The glenocapsular ligament and the posterosuperior part of the joint capsule of the shoulder are well vascularized

PURPOSE

A detailed structural anatomy of the posterosuperior shoulder capsule and "glenocapsular ligament" is still rather unknown. The purpose of this study was meticulously to investigate and describe the structure and blood supply of the glenocapsular ligament on the posterosuperior shoulder joint capsule.

METHOD

Sixteen fixed and twelve fresh cadaveric shoulder specimens with a mean age of 73.4 (±6.4) years were analysed. Dissection without arterial injection was performed on the 16 fixed specimens-using an alcohol-formalin-glycerol solution. Before dissection, the 12 fresh specimens received of arterial injection a 10% aqueous dispersion of latex solution. After the injection, these shoulders were also fixed in an alcohol-formalin-glycerol solution.

RESULTS

The glenocapsular ligament was found in all 28 specimens. Single or double parallel-running bundles of connective tissue fibres were found to form a capsular-ligamentous structure on the posterosuperior part of the joint capsule. One part of the ligament was mediosuperior, another posterosuperior. The mediosuperior part varied in shape, and in 12 of 28 cases, it was absent. The glenocapsular ligament arose from the supraglenoid tubercle and posterior part of the collum scapulae and inserted into the semicircular humeral ligament. The posterior ascending branch of the circumflex scapular artery directly fed small branches laterally and medially to the joint capsule, supplying the glenocapsular ligament and the deep layer of the joint capsule.

CONCLUSION

The glenocapsular ligament is a constant anatomical structure that consists of one or two different parts. The glenocapsular ligament and the posterosuperior part of the joint capsule appear well vascularized via the posterior ascending branch of the circumflex scapular artery.

CLINICAL RELEVANCE

It is the hope of the authors that this anatomical study can help surgeons who perform open or arthroscopic surgery to the posterior part of the shoulder. Knowledge of the vascular anatomy presented in this study may be especially important when incisions are made to the posterior part of the shoulder, and should minimize the risk of complications.

The variable morphology of suprascapular nerve and vessels at suprascapular notch: a proposal for classification and its potential clinical implications

PURPOSE

The most common place for suprascapular nerve entrapment is the suprascapular notch. The aim of the study was to determine the morphological variation of the location of the suprascapular nerve, artery and vein, and measure the reduction in size of the suprascapular opening in each type of the passage.

METHODS

A total of 106 human formalin-fixed cadaveric shoulders were included in the study. After dissection of the suprascapular region, the topography of the suprascapular nerve, artery and vein was evaluated. Additionally, the area of the suprascapular opening was measured using professional image analysis software.

RESULTS

Four arrangements of the suprascapular vein, artery and nerve were distinguished with regard to the superior transverse scapular ligament: type I (61.3 %) (suprascapular artery was running above ligament, while suprascapular vein and nerve below it), type II (17 %) (both vessels pass above ligament, while nerve passes under it), type III (12.3 %) (suprascapular vessels and nerve lie under ligament) and type IV (9.4 %), which comprises the other variants of these structures. Statistically significant differences regarding the suprascapular opening were observed between the specimens with types II and III. Anterior coracoscapular ligaments were present in 55 from 106 shoulders.

CONCLUSION

The morphological variations described in this study are necessary to better understand the possible anatomical conditions which may promote suprascapular nerve entrapment (especially type III). They may be useful during open and endoscopic procedures at the suprascapular notch to prevent such complications as unexpected bleeding.

Prominent Vascular Remnants in the Calcaneus Simulating a Lesion on MRI of the Ankle: Findings in 67 Patients with Cadaveric Correlation

OBJECTIVE

Our objective was to prove through cadaveric correlation that a frequently seen focus of MRI signal in the calcaneus is benign.

CONCLUSION

A characteristic focus of signal (increased T2, decreased T1) in the calcaneus near the attachment of the cervical and interosseous ligaments is a common, benign finding frequently seen on MRI of the foot and ankle.

Vascular adaptation of intact joint stabilizing structures in the posterior cruciate ligament deficient rabbit knee

Loss of the posterior cruciate ligament (PCL) of the knee has a significant impact on joint stability and biomechanical function. Changes in joint biomechanics may result in mal-adaptive tissue degeneration and functional alteration of supporting ligaments. This study examines the effects of joint laxity on the vascular physiology of the intact anterior cruciate (ACL) and medial collateral (MCL) ligaments after PCL transection in rabbits.One-year-old female New Zealand white rabbits were assigned to control (n=12), sham-operated (n=12) or PCL transected (2, 6 or 16 weeks, n=12 per time point) groups. Half of the animals (n=6 per group) were used for ACL and MCL blood flow determination using coloured microsphere infusion (ml/min/100 g), and half were used for vascular volume determination (given as vascular index, micro l/g). In the MCL, PCL transection induced large, significant (4-5-fold) increases in blood flow (peak at 2 weeks) and vascular index (peak at 6 weeks) compared to sham-operated animals that returned towards control values by 16 weeks. In contrast, the ACL showed no increase in blood flow in lax joints, and a relatively small (2-fold) increase in vascular index at 6 weeks only. The wet weight and water content of both the MCL and ACL were significantly increased in PCL-deficient joints. We conclude that joint laxity (instability) subsequent to loss of the PCL in rabbits impacts the vascular physiology of intact supporting ligaments, inducing both vasomotor and angiogenic responses in the MCL. Changes in wet weight and water content of both the MCL and ACL demonstrate prolonged physiological adaptation of intact structures in lax joints.

Revascularization of the artery of the ligamentum teres in Perthes disease

To study revascularization of the artery of the ligamentum teres in Perthes disease, superselective angiography was done in 22 hips. Normal appearance of the artery of the ligamentum teres was observed in two hips, both of which were of Catterall Group II in the healing stage. Thirteen hips of Catterall Group III or IV with collapse (initial stage in nine hips, fragmentation in two hips, healing in two hips) were free from apparent subluxation; however, their epiphyses were not vascularized to the medial margin. Seven hips with apparent subluxation of Catterall Group III or IV (fragmentation stage in three hips, healing in four hips) had extensive vascularized medial viable segments consisting of newly formed small arteries. Penetration of revascularization from the artery of the ligamentum teres was inhibited by collapse initially at the medial margin of the epiphysis. Revascularization consisted of newly formed small arteries that penetrated the medial area of the epiphysis after subluxation. After completion of healing, blood supply from the artery of the ligamentum teres was not important for nourishment of the capital femoral epiphysis. The authors conclude that normal vascular anatomy of the artery of the ligamentum teres is not related to the onset of Perthes disease.

Anatomy, histologic features, and vascularity of the adult acetabular labrum

Acetabular labrum tears have been implicated as a cause of hip pain in adult patients. Few studies describe the anatomy, histologic features, and microvasculature of the acetabular labrum and labral tears. Fifty-five embalmed and 12 fresh-frozen adult hips with a mean age of 78 years (range, 61-98 years) were studied. Of these, 96 % (53 of 55) of the hips had labral tears, with 74% of the tears located in the anterosuperior quadrant. Histologically, the fibrocartilaginous labrum was contiguous with the acetabular articular cartilage through a 1- to 2-mm zone of transition. A consistent projection of bone extends from the bony acetabulum into the substance of the labrum that is attached via a zone of calcified cartilage with a well-defined tidemark. Two distinct types of tears of the labrum were identified histologically. The first consisted of a detachment of the fibrocartilaginous labrum from the articular hyaline cartilage at the transition zone. The second consisted of one or more cleavage planes of variable depth within the substance of the labrum. Both types of labral tears were associated with increased microvessel formation seen within the tear. The acetabular labrum tear appears to be an acquired condition that is highly prevalent in aging adult hips. Labral tears occur early in the arthritic process of the hip and may be one of the causes of degenerative hip disease.

[Arterial supply of the femoral condyles]

INTRODUCTION

The most frequent site for aseptic bone necrosis and osteochondrosis dissecans in the human knee joint is the medial femoral condyle. The aim of this study is to analyze the three-dimensional vascularization of the human knee joint and to find out if there are any differences in the blood supply of the medial and lateral femoral condyles which may explain the preponderance of aseptic bone necrosis in the medial side.

MATERIAL AND METHODS

The femoral arteries of 14 unfixed lower extremities have been injected with epoxy resin. After documentation of the extraosseous course of the blood vessels the bone was macerated with 10% formic acid. The insertions of tendons and ligaments were investigated by light microscopy and immunohistochemistry.

RESULTS

The arterial supply of the lateral femoral condyle originates from the upper lateral geniculate artery, the terminal ends of which penetrate the bone from lateral. Branches of the middle geniculate artery reach the bone from the medial wall of the intertubercular notch. The subchondral bone of the medial femoral condyle draws its blood supply mainly from the descending geniculate artery. Branches of the middle geniculate artery penetrate the medial femoral condyle only in the posterior part of the intercondylar fossa. These posterior vessels do not contribute to the supply of the subchondral bone. In the anterior part of the medial wall of the intercondylar fossa there is the wide femoral insertion of the posterior cruciate ligament. Injection techniques and immunohistochemical investigations show that the fibrocartilage of the chondral apophyseal insertion of the posterior cruciate ligament is avascular and acts as banier which impedes blood vessels to penetrate the bony surface in this region. The subchondral bone adjacent to the femoral insertion of the posterior cruciate ligament receives its blood supply from vessels that penetrate the bone at the medial wall of the medial femoral condyle. The blood vessels which supply the lateral parts of the medial condyle have the longest intraosseous course. The density of vessels within this region is largely reduced.

CONCLUSIONS

The region adjacent to the femoral insertion of the posterior cruciate ligament is the most frequent site for osteochondrosis dissecans in the knee joint. Our results show that the arterial supply of the subchondral bone may be considered as a cofactor for the etiology of osteochondrosis dissecans.

The intercruciate band of the human knee. An anatomical and histological study

Thirty cruciate ligaments were retrieved from either cadavers or limbs which had been amputated. Each specimen was sectioned and stained to demonstrate the presence of collagen, nerves and vessels. All 30 specimens contained an interconnecting band of collagen fibres between the anterior and posterior cruciate ligaments. Vascular structures were present in all specimens and nerve fibres were identified in 26 (86%). We have called this structure the 'intercruciate band'. The anterior and posterior cruciate ligaments should no longer be thought of in isolation, but together as a 'cruciate complex'.

Anatomical study of the blood supply in the human shoulder region

The blood supply of the shoulder muscles, ligaments and joint capsule was investigated by injection of silicone rubber into the arteria subclavia of postmortem cases. We show that the a. suprascapularis forms important anatomoses with other arteries in the region and is of greater importance for the blood supply of the rotator cuff as hitherto believed. We also describe the a. subcoracoidea as a so far unknown branch of the a. axillaris.

In vivo comparison of scanning technique and wavelength in laser Doppler perfusion imaging: measurement in knee ligaments of adult rabbits

At present, there are only two laser Doppler perfusion imaging systems (LDIs) manufactured for medical applications: a 'stepwise' and a 'continuous' scanning LDI. The stepwise scanning LDI has previously been investigated and compared with coloured microsphere determined standardised flow. The continuous scanning LDI is investigated and compared with the stepwise scanning LDI for its ability to measure in vivo, hypoaemic, ligament tissue blood flow changes. The continuous scanning system was supplied with two lasers, red and near infrared (NIR), allowing for additional assessment of the effect of wavelength on imaging ligament perfusion. Perfusion images were obtained from surgically exposed rabbit medial collateral ligaments (MCL). Continuous and stepwise LDI scans were compared using correlation and linear regression analysis of image. averages and standard deviations. Using the same method of analysis, LDI measurements using red and NIR lasers indicated a high degree of correlation, at least over the ranges of perfusion assessed, indicating that red and NIR lasers measure similar regions of flow in the rabbit MCL. These experiments confirm that both LDI techniques provide a valid in vivo measure of dynamic changes in connective tissue perfusion and could have significant impact on the understanding and treatment of joint injury and arthritis.

Evaluation of laser Doppler imaging to measure blood flow in knee ligaments of adult rabbits

Laser Doppler imaging (LDI) is investigated as a novel method for in vivo ligament tissue blood flow determination. LDI output signal is obtained from surgically exposed rabbit medial collateral ligaments (MCL). The LDI signal is compared with simultaneously determined, coloured microsphere (CM)-derived standardised MCL blood flow. Correlation of LDI output with the CM flow data and a linear regression of 17 data points in nine rabbits (joint injured to provoke an acute vascular response in the tissues) indicate that LDI provides a reasonable estimate of MCL blood flow, at least over the ranges assessed. If properly calibrated, and given enough tissue-specific data points, LDI may have advantages over conventional, but more invasive, techniques. The potential clinical application of LDI technology to joint injury and arthritis research is discussed.

Gross, histological, and microvascular anatomy and biomechanical testing of the spring ligament complex

In recent years there has been an increased interest in the treatment of acquired pes planus. The breakdown of the medial longitudinal arch is most often seen at the talonaviculocalcaneal articulation. This suggests a relationship between the ligamentous complex at this articulation and acquired pes planus. This study was undertaken to gain a better understanding of the gross, histologic, and microvascular anatomy, as well as the biomechanics of the ligamentous structures surrounding the talonaviculocalcaneal articulation. Cadaver dissections of 38 fresh-frozen feet were performed. Detailed descriptions of the gross anatomy of the superomedial calcaneonavicular ligament, inferior calcaneonavicular ligament, and the superficial deltoid ligament were recorded. Their relationships to the posterior tibialis tendon and to the bones of the talonaviculocalcaneal articulation are described. The histology and microvascularity of these structures were also studied. Preliminary biomechanical testing was performed. It was found there are two definitive anatomic structures that are commonly called the spring ligament: the superomedial calcaneonavicular ligament (SMCN) and the inferior calcaneonavicular ligament (ICN). The SMCN ligament was found to have histologic properties that suggest significant load bearing. The histology of the ICN ligament suggests a pure tensile load function. The deltoid ligament and the posterior tibialis tendon had direct attachments to the SMCN ligament in all specimens. An articular facet composed of fibrocartilage was found in each SMCN ligament specimen. The microvascular structures showed an avascular articular facet present in the ligament. The biomechanical testing showed that the SMCN ligament and ICN ligament had strength similar to ankle ligaments. This study suggests this "spring ligament complex" has more of a "sling" function for the talar head. It is hoped that the better understanding of this region will add to our understanding of the etiology of pes planus and possible treatment alternatives.

[An experimental study on tissue induction in anterior cruciate ligament reconstruction with the scaffold-type polyester artificial ligament (Leeds-Keio)]

The effect of experimental autogenous tissue implantation (infrapatellar fat pad, fascia lata) together with scaffold type artificial ligament (Leeds-Keio) in ACL reconstruction was studied in 56 mongrel adult dogs. Specimens were examined macroscopically, histologically and by means of microangiography. The results were compared with those in which the artificial ligament was used alone. When infrapatellar fat pad was transferred on artificial ligament, tissue induction was observed 2 weeks after reconstruction. When ACL was reconstructed using a combination of artificial ligament and a small piece of fascia lata, maturated dense collagen fibers were observed 24 weeks after reconstruction. These results indicated that quicker tissue induction could be obtained in ACL reconstruction using an artificial ligament together with a infrapatellar fat pad, and that collagen fiber maturation was accelerated when ACL was reconstructed using an artificial ligament together with a small piece of fascia lata.

Quantitative analysis of the fine vascular anatomy of articular ligaments

An image analysis technique has been developed to quantitatively describe the fine vascular patterns observed in ligament tissue. The longitudinal orientational distribution and total vessel volume of India-ink-perfused blood vessel segments in normal and healing ligaments were determined. The methods involved special vascular preparation of adult rabbit knee medial collateral ligaments (MCL) by India-ink perfusion. Black and white microscope images of ink-perfused tissue sections were subjected to a thresholding procedure to binarize digitized ligament images, which were then skeletonized and analyzed for directional distribution based on the least-squares technique. Analysis of medial collateral ligaments in New Zealand White rabbits using this method has shown that scarred tissue is more vascular and has a more chaotic angular distribution of blood-vessel segments than normal ligament tissue.

Anterior cruciate ligament allograft transplantation for intraarticular ligamentous reconstruction

A multiplicity of surgical operations have been developed in an attempt to achieve satisfactory function after anterior cruciate ligament (ACL) repair. None of these procedures have been able to reproduce the fiber organization anatomy of attachment site, vascularity, or function of the ACL. Twenty-nine foxhounds received a deep-frozen bone-ACL-bone allograft and a ligament augmentation device (LAD). Biomechanical, microvascular, and histological changes were evaluated 3, 6, and 12 months following implantation. The maximum loads of the allograft/LADs were 34.3% (387.2 N) after 3 months, 49.3% (556.6 N) after 6 months, and 61.1% (698.8 N) after a year. The maximum load was 69.1% (780 N). In general, after 6 months the allografts showed normal collagen orientation. The allografts demonstrated no evidence of infection or immune reaction. No bone ingrowth into the LAD was observed. Polarized light microscopy and periodic acid-schiff staining showed that the new bone-ligament substance interface had intact fiber orientation at the area of the ligament insertion. Microvascular examination using the Spalteholtz technique revealed revascularization and the importance of an infrapatellar fat pad for the nourishment of ACL allografts.

Vascular assessment of the periarticular ligaments of the rabbit knee

While the rabbit is being extensively utilized in animal models for orthopaedic research, the vascular anatomy of the knee ligaments has not been thoroughly described in this species. This study demonstrates the blood supply to the infrapatellar fat pad, the cruciate ligaments, the medial collateral ligament (MCL), and the menisci, such that the effects of manipulating these tissues may be properly interpreted. Vascular injection with India ink and iodinated i.v. contrast dye was performed in 11 New Zealand white rabbits, and routine histology done on six. The large vessel anatomy is similar to that described for humans and dogs, with a descending geniculate artery, medial and lateral superior and inferior geniculate arteries, a posterior geniculate artery, and a recurrent anterior tibial artery. The microvascular anatomy is also similar in that the infrapatellar fat pad and synovial membrane are highly vascular, the menisci are vascularized from their periphery (being avascular centrally), and the medial collateral ligament is relatively well vascularized. A difference from dogs and humans is present in the anterior cruciate ligament (ACL), which is poorly vascularized, with a single artery on its anterior aspect. High magnification histologic evaluation reveals numerous capillaries in the substance of the MCL, while the ACL is nearly devoid of such vessels. The interspecies variation in vascular anatomy is a variable that must be taken into consideration in any surgical or traumatic animal model investigation of knee pathology.

[Development of the ligamentum capitis femoris and the artery with the same name]

A morphological study concerning the development of the ligamentum teres and its artery was performed by investigating 300-600 microns thick epoxy resin impregnated sections through the hip joints of human fetuses and newborn children. In addition, the hip joints were macroscopically studied in three fetuses and in two newborn children. After photographical documentation the ligamenta teretes of these hips were processed into paraffin section. Within the ligamentum teres areas of different structures can clearly be distinguished during fetal development. The subsynovial layer consists of dense connective tissue containing numerous large cells. The major central portion of the ligament is formed by dense regular connective tissue. The blood vessels of the ligament are always surrounded by a layer of loose connective tissue. Adipose tissue firstly starts to spread in the postnatal period mainly occurring around the vessels. In the newborn child dense connective tissue is most abundant within the ligamentum teres. Thus it is considered to be especially strong. The femoral capitis artery is already present in 9 week-old fetuses. In 13 week-old fetuses branches of the femoral capitis artery enter the femoral head through cartilaginous channels and continuously maintain within the femoral head during further development. With the growing age of the fetuses the number of branches of the femoral capitis artery increases. Anastomoses between the cartilaginous channels of the femoral capitis artery and the medial and lateral circumflexal femoral artery can be found neither prenatally nor postnatally.

Histologic anatomy of the triangular fibrocartilage

Histologic examination of the TFC reveals parallel, longitudinally oriented collagen fibers peripherally, while the more central articular disc is made up of interweaving obliquely oriented sheets of collagen fibers. This suggests a peripheral region experiencing tensile loads between the region of origin from the radius and the area of insertion into the ulna. The fiber orientation in the central region is more compatible with a structure experiencing multidirectional stresses. The articular disc origin from the radius is reinforced by collagen bundles projecting out from the radius for 1 to 2 mm. A large number of traumatic tears are oriented parallel to the radial origin of the TFC and located approximately 1 to 2 mm from the origin site. This corresponds to the junction of the short, radially oriented fibers and the remainder of the articular disc. The inner 80% of the articular disc is avascular, as is its radial attachment. Traumatic tears in this region would have a low healing potential unless some method for introducing additional vascularity was undertaken, such as reattachment through drill holes in the radius, allowing neovascularization of this otherwise avascular region.

Healing of ligaments in synovial fluid. An experimental study in rabbits

To investigate the importance of nutritive environment in the healing of reconstructed ligaments, the morphology of sutured free patellar ligaments in synovial fluid of the contralateral knee joint, without re-establishment of microcirculation, was studied in rabbits. After two weeks (n = 6) and one (n = 6) and three (n = 5) months, the sutured ligament was removed from the joint and fibroblasts were seen growing into the suture gap. The ligaments were enveloped in a capsule of fibroblasts, which was more developed in those ligaments that were studied three months after operation. The collagen of the piece of ligament was disorganised at all time points, and tensile strength (n = 6) was low compared with non-sutured patellar ligament. Some ligaments disappeared or were partly attached to the synovial membrane and revascularised. The findings indicate that diffusion of nutrients may be important for the survival and healing of reconstructed ligaments, as the ligaments can heal in synovial fluid without re-establishment of the microcirculation.

Fine vascular anatomy of adult rabbit knee ligaments

The microvascular anatomy of discrete knee ligaments in adult rabbits is described. Epiligamentous plexuses give rise to a limited number of vessels which penetrate deeply into ligament substance. Intraligamentous vessels are usually longitudinally orientated, widely separated linear anastomoses but occasionally complex glomus-like configurations are present. The significance of these findings is discussed in relation to other articular connective tissues and to the possible roles of the intraligamentous microvasculature.

Rationale and protocol for postoperative anterior cruciate ligament rehabilitation

A rehabilitation program for postoperative anterior cruciate ligament (ACL) reconstruction permits adequate tissue healing time and allows early protected muscular conditioning. The program is based on kinematic, biomechanical, and kinesiologic factors as they pertain to ACL function. The program is divided into five phases. The early phases, zero to 12 weeks, are intended to control translational forces across the ACL and to allow necessary time for ligament revascularization and soft-tissue healing. During this period, isometric and isotonic training of the hamstrings and quadriceps muscle groups in a restricted active arc of motion is permitted. Passive motion is encouraged, and progressive weight bearing is allowed. Conditioning of the upper body as well as the nonsurgical lower limb is stressed. During the advanced phases, 12-31 weeks, isotonic muscle training continues throughout a full range of motion. Greater strength, coordination, and endurance to achieve dynamic stability of the knee, preparing the patient for unrestricted activity, are stressed. Approximately 52 weeks of active rehabilitation after ACL reconstruction surgery are usually required to return to a preinjury level of function.

Effects of exercise on blood flow to canine articular tissues

We measured articular blood flow by standard microsphere techniques in normal adult dogs at rest and during treadmill exercise. All animals but one underwent beta-adrenergic blockade as part of another experimental protocol. Expressed in microliter/min/g +/- SEM, baseline flow values to articular tissues were: knee synovium 26 +/- 4, femoral condyle 130 +/- 21, tibial plateau 182 +/- 29, articular fat pad 9 +/- 2, knee ligaments 17 +/- 3, menisci 34 +/- 6, wrist synovium 19 +/- 4, distal radius 65 +/- 13, and lunate bone 59 +/- 13. Blood flow increased with exercise in all soft tissues of both the knee (stifle joint) and the wrist (radiocarpal joint). Geometric mean exercise/rest flow ratios ranged from a low of 1.44 (p less than 0.05) in the menisci of the knee to a high of 7.25 (p less than 0.001) in the synovium of the wrist. In contrast, blood flow did not rise in juxtaarticular bones and fell significantly in femoral condyles (mean flow ration 0.71, p less than 0.005). These findings indicate that articular soft tissues derive increased perfusion from the redistribution of blood flow that accompanies short-term exercise. In contrast, flow to juxtaarticular bone does not increase under these conditions.

Microvascular anatomy of the radioscapholunate ligament of the wrist

The microvascular circulation and basic structural features of the radioscapholunate ligament of the wrist were studied in six fresh cadaver specimens by injection and clearing techniques. A rich vascular supply was found to originate from vessels that perforate the palmar capsule and enter the synovium that surrounds the ligament. By way of branches from the synovium, the radioscapholunate ligament and most of the scapholunate interosseous ligament receive an abundant blood supply. No contributions are derived from the bony attachments. Observation under light microscopy revealed a delicate, well-vascularized ligament consisting of regular collagen bundles. No elastic fibers were observed. This study indicates that the radioscapholunate ligament has a vascular supply that may be sufficient for healing by known methods.

Quantification of the perfusion of the anterior cruciate ligament and the effects of stress and injury to supporting structures

The perfusion of the normal ACL was quantitated using the hydrogen washout technique in a canine model. This was compared to the perfusion of the synovium in the suprapatellar pouch. Changes in the ACL perfusion were quantitated after the application of anterior stress, division of the infrapatellar fat pad, and dissection of the synovium enveloping the ACL. The ACL is relatively hypovascular, with one-half the blood flow of the synovium of the suprapatellar pouch. Application of an anterior stress diminishes the blood flow to the ACL to one-fifth of the baseline value, an effect which is reversible. Division of the infrapatellar fat pad causes a two-fold decrease in perfusion to the ACL, whereas dissection of the enveloping synovium results in a complete cessation of blood flow.

The anatomy of the extensor mechanism

The complex function of the extensor mechanism demands knowledge of not only its anatomic structures but of their balanced relationships as well. An awareness of a layer concept of tissue orientation is helpful in understanding surgical access as well as the normal function of the decelerator mechanism. This awareness is a prerequisite to the evaluation and treatment of mechanical disorders.

Early histologic, metabolic, and vascular assessment of anterior cruciate ligament autografts

A rabbit model for anterior cruciate ligament (ACL) reconstruction using autogenous patellar tendon was utilized to study the early events of autograft cellular dynamics. Biochemical, autoradiographic, histological, and vascular injection techniques demonstrated that the native autograft cell population rapidly necroses. This repopulation occurs without a vascular contribution; cells entering the autograft are reliant upon synovial fluid nutrition.

Maturation of autogenous tendon grafts in anterior cruciate ligament reconstruction of the human knee--an arthroscopic study

Fifty-six arthroscopic observations on 53 knees at various intervals after anterior cruciate ligament (ACL) reconstruction using the autogenous quadriceps and patellar tendon were analyzed to clarify the morphological maturation process of the grafts in human patients. Arthroscopic observations of the grafts were divided into four types, except for one rerupture case. In type I, thick synovial tissue with abundant capillary blood vessels filled the intercondylar fossa. In type II, synovial tissue mass was decreased and ligamentous tissue showed through the thin synovial tissue. In type III, relatively thick synovial tissue with many folds and abundant capillary blood vessels enveloped thick ligamentous tissue. In type IV, thin synovial tissue with relatively few blood vessels enveloped thick ligamentous tissue. Correlation between these graded types and intervals after reconstruction was significant (chi-square test, p less than 0.001). These four types of arthroscopic findings are thought to represent four phases of the maturation process of autogenous grafts after ACL reconstruction in human patients.

The Blood Supply of the Flexor Retinaculum

The anatomical details of the vascularization of the flexor retinaculum of the hand have been studied. The principal sources of blood supply were revealed by means of coloured latex injection and trans-clarification by the Spalteholz method. Micro-dissection demonstrated the existence of two networks, superficial and deep; the superficial network is formed by branches of the ulnar artery and the deep network by branches of the palmar superficial arch. These observations could have practical significance with regard to the site of incision in carpal tunnel operations.

Cruciate reconstruction using freeze dried anterior cruciate ligament allograft and a ligament augmentation device (LAD). An experimental study in a goat model

One ACL in each of 11 mature goats was replaced with a freeze dried bone-ACL-bone allograft and a ligament augmentation device (LAD). The LAD was released from its tibial fixation at 3 months postoperation. Biomechanical, microvascular, and histological changes were evaluated 1 year following implantation. The reconstructed knees had a significantly greater total AP translation (3.1 +/- 0.5 mm) (mean and SEM) than the contralateral controls (1.0 +/- 0.1 mm). Differences in primary AP translation were responsible for 59% of the difference in total translation, with only a 0.6 mm difference in secondary translation. Neutral stiffness in the reconstructive knee was 22% of control, while stiffness at 30 N of anterior force was approximately 35% of controls. Ligament stiffness in the linear region for the ACL allograft/LAD was 53% of the control value of 691 N/mm. The maximum load of the allograft/LADs was 1,052 +/- 145 N, or 43% of the contralateral ACL control strength (2,448 +/- 144 N). Five of the six allografts failed at the femoral insertion. Energy (39%) to maximum load was less for allograft/LADs than controls but elongation to maximum load was the same as control. Histologic evaluation of the allograft/LADs revealed soft tissue cellular ingrowth into the LAD in the extraarticular portions. No bony growth into the LAD was observed. The collagen fibers of the graft appear to be arranged in a longitudinal orientation although some areas show chaotic collagen fibers. Microangiography revealed a periligamentous and endoligamentous vascular pattern reminiscent of a normal ACL and complete revascularization of the bone plugs.

Atherosclerosis of the vessels in the ligamentum teres. Optical and electron microscopy findings in elderly patients with femoral neck fractures

The ligamentum teres was studied in 20 subjects, aged from 64 to 83 years, with fractures of the femoral neck treated by prosthetic replacement during 1985. The arterioles were examined under a stereoscopic dissection microscope; they were further studied by optical and electron microscopy. Almost complete occlusion by typical proliferative atherosclerotic changes was a constant finding, thereby cutting off any significant vascular supply to the femoral head.

Graft tension in anterior cruciate ligament reconstruction. An in vivo study in dogs

The purpose of this study was to examine the effect of initial tensioning on the outcome of reconstruction of the ACL. The ACLs of 15 adult mongrel dogs were excised and reconstructed. In the first five dogs, the ACLs of both knees were reconstructed using the medial one-third of the patellar tendon. The graft was fixed under a tension of 1 N (0.22 pounds) in one knee and 39 N (8.8 pounds) in the opposite knee. In the remainder of the dogs, the reconstructions were augmented with Dacron prostheses. Tensioning of both graft components in the augmented reconstructions was either with 1 N in one knee and 39 N in the contralateral knee or disproportionate tensions of 1 N and 39 N applied to the autogenous material and to the prosthesis. Sacrifice was 3 months postsurgery and results were examined with microangiography/history and mechanical testing. In the reconstructions with the patellar tendon alone, the biologic study showed poor vascularity and focal myxoid degeneration within the graft pretensioned with a load of 39 N. In the augmented reconstructions, the knees in which both graft materials were fixed with 1 N tension showed the strongest and stiffest reconstruction at 3 months. The study suggests that minimal tension should be applied to the graft materials during surgical reconstruction of the ACL.

The use of laser Doppler flowmetry to evaluate anterior cruciate blood flow

The purpose of this study was to quantitate the blood flow of the anterior cruciate ligament in vivo. Functional flow was evaluated using laser Doppler flowmetry (LDF), for which the output signal, blood cell flux (BCF), is expressed in terms of volts. Ten patients undergoing routine arthroscopic surgery with clinically intact anterior cruciate ligaments were selected at random for participation in the study. Under arthroscopic visualization, a 2.2-mm probe was placed through a trocar sleeve into the anterior cruciate ligament after the arthroscopic procedure. Pulsatile flow within the ligament was observed in all patients. The mean maximum BCF value ranged from 101 to 274 mV; SD range was +/- 3-9 mV. The mean minimum BCF ranged from 75 to 197 mV; SD range was +/- 0 to 9 mV. Laser Doppler flowmetry offers significant promise as a method for measurement of in vivo anterior cruciate and cruciate substitution blood flow.

Anterior cruciate ligament allograft transplantation. Long-term function, histology, revascularization, and operative technique

In recent years much effort has been devoted to finding a satisfactory replacement for the injured ACL. None of the reconstruction techniques used in the past can be considered ideal because of their inability to duplicate the complex geometry, structure, and function of the ligament. Current advances in allograft transplantation and cryopreservation have led us to design and implement an experimental model for testing the feasibility of cryopreserved ACL allotransplantation. Groups of dogs were used to evaluate the effect of cryopreservation on ligament strength and to compare the relative performance of both autograft and allograft ACL transplants up to 18 months after implantation. The ligaments were examined mechanically, histologically, and microangiographically. The cryopreservation process and duration of storage had no effect on the biomechanical or structural properties of the ligament. The mechanical integrity of the allografts was similar to that of the autografts, with both achieving nearly 90% of control ligament strength by 36 weeks. Revascularization approached normal by 24 weeks in both autograft and allograft. No evidence of structural degradation or immunological reaction was seen. Based on these results, we believe that a cryopreserved ACL allograft can provide the ideal material for ACL reconstruction. We have outlined a surgical technique for harvesting and implanting this graft clinically.

[Effect of the Hoffa fat pad on revascularization of the ruptured anterior cruciate ligament. A histologic study of the rabbit model]

After intersection of anterior cruciate ligament both ends were stitched together again. In group A the ligament was surrounded by a flap of fat pad, whereas in control group B the intersected ligament just was sutured. Postoperative the leg was immobilised by cast from 4 to 8 weeks. After that time intraarterial injection by Romeis method was performed, the bone-ligament-bone block was fixed in paraffine and the histological investigation followed. All ligament blocks of group A (n12) showed an intact anterior cruciate surrounded by well vascularized soft tissue which has been transformed from the fat pad. Ligaments of group B did not heal and where regressive changed.

Blood supply to the anterior cruciate ligament and supporting structures

The blood supply to the knee arises from a vascular plexus that surrounds the joint. The descending genicular artery, the medial and lateral inferior genicular arteries, the medial and lateral superior genicular arteries, the middle genicular artery, and the anterior and posterior tibial recurrent arteries contribute vessels that supply the various structures of the knee. The intra-articular soft tissues of the knee (the infrapatellar fat pad and synovium) mediate the blood supply to the cruciate ligaments, and preservation and utilization of these tissues should be considered when repair or reconstruction of the anterior cruciate ligament is being performed.

Replacement of the anterior cruciate ligament by an allogeneic tendon graft. An experimental study in the dog

The revascularisation and remodelling of allografts used to replace the anterior cruciate ligament in the canine knee were studied by microangiographic, histological and biomechanical methods. The 26 allografts were obtained from the patellar tendons of other dogs and were stored by deep freezing. In a control study a strip of patellar tendon from the same leg was used as an autologous free graft. Microangiography showed that the allografts had been revascularised from the sixth postoperative week, and had later developed an intrinsic vascular pattern similar to that of a normal anterior cruciate ligament. Histologically, the allograft regained a fibrous framework similar to that of a normal ligament, and showed no evidence of immunological rejection. Biomechanical tests on the allograft replacements showed that their mean maximum tensile strength at 30 weeks was about 30% of that of the control ligaments. There were no significant differences between the mechanical properties of the allografts and the autografts.

Anatomy of the anterior cruciate ligament

The anterior cruciate ligament (ACL) is a multifascicular structure whose femoral and tibial attachments, as well as spatial orientation within the knee, are directly related to its function as a constraint of joint motion. The ACL is made up of multiple collagen bundles that give rise to the multifascicular nature of the ligament. This arrangement results in a different portion of the ligament being taut and therefore functional, throughout the range of motion. The ACL receives its blood supply from branches of the middle genicular artery, which from a vascular synovial envelope around the ligament. These periligamentous vessels penetrate the ligament transversely and anastomose with a longitudinal network of endoligamentous vessels. The body attachments do not contribute significantly to the vascularity of the ligament. The nerve supply to the ACL originates from the tibial nerve. Although the majority of fibers appear to have a vasomotor function, some fibers may serve a proprioceptive or sensory function.

Form and function of radioulnar articular disc

1. The human radioulnar articular disc is a shelf extended medially from articular cartilage on carpal facet of radius. 2. Its medial border is embedded in the wedge of vascular connective tissue which contains fine arcuate ligamentous bands joining the disc to the ulna and articular capsule. 3. The ventral and dorsal borders are loosely attached to short ligaments which go from radius to the inner surface of articular capsule. 4. These arrangements permit radius and disc to rotate on ulna freely during pronation and supination.

Anterior and posterior cruciate ligament reconstruction in rhesus monkeys

Although numerous procedures have been described for the reconstruction of the anterior and posterior cruciate ligaments, there has been little evaluation of the viability and strength of these substitutes. Using microangiographic, histological, and biomechanical techniques, we studied the vascularity and tensile strength of the medial one-third of the patellar tendon at intervals after it had been inserted as a substitute for either the anterior or the posterior cruciate ligament in twenty-nine young adult Rhesus monkeys. For the anterior cruciate reconstruction (nineteen knees), we used and medial one-third of the patellar tendon elongated by a portion of the patella. For the posterior cruciate reconstruction (ten knees), we used the medial one-third of the patellar tendon lengthened by attached portions of the patella and tibia as a free graft. Both the anterior and the posterior cruciate ligament substitutes were revascularized at eight weeks, and at one year they had approximately 80 per cent of the tensile strength that they had prior to transfer.

[Angioarchitectonics of the costovertebral joints of embryos, fetuses, and newborn infants]

Blood supply of the costo-vertebral joints has been studied in human embryos (18), fetuses of various age (83) and newborns (4). Methods of preparation, circulatory bed injection with various contrasting masses--for roentgenography and Indian ink with gelatin suspension--for microscopic investigations have been applied. Histological sections (both sagittal and horizontal) have been stained after van Gieson. At the end of the 8th week of development the main sources of blood supply for the human costo-vertebral joints are branches of the segmental arteries, and at the end of the 12th week--those of the subclavian artery (the highest intercostal artery and the deep cervical artery) and those of the thoracic aorta (10 pairs of the posterior intercostal arteries). In the fetuses, variations in the course of the intercostal arteries have been revealed. The arteries situating within the costo-vertebral joints form extra organic branches which participate in blood supply of ligaments, articular capsules and cartilagenous epiphyses. Peculiar features in the angioarchitectonics of structural components of the costo-vertebral joints have been demonstrated. Interrelations of the blood vessels with some tissues of the costal head joint and the costo-transversal joints have been stated. The course and direction of capillaries in the cartilagenous tissue of the head, cervix and costal tubercle, and also in the transversal processes of the thoracic vertebrae have been described. No blood vessels have been revealed in the cartilage of the costo-vertebral joints.

Nutrient pathways of the cruciate ligaments. An experimental study using the hydrogen wash-out technique

We used the hydrogen wash-out technique to determine the rate of wash-out of an inert tracer from the posterior cruciate ligament in dogs and rabbits after we had detached the ligament from bone and synovial structures, and after we had isolated it from the synovial tissue with aluminum foil. These rates were compared with those from controls and no differences could be found between them. The uptake of tritiated proline administered intravenously was also shown not to be significantly different in the detached ligament as compared with an intact ligament. Isolation of the ligament from contact with the synovial lining prevented the uptake of hydrogen. Cruciate ligaments removed from the knee and placed in the suprapatellar pouch appeared viable after eight to ten days. These findings suggest that diffusion can serve as a major pathway for delivery of nutrients to the cruciate ligaments.

Nutrient pathways in transferred patellar tendon used for anterior cruciate ligament reconstruction

With the use of the hydrogen washout technique, nutrient pathways of a Jones-type anterior cruciate substitution in the dog were examined. There was no hydrogen uptake by the graft of patellar tendon left attached to the tibia but isolated from the synovium. However, when the graft was placed against synovium in the intercondylar notch, hydrogen uptake and washout were not significantly different than when the patellar tendon was completely intact (control). We conclude that, at least initially, direct blood flow does not contribute to nutrition and that synovial diffusion may play a significant role in the sustenance of the graft.

Microvasculature of the cruciate ligaments and its response to injury. An experimental study in dogs

The normal vascular anatomy of the cruciate ligaments was investigated in eight dogs by microangiography, histology, and tissue-clearing (Spalteholz) techniques. The vessels were found to originate predominantly from the soft tissues (infrapatellar fat pad and synovial membrane) of the joint. The vascular response to partial surgical transection of the anteromedial mid-portion of the anterior cruciate ligament was evaluated in twelve dogs. This response, which was vigorous and extensive, appeared to arise from the soft tissues. Resection of the infrapatellar fat pad and synovial membrane at the time of injury tended to decrease this response. Spontaneous healing of the defect had not occurred in either group by eight weeks.

CLINICAL RELEVANCE

The predominant soft-tissue, as opposed to osseous, origin of the blood supply to the cruciate ligaments may be an important consideration in the repair of these structures. The preservation and utilization of the infrapatellar fat pad and synovial envelope may optimize the vascular response and healing of the ligament.

Histochemical demonstration of adrenergic fibers in the fascia periosteum and retinaculum

Adrenergic nerve fibers were demonstrated in the fascia, periosteum and retinaculum using the formaldehyde method of Falck--Hillarp and the recently developed glyoxylic acid method. A typical adrenergic plexus was seen around the vessels. The arteries and arterioles received a dense adrenergic nerve supply. The veins had a sparse adrenergic innervation and the venules and capillaries were apparently without adrenergic innervation. These distribution patterns of adrenergic fibers were fundamentally similar to those seen in various organs. A difference in the pattern of innervation was seen, however, in the arterioles betweeen the fascia, and periosteum and retinaculum. Furthermore, chemical sympathectomy induced by injection of 6-hydroxydopamine resulted in the disappearance of noradrenaline fluorescence and marked vasodilation in the fascial vascular bed, and a moderate vasodilation in the periosteum and retinaculum. These findings suggest that the role of adrenergic fiber is vasoconstrictor and these fibers regulate the circulation in the fascia, periosteum and retinaculum.