'The Sneaky Plica' revisited: morphology, pathophysiology and treatment of synovial plicae of the knee.

PURPOSE: To comprise current knowledge on morphology, embryology and pathophysiology of synovial plicae as well as on clinical and therapeutic aspects of the plica syndrome. METHODS: Review of the literature combined with a meta-analysis of studies assessing the outcome of open or arthroscopic plica excision including the author's own series. RESULTS: The term synovial plica has been devised to describe a number of intra-capsular folds thought to represent remnants of a membranous knee joint partition present during foetal development. Although four such folds have been defined, it is mainly the medial patellar plica which is implicated in carrying clinical significance as a potential cause of anteromedial knee pain particularly in adolescents. Blunt trauma, a sudden increase in athletic activity or any form of transient synovitis are associated with plica inflammation leading to tissue fibrosis and subsequent loss of elasticity. A plica affected in this way may impinge against intra-articular structures in its proximity, often creating localised chondromalacia particularly of the patello-femoral joint. The diagnosis is based on history and clinical examination although MRI can be of value. Twenty-three studies assessing the clinical out-come of 969 patients following open or arthroscopic plica excision were identified. The average age was 25 years with equal male-to-female ratio. Trauma was considered the cause in 57 %. At a mean follow-up of 27.5 months, 64 % of patients were symptom free, 26 % improved and 10 % considered failures. CONCLUSION: Symptomatic plicae may initially be treated with physiotherapeutic measures and structured exercise regimes but success rates are generally low. Intra-plical or intra-articular corticosteroid injections may be beneficial if administered early in the disease process. Arthroscopic excision of the entire plical fold becomes indicated in recalcitrant cases and once a plica has undergone irrevocable morphological changes. The procedure carries low morbidity, and results are universally good especially if the plica is the sole pathology. Factors associated with a favourable outcome are young patient age, localised symptoms of short duration and absence of plica induced chondromalacia.

The story of anterior cruciate ligament reconstruction--part 2.

The first part of The story of anterior cruciate ligament reconstruction, was published in the previous issue of this journal, and the reader is encouraged to study both parts in order to become better acquainted with the subject. Those who have read the first part will remember that it concerned the historical developments surrounding the ligament's discovery, the acknowledgement of its function and the appreciation of the detrimental effects once it becomes damaged. It also described the efforts of the early pioneers who recognised the need to reestablish ligament function by ways of ligament repair or reconstruction with autologous tissue. The second part, presented here, explores the surgeons' quests to find the ideal graft material by experimenting with various synthetic materials, as well as those derived from animals (xenografts) and other human beings (allografts). It looks at historic efforts to stabilise an unstable knee by means of extra-articular reinforcements which were popular until not too long ago and reviews the developments of the various graft fixation methods available today. Furthermore it evaluates the influence of arthroscopy which revolutionised not just the procedure of ACL reconstruction but knee surgery in general, and also focuses on the more recent developments of double bundle techniques and the recreation of the ligament's native anatomy.

The story of anterior cruciate ligament reconstruction--Part 1.

Once upon a time the anterior cruciate ligament (ACL) enjoyed a relatively unchartered existence, when only a fall from a jousting horse or chariot might have sent a knight or gladiator into early retirement due to an unstable knee. In today's world of high speed travel and an ever increasing number of sports enthusiasts, injuries of the ACL are almost common place with a yearly incidence of about 35 per 100,000 of the population. Although we have known about the existence of the cruciate ligaments since they were first described by Galen over 2000 years ago, awareness of their function and the consequences of their loss were not appreciated until much later. Robert Adams observed the first clinical case of an ACL tear in 1837 but treatment in those days was largely conservative and surgery was reserved for life threatening conditions as mortality was high. The first ACL repair was performed in 1895 by Mayo-Robson of Leeds and was followed by Grekow and Hey Groves who initiated ACL reconstruction with autologous tissue between 1914 and 1920, almost as we know it today.

Basic kinematics and biomechanics of the patellofemoral joint part 2: the patella in total knee arthroplasty.

Patellar and femoral component in total knee arthroplasty are inextricably linked as a functional unit. The configuration of this unit has been a matter of ongoing debate, and the myriad of different patellar and femoral components currently available reflect the lack of consensus with respect to the ideal design. One of the major challenges is to overcome the biomechanical disadvantages of a small contact area through which high contact pressures are transferred, making this mechanical construct the weakest part of the prosthetic knee. Contact areas are highly dependent on the congruency of the patellofemoral joint articulation, and are significantly smaller for dome shaped patellar components compared to those of more anatomic designs. However, when exposed to 3-dimensional movements, the contact areas of the dome shaped patella are significantly greater, indicating enhanced forgiveness regarding patellar malpositioning. Although contact stresses, a function of implant design and surface conformity, can reach levels far beyond the yield strength of UHMWPE, catastrophic failure of resurfaced patellar components, commonly seen in metal backed patellae, fashionable in the 1980s, has rarely been observed since. Although plastic deformation and wear of UHMWPE continue to represent a problem, in the absence of suitable alternatives polyethylene remains the bearing surface of choice. The appreciation of the consequences of the mechanical environment on the behaviour of the patellofemoral joint is of particular importance in the endeavour to develop knee replacement systems which provide satisfactory function together with clinical long-term success.

The controversy of patellar resurfacing in total knee arthroplasty: Ibisne in medio tutissimus?

Early arthroplasty designs were associated with a high level of anterior knee pain as they failed to cater for the patello-femoral joint. Patellar resurfacing was heralded as the saviour safeguarding patient satisfaction and success but opinion on its necessity has since deeply divided the scientific community and has become synonymous to topics of religion or politics. Opponents of resurfacing contend that the native patella provides better patellar tracking, improved clinical function, and avoids implant-related complications, whilst proponents argue that patients have less pain, are overall more satisfied, and avert the need for secondary resurfacing. The question remains whether complications associated with patellar resurfacing including those arising from future component revision outweigh the somewhat increased incidence of anterior knee pain recorded in unresurfaced patients. The current scientific literature, which is often affected by methodological limitations and observer bias, remains confusing as it provides evidence in support of both sides of the argument, whilst blinded satisfaction studies comparing resurfaced and non-resurfaced knees generally reveal equivalent results. Even national arthroplasty register data show wide variations in the proportion of patellar resurfacing between countries that cannot be explained by cultural differences alone. Advocates who always resurface or never resurface indiscriminately expose the patella to a random choice. Selective resurfacing offers a compromise by providing a decision algorithm based on a propensity for improved clinical success, whilst avoiding potential complications associated with unnecessary resurfacing. Evidence regarding the validity of selection criteria, however, is missing, and the decision when to resurface is often based on intuitive reasoning. Our lack of understanding why, irrespective of pre-operative symptoms and patellar resurfacing, some patients may suffer pain following TKA and others may not have so far stifled our efforts to make the strategy of selective resurfacing succeed. We should hence devote our efforts in defining predictive criteria and indicators that will enable us to reliably identify those individuals who might benefit from a resurfacing procedure. Level of evidence V.

Surgery for anterior cruciate ligament deficiency: a historical perspective.

The anterior cruciate ligament (ACL) has entertained scientific minds since the Weber brothers provided biomechanical insight into the importance of the ACL in maintaining normal knee kinematics. Robert Adams described the first clinical case of ACL rupture in 1837 some 175 years to date, followed by Mayo-Robson of Leeds who performed the first ACL repair in 1895. At that time, most patients presented late and clinicians started to appreciate signs and symptoms and disabilities associated with such injuries. Hey Groves of Bristol provided the initial description of an ACL reconstruction with autologous tissue graft in 1917, almost as we know it today. His knowledge and achievements were, however, not uniformly appreciated during his life time. What followed was a period of startling ingenuity which created an amazing variety of different surgical procedures often based more on surgical fashion and the absence of a satisfactory alternative than any indication that continued refinements were leading to improved results. It is hence not surprising that real inventors were forgotten, good ideas discarded and untried surgical methods adopted with uncritical enthusiasm only to be set aside without further explanation. Over the past 100 years, surgeons have experimented with a variety of different graft sources including xenograft, and allografts, whilst autologous tissue has remained the most popular choice. Synthetic graft materials enjoyed temporary popularity in the 1980 and 1990s, in the misguided belief that artificial ligaments may be more durable and better equipped to withstand stresses and strains. Until the 1970s, ACL reconstructions were considered formidable procedures, often so complex and fraught with peril that they remained reserved for a chosen few, never gaining the level of popularity they are enjoying today. The increasing familiarity with arthroscopy, popularised through Jackson and Dandy, and enhancements in surgical technology firmly established ACL reconstruction as a common procedure within the realm of most surgeons' ability. More recently, the principle of anatomic ACL reconstruction, aiming at the functional restoration of native ACL dimensions and insertion sites, has been introduced, superseding the somewhat ill-advised concept of isometric graft placement. Double-bundle reconstruction is gaining in popularity, and combined extra- and intra-articular procedures are seeing a revival, but more accurate and reliable pre- and post-operative assessment tools are required to provide customised treatment options and appropriate evaluation and comparability of long-term results. Modern ACL surgery is united in the common goal of re-establishing joint homoeostasis with normal knee kinematics and function which may ultimately assist in reducing the prevalence of post-operative joint degeneration. This review hopes to provide an insight into the historical developments of ACL surgery and the various controversies surrounding its progress. Level of evidence V.

Basic kinematics and biomechanics of the patello-femoral joint. Part 1: The native patella.

The patello-femoral joint (PFJ) enhances our ability of knee flexion and extension and is assumed to have evolved through men's ability of having adopted a bipedal gait. This articulation between patella and femur is relatively complex and displays intricate biomechanical behaviour. Forces in the patello-femoral joint are a function of the quadriceps force, and the angle of flexion of the knee. They are highly dependent on the distance between the patello-femoral joint and the centre of gravity, which explains why different activities despite equivalence in tibio-femoral angle may exert wide variations in patello-femoral reaction forces and contact pressures. During normal daily activities the PFJ becomes exposed to force values between 0.5 to 9.7 x body weight, whilst sporting activities create force values that approach up to 20 x body weight. Those forces are considerable and it is therefore not surprising that the PFJ is particularly susceptible to degenerative disease especially if its mechanical equilibrium is disturbed through injury, muscle weakness and congenital or developmental abnormalities. The clinician must be aware of biomechanical and kinematic specifics, the high patellofemoral load values, small patellofemoral contact areas, and resultant high stress magnitudes when trying to remedy such abnormalities.

Current concepts of articular cartilage repair.

Articular cartilage provides a vital function in the homeostasis of the joint environment. It possesses unique mechanical properties, allowing for the maintenance of almost frictionless motion over a lifetime. However, cartilage is vulnerable to traumatic injury and due to its poor vascularity and inability to access mesenchymal stem cells, unable to facilitate a satisfactory healing response. Untreated chondral defects are thus likely to predispose patients to the development of osteoarthritis. Reconstitution and repair of articular cartilage is dependent on the neosynthesis or implantation of cartilage matrix elements, a goal which can be achieved through a variety of surgical means. Commonly used repair techniques include marrow stimulation, structural osteo-articular autografts or chondrocyte implantation. Despite substantial differences in the complexity and technical application of each method, all are united in the endeavour to restore joint function and prevent joint degeneration. Anyone attempting to treat cartilage defects must possess a basic understanding of the physiology of cartilage growth, and relevant factors affecting cartilage healing and repair. Furthermore, knowledge of the biomechanics and kinematics of the knee are essential in order to appreciate the forces acting on joint surfaces and repair tissues. Although clinical success is dependent on appropriate patient selection, accurate clinical assessment, definition of root causes and application of the right choice of treatment modality, the ultimate outcome of any intervention remains heavily reliant on the surgeon's proficiency in the technical aspects of the chosen surgical procedure.

The practice of unicompartmental knee arthroplasty in the United Kingdom.

PURPOSE: To survey the current practice of unicompartmental knee arthroplasty (UKA) in the United Kingdom. METHODS: Questionnaires were sent to all 341 local members of the British Association for Surgery of the Knee to inquire into their practice of UKA, including clinical indications, preoperative investigations, surgical approach, preferences in implant design, and the role of UKA in relation to high tibial osteotomy. RESULTS: 56% of respondents performed less than 16 UKAs per year, whereas 16.5% performed over 30 per year. 89.5% of the respondents used anteroposterior radiographs as their main investigation tool. Only 30% and 16.5% used posteroanterior 30 degrees flexion and varus/valgus stress radiographs, respectively, despite being better investigation tools. 57% considered arthroscopy, despite its invasive nature. The main contra-indications to UKA were anterior cruciate ligament deficiency with instability (95%), focal grade-III osteoarthritis in the contralateral compartment (87%), and osteoporosis with rheumatoid arthritis (80.5%), but only 59% of respondents considered an inability to passively correct a pre-existing varus or valgus deformity as a contra-indication. 51.5% of respondents preferred minimally invasive approach, 96% preferred cemented fixation, and over two thirds used the mobile bearing design. 72% of respondents expressed preference for total knee arthroplasty over UKA in localised lateral compartment osteoarthritis. CONCLUSION: Modern UKA has gained popularity in properly selected patients with localised medial compartment osteoarthritis, provided the knee is not anterior cruciate ligament deficient and any deformity is passively correctable.

Cartilage repair using autologous chondrocyte implantation techniques.

Articular cartilage in adults has a poor ability to self-repair after injury. A variety of cartilage resurfacing techniques have the potential to improve the repair of cartilage defects and reduce the patient's disability. The most advanced of these techniques is autologous chondrocyte implantation. It promises to provide normal organogenesis leading to histologically and functionally normal articular cartilage. The procedure is technically demanding and requires patients to adhere to a specific post-operative rehabilitation protocol. Clinical results have so far been encouraging and have allowed many patients to resume high levels of sporting activity.

Minimally invasive surgery of the knee.

Minimally invasive knee replacement surgery has been developed in an attempt to lessen the impact of operations on the patient's quality of life, in the same way as arthroscopy, the forefather of minimally invasive surgery (MIS), revolutionised cartilage and ligament surgery three decades earlier. The technique is based on minimising soft tissue and muscle trauma, skin incision length, and capsular disruption while trying to maintain the ultimate goal of a well-aligned, well-fixed knee replacement. Short-term advantages including accelerated recovery and reduction in blood loss have been demonstrated, but it remains to be investigated whether MIS is able to provide sustainable benefits and long-term outcome equivalent to conventional surgery. Successful application of MIS techniques have been confirmed in conjunction with unicompartmental knee arthroplasty (UKR) implantation, while its use with total knee arthroplasty remains experimental. Critics have expressed concern that reduced visibility may compromise implant positioning and leg alignment which could have a negative effect on prosthetic long-term survival. MIS clearly represents a unique and more technically demanding procedure, but the learning curve may perhaps overshadow the benefits. Computer navigation may help to avoid such problems but so far scientific evidence regarding definitive outcomes is lacking, and some of the MIS techniques are still in the early phases of development.

Use of a novel bone graft substitute in peri-articular bone tumours of the knee.

We treated three patients with aneurysmal bone cysts and seven with giant cell tumours who presented with a large osteolytic lesion in peri-articular areas of the knee. The patients age ranged from 8 to 49 years (mean 25 years). The average tumour volume was measured at 39.8 cm(3) (range 18 to 65 cm(3)). The tumour cavities were treated with curettage, phenolisation and application of a composite bone graft substitute containing 35% calcium-sulphate hemihydrate and 65% hydroxyapatite granules. All patients were followed up for 4.0 to 5.2 years (mean 4.5 years). Tumour recurrence was noted in two cases. In the remaining patients consolidation of the lesion was considered complete at a mean of 4.5 months (3-6.5 months). During follow-up no deformities developed and no radiological signs of joint degeneration were noted. All patients regained close to normal function, with a mean Musculoskeletal Tumour Society Rating Score of 95.1%. Due to their good osteoconductive abilities, composite synthetic bone graft substitute combining porous hydroxyapatite with calcium-sulphate appears to be an effective alternative to autologous cancellous bone graft in the treatment of large osteolytic lesions in peri-articular areas around the knee joint. They bear major advantages through ubiquitous availability and the avoidance of morbidity associated with iliac crest harvest. Concerns remain as the radio-opaque appearance of the bone graft substitute may potentially delay the detection of tumour recurrence.

Retroperitoneal giant schwannomas: report on two cases and review of the literature.

The occurrence of massive retroperitoneal schwannomas is extremely rare and their presence may only be expressed by insidious onset of non-specific and misleading symptoms with a predominance of lower back pain. MRI scan as the imaging procedure of choice will demonstrate the tumour location and its relation to the surrounding structures, but due to heterogeneity and degeneration in some tumours, it may mimic malignancy. Hence tissue sampling through needle biopsies are essential to verify the diagnosis prior to surgery. Tumour excision in toto is considered the treatment of choice, but it can be hazardous especially if the tumour is adherent to the presacral venous plexus. Severe bleeding complications due to the damage of venous structures have to be encountered, and establishing lasting haemostasis may pose considerable difficulties. Hence surgery should be attempted with full precautions, and preoperative counseling of the patient. If malignancy can safely be excluded, laparoscopic piecemeal excision should be considered as an alternative treatment as recurrence is unlikely. Definition of the originating nerve might not always be possible and a minor degree of neurological impairment has therefore to be anticipated.