Knee replacement is undertaken when a patient has diseases that affect the knee such as rheumatoid arthritis and osteoarthritis or due to knee injury or old age. An artificial implant is used to replace the damaged knee during surgery. There are many companies making these knee implants in the world. Therefore, this review essay discusses advances in knee replacement surgeries and compares the different techniques and implants used. It also examines the different manufacturers of knee implants. This paper will also compare the market for knee implants globally especially between developed and developing countries. Also, compare the market for knee replacement in both the US and Europe, and find why it is less expensive in Europe. Finally, the paper concludes with the future of the knee replacement market.


Knee replacement is necessitated by a number of factors such as injury, inadequate movement of the knee joint and lack of response to medication. This procedure would “involve replacing an injured or diseased joint with an implant to relieve pain and improve movement.”[1] There are two types of knee replacement approaches: (1) total knee replacement (TKR) and (2) partial knee replacement (PKR).

The first breakthrough knee replacement surgery was in 1968 when the first surgery was done. Since then there have been tremendous advancement in knee replacement procedure and technique making it among the most successful medical procedure. It is projected that the number of knee replacement procedure will continue to increase year after year. This could be to factors that lead to lack of proper functioning of the knee such as arthritis that can result in the damage of cartilage and joint bones.

The following are some of knee problems that might lead to knee surgery. (1). Osteoarthritis: this is an age-related wear and tear on the knee joint and usually occurs in older people older especially those above50 years old (2). Rheumatoid arthritis: this diseasecauses “the immune system to attack the membranes in the knee and creates damage and cartilage wear”[2] (3). Traumatic arthritis is due knee injury and results in the weakening of joints (4). avascular necrosis (AVN),  most people affected by this condition are teenagers and young adults. This condition involves the softening of bones in the knee resulting in wearing down of cartilage and bone. When this wear is extensive, it may require surgery (5) abnormal alignment or formation of the knee.


The knee consists tibia (shin bone), femur (thighbone), patella (kneecap), cartilage, synovial membrane, ligament, (elastic connective tissue), tendon (connective tissue), and meniscus. Knee surgery could involve any of the aforementioned parts of the knee due to damage or tear and wear causing pain and difficulty in movement and walking. Therefore, surgery may be done to replace the injured parts of the knee. Injured parts are frequently replaced by metal parts and plastics in respect to the condition of cartilage, ligament, femur or tibia.

Surgery normally takes from one hour to several hours under general anesthesia. In certain cases for precision, the doctor may utilize a robotic arm system that perfectly determines the damaged surface and aligns the knee implants in the correct position or place. Such type of surgery is known as computer-assisted surgery.

There are several factors that are considered when the doctor is offering prostheses, which include the patient’s level of the damage in the knee, work level, age and body weight. Additionally, there are different types of knee replacement devices used in either total implants or partial implants depending on the state of the knee.

Types of Knee Replacement

Total Knee Replacement (TKR)

Total knee replacement is the traditional way of repairing a damaged knee. Since 1968 when it was first performed doctors have improved total knee replacement techniques that it now ranks among the safest and efficient and effective form of surgery. Total knee replacement is only recommended if the three major parts of the knee “joint’s compartments are damaged.” The procedure for a total knee replacement involves the doctor eliminating the surface of the damaged bones and replaces it with an implant that fits the patient. The damaged bone is precisely cut off and the remaining bone is shaped to match the artificial knee implant.[3]Essentially, there are four steps in the surgery. First step is preparation of the bone by cutting away the damaged cartilage found at the ends of the tibia and femur. In the second step the surgeon fits the implants by either cementing them or press-fitting it to the bone. The third step involves the insertion underneath the patella of a plastic button. In the final step, the doctor implants a plastic spacer between the femoral and tibial metal components to create a smooth surface similar to that of a normal knee.[4]

Types of Total Knee Replacement (TKR)

There are two types of total knee replacement surgeries namely, cruciate retaining and posterior stabilized.

1. Posterior Stabilized

When the posterior cruciate ligament cannot support the knee implant then the surgeon removes it and replaces it with special implant components that stabilize the knee.

2. Cruciate Retaining

This is done when the knee ligament is able to support an artificial knee implant and therefore it is not removed and used to support the prosthesis. Therefore, in this case “the artificial joint used is “cruciate-retaining” and has a groove in it that accommodates and protects the ligament.”[5]

Partial Knee Replacement Surgery

Partial knee surgery or replacement is when the surgeon “resurfaces only one or two compartments of the knee”.[6] This means that the healthy bone and tissue is spared so as to that the healing process is faster or requires less time. 

Types of Partial Knee Replacement

There are three types of partial knee replacement, depending on which part of the knee, which is damaged. However, each type of partial knee replacement surgery requires a different surgical method and different implant. The opening made or incision is always smaller than the one done when total knee replacement is done.

1. Unicompartmental surgery: this involves the replacement of only one compartment of the knee.

2. Bicompartmental Partial replacement: this is where the surgeon replaces both compartments of the knee.

3. Patellofemoral Surgery: this is where the surgeon “replaces the end of the thigh bone with a metal piece and resurfaces the backside of the knee cap”.[7]

Types of Knee Implants

Different types of knee implants are available depending on the problem of the patient and the doctor involved in the surgery. Total knee implants are used to replace the whole damaged knee while partial knee implant used to substitute only the injured part of knee.

Types of Total Knee Implants

Total knee implants are designed according how they will be fixed and materials used vary accordingly from case to case. For example, one may be given a mobile bearing implant or fixed, posterior cruciate ligament retaining implant or posterior cruciate substituting implant.

Fixed Bearing Implants

The most common type of total knee replacement implant. It known as “fixed because the polyethylene cushion of the tibial component is fixed firmly to the metal platform base.”[8] Due to the fixed nature are not able to withstand vigorous activity and a lot of weight. Such aforementioned activities can result in the disfunctioning of the implant.[9]

Mobile Bearing Implants

This type of implant is recommended for younger people, people with many activities and those whom may be obese because they can withstand vigorous activity and more durable than the fixed knee implants. The bearing surface is what differentiates mobile bearing implants and medial-pivot implants. These implants are more expensive than the fixed bearing implants. Mobile bearing implants give more room for the movement of the knee and maneuverability is much more enhanced than of the fixed bearing implants. However, they require strong attachment to the ligaments around the knees.[10]

Medial Pivot Implants

This implants mimics the natural knee as it rotates, bends, twists and stable like the normal knee. Medial pivot implants has the advantage of being stabile during knee movement. They are more expensive than the other implants and require stronger soft tissue for them to function well. 

Types of Knee Implant Fixation

Fixation is what makes the difference in all kinds of knee prosthetics. Fixation comes in three types namely cemented, cementless and hybrid. Cemented implants are made a special bone cement that helps to hold the different components of the implant in place. Almost all knee implants are of this type. Cementless implants require or depend on the growth of bone into the artificial implant to get fixed. The unique feature of this design is that its surface is coated with a permeable material that allows the new bone to propagate into the prosthetic. In certain cases, screws are used to strengthen the implant until the bone has grown. This means that the time for healing is much longer as it has to wait for the bone to grow and be attached to the implant.[11]

Types of Knee Replacement Approaches

The approach to be taken in knee replacement depends on the doctor what is suited for the patient. The doctor concern engages the patient and explains the procedure to be taken. The approaches taken can be traditional surgery, minimal invasive surgery among others.

Traditional Surgery

In this approach, the standard surgical technique is used where the doctor makes an eight to twelve inch incision along the front towards the middle of the knee. Another technique used is the making of an incision along “the front of the knee to the side of the knee.”[12] Essentially, this technique includes cutting the quadriceps tendon and exposition of the arthritic joint. After the surgery, approximately twelve weeks are required for sufficient recovery.[13]

Minimally Invasive Surgery

This is done in order to minimize trauma to the knee tissue, help in decrease of blood loss and lesser pain. There is a reduction in the incision to between three to four inches. Due to less trauma to the tissue healing period is reduced and better movement of the knee after the recovery. The same artificial prosthetics implants used in traditional surgery are the same utilized in this procedure. This is technique is effective because manufacturers have made specialized instruments that are used during the surgery.[14]

Types of minimally invasive approaches

Quadriceps-Sparing Approaches

            Another name of this approach is “subvastus.” After “the minimal incision is made, the kneecap is pushed to the side”[15] and the arthritic bone is cut without damage to the quadriceps tendon. In this approach, there is a less invasive than the traditional way of surgery sparing the quadriceps muscle from any damage. Another variation of this approach is known as “midvastus” which involves the splitting of the muscle “along a natural line through the middle”.[16]

The midvastus and subvastus approaches require more time to perform but the advantage is that shorter time is needed for rehabilitation as minimal trauma is suffered by the underlying thigh muscle.

Lateral Approach

This method is used for patients with knees that have the tendency to bend outwards and therefore this technique is seldom used.[17] The doctor approaches the knee from the side. Since it is less invasive than the traditional surgery the patient recovers fast and able to walk in a short duration.  

Minimally invasive approach enables patients to leave the hospital in the shortest time possible, resume their daily activities, shorten the healing period, and experience minimum pain. However, these approaches are not applicable to every patient and it is upon the surgeon to evaluate and decided the best surgery for the patient.

Computer-Assisted Surgery (CAS)

Computer-assisted approaches are become popular with surgeons performing both total knee replacements and partial knee replacements where both minimal invasive and traditional approaches can be applied. The patient’s data is entered into a computer, which then creates a 3-D picture of the injured knee. The software assists the surgeon by providing accurate image of the knee. Moreover, the computer assists the doctor in the alignment of the implant ensuring that the implant will be at the correct place increasing effectiveness and reliability of the implant. Computer aided surgery also decreases recovery period and help the surgeon make a smaller incision.[18]

Why is it less expensive in Europe?

In the US, the makers of implants have perfected the art inflating the prices of these products. In the sale of these implants there many intermediaries who increase the prices. It is noted that in the America the prices of implants rise by more than five percent each year. These knee implants are also made by four major companies, DePuy Synthesm , Zimmer, Stryker and Smith & Nephew, which have formed a cartel. Moreover, these companies modify old models of the same implants and market them as new products deliberately and therefore charging exorbitant prices claiming that they are new inventions.[19]

Foreign made knee implants are prevent from coming into the US market by patents, trade policies and long, tedious and expensive approval procedures by the Food and Drug Administration Authority. In essence, the “companies defend this turf ferociously”.[20] Although, all the five companies almost similar models, each company nurtures powerful brand loyalty by having financial links to surgeons and use of different modalities of installing the implants on patients as a result the surgeons are more comfortable with the system they have learnt and are unwilling to change. 

Clinics and hospitals have also less bargaining power with the manufacturing companies since they buy in small quantities from any of the manufacturing companies. Moreover, the companies require hospitals, doctors and clinics to sign agreements where they cannot disclose the prices of the knee implants, essentially meaning that they cannot compare prices. This practice erodes the ability of hospitals and surgeons to bargaining opening the flood gates for profit making intermediaries and brokers to make more money pushing the prices higher.

However, in Europe it is different as many European countries such as Belgium oversee medical purchases, approve many different types of knee implants from the manufactures, they also determine the allowed prices for the implants depending on its model. In addition, manufacturers are not allowed to sell implants at exorbitant prices as in the United States.[21]

Comparing the market for knee replacement in both the US and Europe

The aging population and increase in occurrence of diseases such as arthritis is the driving force behind the increase in European knee replacement market. Knee replacement in European experience growth in 2012. This growth has been due to increased number of patients, and advancement in diagnostic techniques. The same companies that make knee implants in the US and the same that dominates the European market either through their parent companies or through subsidiaries.

The US and European market if full of companies offering different types of knee prosthetics from total knee to partial knee replacement solutions. The continuous occurrences of diseases such as arthritis and a population growing old are driving needs for implants and the market higher each year.  The requirement for total knee replacements implants represent the bulk of the market. In the US there is continuous invention in the area of implants plus support from the government agencies make the US market lucrative for leading companies such as DePuy Synthesm , Zimmer, Stryker and Smith & Nephew. The following four DePuy Synthesm, Zimmer, Stryker and Smith & Nephew are the most successful companies in the US and Europe accounting for a large share of the market.

Different manufacturers of knee implants in US and Europe

The largest manufacture of knee implants in the world is Zimmer Manufacturing Company founded in 1927 by Justin Zimmer. Zimmer controls 26 percent market share of the global knee implants industry. It started selling knee implants in 1968. Selling products in more than 100 countries, it has the largest coverage in the world dominating both the US and European markets. Zimmer has manufacture what it calls the Next Generation (NextGen) knee implant which it claims to improve motion of the knee. Since its release in 1995, three million of these implants have been sold. However, there have been lawsuits concerning this product because of patients who required revision surgery because of faults with the knee implant.[22] Younger, more active patients are the target demographic for this knee implant, which was released in 2001. The NexGen Flex line was also heavily marketed to people whose cultural background or religious beliefs require extensive kneeling for prayer.

The second largest manufacturer of knee implants in the world is DePuy. DePuy was founded in 1895 by Revra DePuy and was the first company to make orthopaedics. This company merged with Johnson & Johnson in 2011 to form the DePuy Synthes Companies of Johnson & Johnson. This company in 2010 controlled 22.7 percent share of the knee prosthetic market. DePuy manufactures artificial knee implants for total knee replacement surgery and also partial knee replacement surgery.[23]

Stryker is the third largest manufacture of knee implants both in US and Europe. Stryker is a US based company and a leading company in prosthetic technology in the world. It has produced high quality knee implants that rival those of Zimmer and DePuy synthes.

Smith & Nephew is the biggest manufacturer of knee implants in Europe as by the posted higher sales in the year 2014. It sales has increased by nine percent in the last three months reaching 1.1 billion dollars. This is due to increase in sales of knee implants in the United States and could be due to expected changes in the health care system. In Europe there is increase in sales but as much as the company had expected due to recession and decline in popularity of some of its implants. The new strategy of Smith & Nephew is to aggressively expand into the Asian market.

Developing World

The market for prosthetics in Asian countries such as Japan, China and India is projected to grow considerably. The combined population of these Asian countries make knee implants business in this region very lucrative. For instance, in the year 2012 the market in Japan was in the excess of 1.3 billion dollars while in China the knee implant business was 364 million dollars.[24] Therefore, small manufactures of knee implants in Asian countries such as India, Japan and China are making billions. Moreover, other Asia companies with subsidiaries in the US are trying to manufacture customized prosthetics for this market. For examples, Singapore based Maxx Medical has released a new type of implant customized especially for India with an aim of being among the top knee implants manufacturers in India in the next 3 years after Zimmer and Johnson & Johnson. In India it is estimated that the knee replacement market is around 50,000 implants per year and it is projected to rise. Maxx Medical also plans to venture into the Asia market in Philippines, Thailand, and Malaysia. Currently, Maxx Medical sells knee implants in Europe, Gulf and United States.[25]

Some Asian knee implants manufacturers have also gone global. For instance, a Korean company known as Corentec Company Ltd has advanced into the American market. In 2012 it established a subsidiary in California known as Corentec America which supplies the American market with knee replacement implants although it manufactures these prosthetics in Korea.

However, in the developing world countries such as India and China the most successful companies in terms of selling knee implants are still European and United States companies and their subsidiaries such as DePuy synthesis, Stryker and Zimmer. This is due to their production of high quality knee implants and the enormous amount of money dedicated to research and marketing in the developing countries. Zimmer, Stryker and DePuy Synthes in that order are the three most important companies that control the knee replacement market in India and even Japan. However, in china Smith & Nephew has the majority shares in that market followed by Stryker. In India, Johnson & Johnson has the largest share of the market.[26]

In the manufacture of knee implants parts Depuy Synthes is ranked number one in Japan and China in terms of market shares followed by Acumen. Other companies in this category, Stryker is ranked first in the Indian market but also has a strong presence in Japan and China.[27]

In the recent past Asian companies have also started being competitive and gaining part of the market from the big US and European companies. This has been due to government policies that encourage local companies presence in their respective countries coupled with lower prices of the implants. This is especially in China and India. Small companies in these two countries due to less regulations have started manufacturing lower priced implant parts. Although, there quality may be questionable comparing to those of US companies they have been successful in their domestic markets. Also, these small companies are thriving due to low incomes and difficulties in accessing health insurance of the citizens of these countries. Some successful companies in Asia include Weigao, Nakashima medical and Sancheti.[28]

In some countries such as China and India the European and American companies due to stiff competition from the local companies have established domestic factories to make low-costs resembles of their of their high quality products that they sell in Europe and the United States. Additionally, they have bought or are in partnership with local companies that have a large market share in these developing countries which increase their competitiveness and increase the range of products they offer. For instance, in 2010 Zimmer in order to increases its market share in China acquired Beijing Montagne Medical Device Company. In the 2012, Medtronic acquired China based Kanghui Holdings for more than 750 million dollars which was the largest local manufacturer of prosthetics.[29]

It is worth noting that the Japanese market almost resembles the American market in terms of regulations, quality of the products and ability of the population to afford medical care. However, the market in Japan is different from the American market in terms of high number of regulations concerning novel implants. These regulations have proved difficult for US and European manufacturers trying to dominate this market. Foreign companies face challenges in the Japanese market because they are unable to market expensive and new products.[30]

The future of knee replacement market

               The value of world knee implants market in 2011 was estimated at US 8.4 billion and it is projected to reach US 15 billion by the year 2018. European and United States between them account for seventy percent of the market for knee implants.[31]Therefore, the market for knee implants is projected grow due to factors such as technology, age, and sports injuries. According to

Frost & Sullivan, the rapid ageing of Europe’s residents affected with diseases such as osteoarthritis and rheumatoid arthritis will be an impetus for the manufacturing of more knee implants in

the near future accompanied with technology that enhances efficiency will led to the increase in

surgeries for the younger population.[32]

Additionally, advancement in technology that has made knee replacement surgery much safer will continues to push the market of knee implants and so more people will seek replacement surgery. The urgent need to diminish the number of patients waiting for knee replacement will aid in the increase of the market in knee implants.

               The emergence of revision surgery will also push the markets higher. Although, replacement has surgery has had a higher success rate, however, they has been an increase in revision joint replacements. In the last few years, it is estimated that the growth for revision implant products is between twelve percent and fifteen percent, which is more than twice the increase of the need for artificial implants over the same period.[33]

Additionally, the market value of this industry is also increased by the advancement in technology especially in the innovation and manufacture of novel materials, efficiency in surgery procedures, new products and their design. New manufacturing methods such as Computer aided design (CAD), novel materials that are used as alternatives to bones, new joint replacement techniques which aid in improvement of performance are contributors to profitability of this venture especially in Europe.[34]

In the future the market value of the implants will be through the elimination of the use of local intermediaries such as distributors to direct supply the market by the parent companies or by their subsidiaries. This will reduce costs at the same time maximizing profits. Additionally, it will lead to direct contact with the customer ensuring effective response to clients.

In developing countries such as India there has been continuous growth in the knee prosthetic business. For example, since 2012 there has been an increase in the market value for knee implants. This has been made possible through the high volume of implants being sold although price per the unit is lower compared to Europe and United States.[35] However, European and American companies that deal with the manufacturing of knee replacement implants still continue to dominate the Asian market, especially targeting the high income earners in this countries and working in collaboration with affluent hospitals and clinic in the respective countries.  

The future markets for implants is bright in Asia due to the increase in demand for knee replacement implants as a result of Asians increase in wealth and age. The Asian market accounts for a quarter of the world’s 41 billion dollars prosthetic market. The decrease in birth rates coupled with increase in income in Asian countries such as Singapore, Hong Kong and even India has made medical procedures which were out of reach for these populations a few years ago now affordable.

Therefore, it projected that foreign companies will have abundant opportunities in the Asian knee replacement implants market in the future as growth in developing countries such as India and China increases and lower returns in Europe and the US. However, these companies will have to contend with stiff competition from domestic manufacturers in these countries who produces cheaper implants.

In conclusion, this review discussed advances in knee replacement surgeries and compared the different techniques and implants used. Additionally, it compared the market for knee implants globally especially between developed and developing countries. It found that even in developing countries the market is still dominated by European and American companies such as Zimmer, DePuy synthes, Stryker and Smith & Nephew. However, these companies are facing stiff competition from local companies which have favorable working conditions due to local government policies and regulations. The European and American knee replacement markets are dominated by Zimmer, Zimmer, DePuy synthes Stryker and Smith & Nephew which are the most successful companies. These aforementioned companies themselves or through their subsidiaries dominate the market in Europe. Knee replacement implants and surgery is cheaper in Europe when compared to the US due to government regulations in European countries unlike in the US where manufacturing companies have formed cartels and charge exorbitant prices. The future of the knee replacement market is bright in Europe, US and in developing countries such as China and India due age and increase in wealth of these populations (China and India). 


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[1] Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[2]Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[3]Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[4]Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,



[7]Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[8] BoneSmart, “Knee Implants,” accessed November 3, 2014, htt://



[11]BoneSmart, “Knee Implants,” accessed November 3, 2014, htt://

[12] Ibid

[13] Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[14] Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[15] Ibid

[16] Ibid

[17] Samuel Greengard, “Knee Replacement: Your Surgical Options,” Healthline, April 30, 2012, accessed on November 4, 2014,

[18] Ibid

[19]Elizabeth Rosenthal, “In Need of a New Hip, but Priced Out of the U.S.,” New York Times, August 3, 2013, accessed November 3, 2014,


[21]Elizabeth Rosenthal, “In Need of a New Hip, but Priced Out of the U.S.,” New York Times, August 3, 2013, accessed November 3, 2014,

[22] Drugwatch, “Zimmer Knee Replacements,” accessed November 4, 2014,


[24] Jamie Hartford, “Homegrown Orthopedic Joint Makers Gain Marketshare in Asia,” Orthopedics, March 27, 2013, accessed November 8, 2014.

            [25] BusinesStandard, Maxx Medical aims Top 3 slot in knee replacement systems,” accessed November 8, 2014.

[26] Jamie Hartford, “Homegrown Orthopedic Joint Makers Gain Marketshare in Asia,” Orthopedics, March 27, 2013, accessed November 8, 2014.

[27] Ibid.

[28] Jamie Hartford, “Homegrown Orthopedic Joint Makers Gain Marketshare in Asia,” Orthopedics, March 27, 2013, accessed November 8, 2014.

[29] Ames Gross, “Asian Orthopedics Markets,” Pacific Bridge Medical, June 21, 2013, accessed on November 8, 2014,

[30] Ibid

[31] “Knee Implants Market-Global Industry Size, Share, Trends, Analysis And Forecasts 2012-2018,” Transparency Market Research, accessed November 3, 2014,

[32]“European Market for Hip and Knee Replacements,” PR Newswire, accessed November 3, 2014,



[35] MarketWatch, “MediPoint: Knee Replacement-current and Future Players,” accessed November 8, 2014,