．8-48．8mm）,平均宽度1．4mm（范围约0．80-2．53 mm）,N-L分型中,Ⅰ型、Ⅱ型、Ⅲ型所占比例分别为59．3％、25．9％、14．8％;其后缘与前交叉韧带胫骨附着点前缘的距离5．25mm（范围1．4-8．6mm）。结论3.0T MRI 3D扫描可从不同方位显示膝横韧带并对其解剖特点进行细致观察。     

The anterior intermeniscal ligament of the knee: an anatomic and MR study

Background  The purposes of this study were to identify the presence of the anterior intermeniscal ligament of the knee (AIL), to study its attachment patterns and relationships to other anatomic structures within the knee and to evaluate the potential association of its rupture with other pathology of the knee. Methods  Ten human cadaver knees were dissected excluding knees with surgical scars. Fifty-one MR examinations were performed in symptomatic patients. Arthroscopic observations were carried out on ten patients. Results  AIL was found in nine dissected knees with type I insertion in six cases, type II insertion in three cases. The average length was 31.2 mm (25–45 mm). The average distance between AIL and insertion of the anterior cruciate ligament was 12 mm (11–15 mm). Concerning MR study, AIL was found in 34 cases (82.9%). Four (9.75%) ruptures of the AIL were encountered. Where AIL was intact, 14 patients presented meniscal lesions (46.6%). Where AIL was ruptured, three patients presented meniscal lesions (75%). Conclusion  The present study demonstrates through anatomical and MR studies that AIL is present in more than 80% of the cases with predominant type I insertion. The association of meniscal and AIL lesions was highlighted demonstrating that AIL is not only an anatomical point of interest but also a clinical and surgical reality.     

Sonoelastography of the knee joint

Magnetic resonance imaging (MRI) is generally the preferred method for assessing lesions of the knee cartilage and subchondral bone. There have been a few cartilage imaging studies using real‐time elastosonography (RTE), which has increased in importance and range of use in recent years. The aim of this cadaveric study was to assess the efficacy of a new diagnostic method combining USG and RTE and also to perform intra‐articular examinations together with arthroscopy. A total of 12 fresh unpaired human knees were examined. The laparoscopic ultrasound transducer was deployed using standard anteromedial and anterolateral arthroscopic portals. Iatrogenic defects were examined using mosaicplasty tools in healthy‐looking areas of cartilage, and strain in those areas was measured using RTE. The median strain value of the pathological femoral cartilage region was significantly higher than that of the normal cartilage region (1.23 [0.71–2.24] vs. 0.01 [0.01–0.01], P = 0.002, respectively). Arthroscopic study of cartilage using RTE can be a guide for orthopedic surgeons and use of intra‐articular probes could be universalized. Clin. Anat. 32:99–104, 2019. © 2018 Wiley Periodicals, Inc.     

膝关节横断面解剖及临床意义

目的：明确膝关节横断面的解剖学特点，探讨其临床应用价值。方法：用火棉胶包埋技术对4侧成人尸体膝部进行水平位1～2mm厚的连续切片，观察膝部各结构在断面上的形态、位置和毗邻关系。结果：详细描述了膝部各结构的横断面表现。结论：膝关节横断面可较好显示膝部结构的位置关系，对膝关节疾病的影像学诊断具有重要价值。     

Anatomic bases of a vascularized allogenic knee joint transplantation: arterial blood supply of the human knee joint

Summary The vitality of a graft in a vascularized allogenic knee joint transplantation in humans will depend strongly on maintaining the arterial blood supply to the bone. As can be demonstrated in injected specimens on cadavers, only periostal aa. are important to ensure the blood supply of the human knee joint. The main arteries have defined nutritive areas. According to our results access to the vessels should most probably be conducted from the dorsal side of the knee. During the explantation the popliteal a. should be ligated proximally as high up as possible and distally just above its trifurcation. The articular branch of the descending genicular a. of both the donor and the recipient can be ligated because of a rich anastomotic network. The medial and lateral inferior genicular aa. of the donor should be ligated ventrally as far forward as possible. One should, above all, preserve the medial inferior genicular a. of the donor in order not to endanger the medial part of the distal segment of the graft. If an operation is to be performed according to the results of our anatomical studies, vascularized allogenic knee joint transplantations should be successful from an anatomical point of view.

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Bases anatomiques de la transplantation d'une allogreffe vascularisée de genou : vascularisation artérielle de l'articulation du genou humain

Résumé La vitalité d'une greffe lors d'une transplantation d'allogreffe vascularisée de genou dépendra principalement du maintien de la vascularisation artérielle de l'os. Comme on peut le montrer sur des spécimens cadavériques injectés, seules les artères périostées sont importantes pour assurer la vascularisation artérielle du genou humain. Les principales artères ont des territoires définis. En fonction de nos résultats, l'accès aux vaisseaux serait au mieux mené par le versant dorsal du genou. Pendant le prélèvement, l'a. poplitée devrait être sectionnée proximalement aussi haut que possible, et distalement juste au-dessus de sa trifurcation. Le rameau articulaire de l'a. descendante du genou du donneur et celui du receveur peuvent être liées en raison du riche réseau anastomotique. Les aa. géniculées inféro-médiale et inféro-latérale du donneur devraient être liées aussi loin que possible en avant. Il faudrait par dessus tout préserver l'artère géniculée inféromédiale du donneur pour éviter de léser la partie médiale du segment distal de la greffe. Si une transplantation d'un allogreffe vascularisée de genou devait être réalisée en tenant compte du résultat de nos travaux, elle devrait être un succès du point de vue anatomique.

     

延迟腓肠穿支带蒂皮瓣修复膝部软组织缺损

目的报告延迟腓肠内侧动脉穿支带蒂皮瓣修复膝部软组织缺损的临床应用结果。方法自2010年1月~2014年1月,应用延迟腓肠内侧动脉穿支带蒂皮瓣修复膝部软组织缺损6例(男5,女1)。患者年龄18~46岁,平均36岁。软组织缺损范围8.5cm×7.5cm~9cm×8cm。皮瓣切取范围9.5cm×9cm~10cm×9cm。皮瓣延迟时间:8~13天,平均11天。延迟期间创面暂时应用VSD覆盖。结果 1例皮瓣发生小的皮缘裂开,术后2周自然愈合,延迟皮瓣全部成活。术后随访2~4.5年(平均3.5年),受区与供区外形较好。膝关节功能用Baily提出的膝关节评分标准评定其疗效,良5例,可1例。本组取得了较满意的临床效果。结论该技术安全、可靠,适用于皮瓣切取较大或高风险患者。