Like the hip, the shoulder includes a ball and socket joint. The replacement of the shoulder joint is the operation which occupies the third place among common joint replacement, only after replacement of the hip and knee joints. Historically, shoulder replacement has a clear and defined objective which to restore or replicate the bone of the glenohumeral and the rotator cuff. The nature of shoulder arthroplasty is the most complex joint reconstruction in the human body. It need consider the factors of number and variation. With the development of surgical techniques and clinical physicians recognize, shoulder joint anatomy technology has made significant progress. With the development of surgical techniques and clinical physicians recognize, shoulder joint anatomy technology has made appreciable progress. The modem era of shoulder replacement is no more than thirty years old reach to present society. The conventional total shoulder arthroplasty (TSA) achieves this goal that it brings significantly improves function for many patients and reduces pain they suffer.
The cost of health care is increasing every year. There is a growing demand that the costs of treatment be justified by proven measurement of quality of life improvement. In determining the appropriate utilisation for joint replacement surgery, and thus defining its role in the treatment of degenerative disorders, effectiveness evaluation is critical. Regional variations in the frequency of joint replacement procedures and the lack of consensus regarding many aspects of related patient care, which have spurred interest in the methodology of surgical outcomes research. The aim is to better define the role of specific treatments through valid, evidence-based clinical outcome and epidemiological studies.
1 The development of the shoulder arthroplasty
The history of shoulder replacement can be dated from late 19th century France. A Parisian dentist, J. Michael Porter, who designed pean artificial shoulder which successful treat a patient whose shoulder was already tubercular infection. This operate can be classified as an original implant in the area of glenoid portion.(Lugli, 1978) In 1953, the Neer produced vanadium artificial humeral head prosthesis to treat humerus near end comminuted fracture and the result achieved satisfactory curative effect. From now shoulder arthroplasty began to be widely used in clinical treatment. The technique advanced extremely quickly in next few years. Since half shoulder arthroplasty (also called artificial humeral head prosthesis replacement, hemi-arthroplasty, HA) successful treated humeral fractures near end, this technique applied the scope of the shoulder joint replacement gradually spread to osteoarthritis, rheumatoid arthritis. This operation does not treat the shoulder joint disease that the both sides of the articulate surface head of the humerus and glenoid cavity have been broken. In 1970s, Neer added polyethylene glenoid cavity prosthesis on the artificial humeral head prosthesis, in order to develop the first generation which is Neerâ… total shoulder prosthesis system. Because the glenoid cavity prosthesis can easy be abraded, loosed and shoulder joint replacement overhaul technology not mature, clinical applications tend to use HA, but there are also glenoid cavity attrition problem. Biological surface angioplasty began to clinical applications in 1988, (Krishnan SG, 2007) in order to provide a method to solve glenoid cavity bring by the wear problem of the humeral HA prosthesis. At the same time, other types of the shoulder joint replacement technology also begins to appear and apply, such as artificial humeral head prosthesis surface replacement, shoulder arthroplasty flip angioplasty, and so on. At present shoulder arthroplasty has become a preferred method to treat most patients suffer from diseases of end-stage shoulder arthritis and humerus near end comminuted fracture. The current research mainly focused on the humeral head prosthesis and glenoid cavity prosthetic design, in order to reduce glenoid cavity wear.
2 the head of the humerus prosthesis replacement status
Shoulder joint prosthesis design for the main part of the head of the humerus. The study found that the curvature radius of the head of the humerus was inconsistent, in each section on the straight size is not the same. Now the head of the humerus prosthesis design is the head of the humerus diameter and thickness correlation coefficient as 0.75 (Gregory T, 2007) The size of the head of false body and the shoulder joint stabilization directly relate to the strength of surrounding muscle in shoulder arthroplasty. Not suitable prosthesis head will affect the head of the humerus normal center of rotation, change the shoulder joint lever arm around, so that the muscle function change, causes a shoulder to shoulder, surrounding soft tissue injury replacement failure. So first of all should choose appropriate false figure number to restore the humerus near end anatomy, then as reconstruction of soft tissue around the balance (Yuan benxiang, 2005).
Normal shoulder the head of the humerus and glenoid cavity are not matching, glenoid cavity surface curvature radius is bigger than the curvature radius of head of the humerus 2 ~ 3 mm, and the existence of articular cartilage and dishes lip in make them both basic matching. Shoulder arthroplasty "mismatch" refers to curvature radius of the head of the humerus prosthesis and glenoid cavity prosthesis are different, the ratio between them called consistent index, research shows that when the index is 0.80 ~ 0.88, joint stability is best (Anglin C, 2001). It is considered that it will be better if the glenoid cavity and the head of the humerus prosthesis in shoulder arthroplasty are totally matching from some theories, but in practice most scholars believe that do not match more conducive to the stability of the shoulder. The reason include two main point: one is that does not match the design can be in prosthesis dislocation happened when half the excess load transfer to the surrounding soft tissue, reduce direct action in the joints of dishes from mind load from mind load is the result of joint prosthesis loosening after one of the main reasons. The second point is that the relatively small head of the humerus false physical decrease attrition particle generation.
The design and selection of head of the humerus prosthesis depends on the length and the pulp cavity width. Medullary cavity width and humeral diameter relate to the thickness of the cortex, apparently show roughly wide at the top and narrow in the bottom. When intraoperative fully enlarge pulp help prosthesis handle with the surrounding bone, and to realize the full contact pressure distribution better, improve prosthesis handle stability.
At present, although the third generation of anatomical type prosthesis system already can well improve the prognosis of patients. Through the improvement of the head of the humerus prosthesis, prosthesis individual adaptability increased, shoulder function and the quality of life improved.
2.2 the head of the humerus prosthesis fixed technology
The head of the humerus prosthesis handle fixed means has bone cement and the bone cement two. Bone cement into the bone cement and near end bone cement fixed technology, non-bone cement is divided into pressure with fixed and compaction bone grafting.
3 glenoid cavity prosthesis replacement status
Glenoid cavity prosthesis has been use as clinical applications for 30 years, but it is still controversial. In the shoulder arthroplasty after use joint prosthesis will not only increase the operation time, intraoperative amount of bleeding and operation difficulty, and a series of postoperative complications may occur, especially glenoid cavity prosthesis loosening. Glenoid cavity prosthesis loosening is the result of operation failure, need to do shoulder joint replacement surgery is one of the main reasons for the revision.
3.1 glenoid cavity the applied anatomy and prosthesis design
Glenoid cavity prosthesis ideal design is to realize anatomical reconstruction, glenoid cavity the applied anatomy and biomechanics property of the prosthesis design has an important role. At present there are mainly the following dispute: (1) the glenoid cavity prosthetic material: all kinds of polyethylene prosthesis and metal tap of polyethylene prosthesis. (2) The shape of the glenoid cavity,Due to the glenoid cavity bone mass less, increase with age will cause bone loss, and progression of disease cause bone defect, and glenoid cavity form will be altered obviously, increase the difficulty of the anatomical reconstruction. In order to realize the anatomical reconstruction, scholars design the ultra-high molecular weight polyethylene wedge gasket to compensate for defect, preoperative adopts modern imaging technology after bone and joint damage, correct evaluation, in order to meet the individual treatment. Glenoid cavity prosthesis implantation mode: joint prosthesis after implant position to action in bone cement layer stress and glenoid cavity prosthesis have obvious influence on the load, prosthetic Angle can also affect the head of the humerus in glenoid cavity prosthesis position [16]. The study found that the glenoid cavity and shoulder blade body between axis Angle, Angle in the forward 2 ° and pour 7 ° between, after an average of 1.23 ° pour, glenoid cavity prosthesis downward sloping a batter to reduce the head of the humerus prosthetic shift, so glenoid cavity prosthesis implantation in moderate backward, downward sloping can better reduce partial mind load, and false body wear and loose (Yuan benxiang, 2005)
3.2 glenoid cavity prosthesis fixed technology
Glenoid cavity prosthetic fixed technology according to the fixed way into bone cement and the bone cement, according to the prosthesis design patterns into bolt fixed and keel fixed. At present most scholars think bone cement is not bone cement fixed more stable firm.
Neer design application first glenoid cavity prosthesis is made from polyethylene materials, oval, curved back, the bone cement and keel fixed, after 30 years of study the technical improvement is very small. Pure polyethylene, bone cement fixed, arc liner prosthesis design still is the best choice, the difference is bolt fixed than keel fixed more stable.
4 other technological progress
4.1 glenoid cavity biological surface angioplasty
In the presence of glenoid cavity prosthesis loosening and pure HA the glenoid cavity wear, glenoid cavity biological surface angioplasty began to clinical applications. It is in the basis of HA will joint capsule, broad fascia, Achilles tendon or meniscus and transplantation fixed on glenoid cavity, and "file dishes and activities to reshape" technology.
The angioplasty is mainly used in young and middle-aged patients, but compared with the TSA its curative effect is uncertain. Krishnan reported the shoulder arthritis using glenoid cavity biological surface angioplasty treatment after five years, it was found that glenoid cavity of wear and tear light, the head of the humerus prosthesis stability, did not occur secondary to false body wear and the dishes brachial arthritis, shoulder joint function is good. They think the glenoid cavity biological surface angioplasty can obtain and TSA similar clinical outcomes. The operation that young patients and to shoulder joint function demanding patients has a chance to pass a relatively long convalescence achieve good shoulder joint function recovery, and to avoid a joint prosthesis implantation after the risks of, but still need further evaluate its effectiveness and persistent. By using this technology is still need to be solved such as graft material source, its durability, surgical injury problems such as big. The development of tissue engineering make it become the solution of this problem is one of the most effective ways.
4.2 shoulder joint replacement revision procedures
Shoulder arthroplasty can appear for shoulder pain worse and functional limitations, need to shoulder joint replacement revision procedures. Neer will be its reason broadly grouped into the following three aspects: [2] : (1) the poor preoperative condition, such as rotator cuff injury, infection, etc.; (2) the operation and the false body of complications, such as during the operation, the structural damage, anatomical reconstruction failure; (3) the problems, such as rehabilitation exercise, poor dishes brachial joint continued instability. HA postoperative lead to overhaul the most common reason is glenoid cavity wear, TSA for dishes brachial joint continued instability and glenoid cavity prosthesis loosening
5 the market of shoulder joint replacement
The cost of health care is increasing every year. There is a growing demand that the costs of treatment be justified by proven measurement of quality of life improvement. In determining the appropriate utilisation for joint replacement surgery, and thus defining its role in the treatment of degenerative disorders, effectiveness evaluation is critical. Total joint replacement has become a viable alternative for young, middle-aged, and elderly patients who want to sustain athletically active lifestyles. Although shoulder arthroplasty can better ease serious shoulder joint disease patients clinical symptoms and improve with shoulder function, but at present the application more focus on low to the function requirement of the elderly patients. And in the clinical practice of many young and middle-aged patients because of the serious damage to the same shoulder surgery. The traditional surgery, ankle arthrodesis and joint operation from off the serious influence shoulder joint function and patient quality of life, young and middle-aged patients to joint functional requirement is high, the more hope the shoulder arthroplasty. To treat young and middle-aged patients with shoulder joint replacement, clinicians always hold more conservative. on the one hand, because of the shoulder joint is the whole body of large joints activity scope biggest joints, its activity intensity, more easy to cause prosthesis loosening and wear, especially glenoid cavity false body parts, shorten the prosthesis life; On the other hand because of shoulder joint overhaul technology not mature. But there are also clinicians claims for young and middle-aged patients with shoulder arthroplasty, because: (1) tell from the function upper limbs than lower limbs are more likely to avoid weight factors, can reduce false body wear; (2) from the surgery way, ankle arthrodesis and joint from off the shoulder joint function basic is lost, the serious influence patients quality of life, and shoulder arthroplasty can keep a certain extent with shoulder function, improve the quality of life. Burroughs [31] on 19 cases of mean age, 38.6 years of the young and middle-aged patients with shoulder joint replacement therapy, after a mean follow-up of 5.6 years, and from diseases and surgical types of classification discussion. The results showed that patients postoperative shoulder joint function and quality of life improved, no postoperative shoulder joint function deterioration, and TSA is HA has good curative effect. Sperling [32] reported so far the longest follow-up were the results of the study, this study included 78 patients with HA and 36 cases of patients with TSA, age are < fifty years old, and a mean follow-up of 16.8 years. The results showed that HA and TSA on pain relief and functional improvement of all can obtain long-term, steady effect, HA a TSA in quality of life better curative effect, but the expectation of life is relatively short and overhaul rate is higher. He thought that should be based on the individual situation of patients with disease progression and choose the right way of replacement. At present shoulder arthroplasty can make young and middle-aged patients get better and stable prognosis, But for the young and middle-aged patients with TSA or HA, is still controversial.
At present, the shoulder arthroplasty is still has many problems, the chosen replacement technology, fixed method and materials to get the best curative effect, still need large multicenter randomized controlled trials and long-term follow-up observation. A hot spot in the study of many focus on glenoid cavity part; Shoulder joint prosthesis system are mostly based on western people study design, with the popularization and application of technology in our country, how to design a more suitable for China's patients with shoulder joint prosthesis system; Whether can use tissue engineering theory and material better solve the glenoid cavity surface angioplasty are faced with the problem; For joint function of the high demand on the young and middle-aged patients, how can better improve the long-term prognosis. All these need further research to improve and confirmed.
LUGLI, TOMASO M.D, Artificial Shoulder Joint by Pean (1893): The Facts of an Exceptional Intervention and the Prosthetic Method, Clinical Orthopaedics & Related Research: June 1978 - Volume 133 - Issue - ppg 215-218
Krishnan SG, Nowinski RJ, Harrison D, et al. Humeral hemiarthro plasty with biologic resurfacing of the glenoid for glenohumeral arthritis-Two to fi fteen-year outcomes. J Bone Joint Surg (Am), 2007, 89(4): 727-734.
Gregory T, Hansen U, Emery RJ, et al. Developments in shoulder arthroplasty. Proc Inst Mech Eng H, 2007, 221(1): 87-96.
è¢æœ¬ç¥¥, 董英海. 肩关节应用解å‰-与å‡ä½“设计. 临床骨科æ‚å¿-, 2005, 8(6): 571-573.
Anglin C, Wyss UP, Nyffeler RW, et al. Loosening performance of cemented glenoid prosthesis design pairs. Clin Biomech (Bristol, Avon), 2001, 16(2): 144-150.
Boileau P, Avidor C, Krishnan SG, et al. Cemented polyethylene versus uncemented metal-backed glenoid components in total shoulder arthroplasty: A prospective double-blind, randomized study. J Shoulder Elbow Surg, 2002, 11(4): 351-359.
