Knee prosthesis
A knee prosthesis , knee endoprosthesis or knee joint prosthesis is an implanted prosthesis ( endoprosthesis ) that completely or partially replaces the knee joint (as a TEP ). The knee prosthesis is mainly used in the event of severe wear and tear of the knee ( osteoarthritis of the knee ) and after injuries to the knee as surgical therapy in order to restore pain-free mobility and, if necessary, also the stability of the knee joint in the case of ligament instability. Partial or total endoprostheses can be used. After the hip joint prosthesis, the knee prosthesis is the second most frequently used joint endoprosthesis with around 175,000 first operations per year throughout Germany (first implantations 2009).
This article does not deal with the external knee prosthesis or the prosthetic knee after amputations above the knee joint.
Indications and contraindications
The use of a knee prosthesis may be necessary for:
- degenerative osteoarthritis (damage to the joint cartilage)
- rheumatoid arthritis (inflammation of the joint causing cartilage damage)
- post-traumatic arthritis (post-accident arthritis)
- symptomatic knee instability (injuries to the ligamentous apparatus)
- Knee stiffening (reconstruction of the mobility of the joint)
- Deformation of the knee joint
- Reconstruction of a knee joint function after resections as part of tumor surgery
Depending on the disease and its severity, the doctor has to choose the best possible solution and therapy for the patient from the different types of implants. The correct indication is solely the responsibility of the attending physician. The affected patients should also be included in the decision-making process so that the doctor and patient can exchange information about the patient's ideas and needs, the processes and expected surgical results. In this way, these factors can be taken into account when establishing the indication.
A knee prosthesis should not be used if a reconstructive procedure (e.g. osteotomy ) is possible to treat the joint disease , if there are acute or chronic infections in or near the joint, or systemic infections. Contraindications are also disorders in the bone itself, such as metabolic disorders , osteoporosis or osteomalacia , damage to the bone structure that prevent stable anchoring of the implant or bone tumors in the area of the implant anchoring . The knee prosthesis can hardly be used with bony deformities or extreme misalignments. A possible or proven metal allergy or intolerance is also a contraindication. An expected overloading of the implant, for example due to obesity (overweight), is considered a risk constellation; likewise drug, drug or alcohol addiction .
Classification of knee prostheses
Knee prostheses are classified according to their degree of coupling. This means that the more functionality of the natural ligamentous apparatus in the knee joint is damaged and has to be taken over by the knee prosthesis, the higher the degree of coupling. The knee joint is a so-called roll-slide joint. During normal gait, the lower leg rotates around the femur and slides forward. The knee kinematics are therefore very complex.
When moving from flexion to extension (from the bent to the extended knee), the lower leg rotates forward around the thigh. The foot and thus the lower leg rotates around the medial (inner) condyle outwards. When moving from extension to flexion, the lower leg rotates backwards around the thigh. The foot turns inwards and the lower leg slides forward. This complex kinematics comes about through the shape of the joint surfaces, the menisci and, above all, the arrangement of the ligaments and muscles .
The so-called uniknie (unicondylar (syn. Monocondylar) sledge prosthesis) is used when all ligaments on the knee joint are fully functional and the articular cartilage is only damaged in one of the two condyles. While the component femoral uniform consists of a metal alloy, there are three different basic types tibially: pure polyethylene components (so-called all-poly, e.g. Genesis, Journey, Mod I, St. Georg, UC plus), fixed PE components with Metal base (so-called metal-backed, e.g. Genesis, Journey, Mod II, UC Plus) or analog versions with mobile PE components (e.g. Oxford, LCS uni). A bicondylar primary prosthesis can be used if at least two of the three joint sections (inner or outer compartment as well as the kneecap with plain bearing) and possibly also the anterior cruciate ligament are damaged, but the other ligaments are sufficiently functional. The articular surfaces are replaced on both the femur and the shin . The menisci are removed. There are also individual implant systems that can be used even if the anterior cruciate ligament is intact.
If neither the anterior nor the posterior cruciate ligament is preserved, a so-called posterior stabilized prosthesis (PS knee) is used. Here the knee prosthesis already takes over the functions of the cruciate ligaments and forces the shinbone forwards with increasing flexion and the thighbone backwards. There are three methods for the rotary slide mechanism, each with a different design of the tibial component, while the femoral and patellar components remain the same:
- The tibial component consists exclusively of polyethylene, and this is placed directly on the prepared shin bone using bone cement ( all-polyethylene ).
- A polyethylene component is firmly attached to a metal component, which in turn is anchored in the shin either with or without cement ( modular metal backed or fixed bearing ).
- A polyethylene component is placed on a metal component in such a way that it can move within a specified framework against the metal component, which is primarily a sliding mechanism when the knee is bent ( rotating platform , or mobile bearing ). The metal component is in turn cemented or fixed in the prepared tibial bone without cement.
A prospective randomized study compared these three components from one manufacturer with the same femur and patella components. The surgeons were very experienced and equally familiar with all three tibial components, and found no significant results in 75–76 patients per group after two and five years can still prove clinical differences in terms of mobility, strength, function and satisfaction. With a total of only four revisions, this study does not yet allow any statements about the long-term stability.
If both the cruciate ligaments and the collateral ligaments are damaged, but the joint capsule and the muscular system are still intact, a so-called axis - guided rotation prosthesis (rotating hinge ) can be used. Here the implant takes over the stabilization of the joint both forwards and backwards as well as to the left and right. However, it allows the tibia to rotate against the femur, that is, the foot can still be turned outwards.
The axially guided knee is the last option . If the capsule and the muscular apparatus are also damaged, which is often associated with large bone defects, the rotation of the tibia against the femur, i.e. the turning of the foot, must be restricted and the knee joint stabilized. Here only the tibia can be moved forwards and backwards against the femur.
Historical
The first implantation of hinge joints was carried out in 1890 by the Berlin surgeon Themistocles Gluck : A simple ivory hinge was implanted in three patients with joint destruction due to tuberculosis , and they were fixed with nickel-plated screws and rosin, a resin. The attempts failed due to infections. Another attempt was made by Judet in 1947 with an acrylic resin prosthesis. The first hinge prosthesis that was successfully implanted in large numbers of cases was the Walldius model from 1951, which was subsequently modified several times. Other well-known early forms of the hinge prosthesis were the models by Shiers from 1953, Engelbrecht from 1970, Groupe Guepar from 1970, Sheehan from 1971, Blauth from 1972 and Gschwend-Schleier-Bähler (GSB) from 1972.
An isolated replacement of the femoral condyles took place in individual cases through developments by Campbell from 1940, Smith-Petersen from 1942 and Rocher from 1952. Larger case numbers are known for the models from Aufranc-Jones-Kermond from 1953 and Platt-Pepler from 1955.
The isolated tibial replacement took place in the first models from Marquard from 1951, McKeever from 1952 and McIntosh from 1956.
The first sliding surface replacement prostheses, i.e. the replacement of the femoral and tibial sliding surfaces medially and / or laterally without mechanical coupling, came from Gunston from 1968 (femoral steel, tibial polyethylene) and from Engelbrecht (St. Georg model) from 1969 (femoral steel, cobalt chrome molybdenum, tibial polyethylene), Freeman / Swanson from 1970 and marble from 1975.
Materials used
The most frequently used material is the cobalt-chrome cast alloy CoCr29Mo according to ISO 5832-4 for the femoral and tibial implant components . A cobalt-chromium alloy according to ISO 5832-12 is often used for augmentation wedges and plates . Titanium alloys or surface coatings made of zirconium nitride , titanium nitride or titanium niobium nitride are also used, which are especially suitable for patients with metal allergies such as B. Nickel allergy can be used. In the case of titanium alloys, the titanium on the articulating surfaces is treated with a special surface hardening process with nitrogen ions due to its low abrasion resistance. The surface coatings are vapor-deposited using the PVD process . The inlays (meniscus replacement) are usually made of UHMWPE (ultra high molecular weight polyethylene ) according to ISO 5834-2.
Anchoring and loading of the implant
Implants are usually anchored to the bone with bone cement . An anchorage without bone cement can also be chosen as an option. The implant components are then usually provided with a coating which has a particularly porous and therefore large surface, which promotes the growth of the bone and thus ensures secure anchoring. Until the bone has grown into this layer, the implant holds thanks to the so-called press fit. This means that the implant bed in the bone is prepared in such a way that the prosthesis clamps firmly in the bone.
In order to stabilize the body, considerable muscle forces act in the knee joint, which in addition to the body weight compress the joint and thus stress it. These forces can be approximately calculated with mathematical models or measured directly with instrumented measuring prostheses. For example, researchers at the Julius Wolff Institute at the Berlin Charité have developed an instrumented knee prosthesis to measure stress and used it on several patients. The measurement data are transmitted wirelessly to a computer. The results show that even when walking, a resulting force of around 2.5 times the body weight acts on the joint. When walking down the stairs, the resulting force increases up to 3.5 times the body weight.
Current developments
According to the 2019 annual report of the German Endoprosthesis Register (EPRD), cemented knee prostheses are usually used, only 2% are cement-free, and 5% hybrid, i.e. one component is cemented, the other is cement-free. The back of the kneecap has been replaced less and less frequently, currently only in 15% of cases. In contrast, the use of "posterior stabilized" (PS) total knee replacements has been increasing for years and currently reaches 23%. Movable polyethylene components ("mobile bearing") are also implanted less and less frequently, currently only in 16%. The proportion of unicondylar knee prostheses has increased over the years and is currently 12%. Particularly for unicondylar prostheses, there is a significantly better surgical result in clinics in which this procedure is performed very often compared to clinics that rarely perform the procedure.
Results
In a 2012 study by the Swedish Endoprosthesis Register, primary implantations of the complete knee joint (total endoprosthesis with and without kneecap replacement) showed ten-year survival rates of approx. 95% and for unicondylar sledge prostheses of approx. 85–90%. This means that statistically after ten years approx. 5% or 10–15% of the knee joints were removed or changed, while all other endoprostheses were not. However, neither the individual risk of switching nor the individual clinical and subjective individual result can be derived from this. The only target was the expansion or change. Reasons for changing a unicondylar sled prosthesis can include: B. the osteoarthritis of the previously untreated compartment with an intact prosthesis itself, conversely, an endoprosthesis that has not been replaced can in principle be due for replacement surgery, which, however, was not performed for other reasons.
Individual knee joint prostheses
In younger patients, prostheses made individually for the patient and his / her geometry are occasionally used. The dimensions required for this must first be determined using computer tomography . On the basis of the CT data, a virtual 3D model of the patient's knee is created on the computer , from which a template is made, a so-called negative mold, with the help of which the implant is made. The necessary surgical tools are also individually tailored to the patient's anatomy and manufactured using a 3D printing process . The surgical tool is used for the precise execution of the bone cuts and the positioning of the replacement joint. Correct positioning and alignment should contribute to the lowest possible bone consumption and a long service life for the prosthesis. This procedure can be used for both partial and total knee prostheses. In addition to the higher costs for the individual manufacture of the prosthesis, this procedure also results in a higher radiation exposure due to the computed tomography and a longer operating time. That the durability of the prosthesis can be extended has not yet been proven in the long term.
Risks and Complications
In principle, a distinction can be made between early complications in the first three to six months and late effects, as well as prosthesis-specific and general surgical complications.
The prosthesis-specific risks include, in particular, the possibility of the prosthesis loosening , which usually requires replacing the loosened prosthesis or all parts of the prosthesis, and the prosthesis infection from bacteria (and very rarely from mycosis ).
A typical early complication is deep vein thrombosis , which, despite prevention through early mobilization and prophylactic anticoagulation , can occur on both the operated and non-operated leg and can also trigger a pulmonary embolism .
General surgical risks are a superficial wound infection, wound healing disorder , seroma formation , persistent knee joint effusion and injuries to nearby nerves.
In a Danish overview of all initial implantations of a complete knee prosthesis carried out between 1997 and 2011 due to wear and tear, the risks in the first three months were calculated. The 32,754 prostheses were implanted in 63% in women and in 36% in men; 15% of the patients were over 80 years, in 77% regional anesthesia and in 20% general anesthesia . 78% of the prostheses were cemented, 8% were not cemented, and 14% were partially cemented hybrid prostheses. In 63% of the operations, the duration was 61–120 minutes. All patients received prophylactic anticoagulation. The 90 day risks were:
- 1.5% for a deep vein thrombosis (and already 1.1% in the first month), as risk factors an increased comorbidity , an operation time of 120 minutes and a hybrid anchorage were determined. Thus, despite anticoagulation, the risk of thrombosis was almost 3 times higher than that of bleeding.
- 0.4% for a heart attack (0.3% in the first month)
- 0.5% for an ischemic stroke (0.3% in the first month)
- 0.5% for heavy bleeding, especially in the gastrointestinal tract (0.3%) and rarely as cerebral haemorrhage (0.04%)
- 0.7% total for one death (0.3% in the first month)
In the event of serious complications, a thigh amputation may ultimately be inevitable. This risk was evaluated using data from the Danish national registries for all knee prostheses (92,785) implanted between 1997 and 2013 and is 0.32% (115 cases) after an average of 2.9 revisions after the first knee prosthesis. The main causes were uncontrollable periprosthetic infections (83% with multiple answers), soft tissue defects (23%), severe bone loss (18%), irreparable loss of the knee extensor apparatus and uncontrollable pain (11% each), periprosthetic bone fractures (9%) and vascular complications (8%) . Men were more often affected, as were patients who had received the knee prosthesis for post-traumatic osteoarthritis or rheumatoid arthritis .
Persistent pain after the procedure
The International Association for Pain Research defines persistent pain after surgery as lasting at least three months.
Studies have shown that up to 44% of all patients with a total knee replacement are affected by such pain.
Major manufacturers and brands
- Aesculap works : Columbus, Vega, Univation, e.motion
- Amplitude Surgical: Anatomic, Score, Score AS, Uni Score
- Baumer S / A: AKS (Anatomic Knee System)
- ConforMIS: iTotal, iUni, iDuo, iPoly
- Corin Group: Unity, Uniglide, HLS KneeTec
- DJO Global: EMPOWR
- Exactech: Truliant, Optetrak Logic
- Japan Medical Dynamic Marketing (JMDM) with Ortho Development Corporation: Balanced Knee, BKS TriMax
- Johnson & Johnson medical (DepuySynthes): LCS Complete, PFC Sigma, Attune
- Mathys AG : Balansys
- Medacta International: GMK Sphere, GMK Primary
- MicroPort Scientific Corporation (acquired from Wright Medical in 2014 ): Evolution, Advance
- Waldemar Link : Gemini
- Stryker Corporation : Duracon, Triathlon, Scorpio
- Smith & Nephew : Journey, Legion, Genesis II
- United Orthopedic Corporation (UOC): U2
- Zimmer Biomet Holdings : Vanguard, VanguardXP, NexGen, LPS flex, Persona
swell
- Ch. Lüring, H. Bäthis et al.: The navigation-assisted knee endoprosthetics: A position determination under evidence-based criteria. In: Dtsch Arztebl. 2005; 102 (34-35) (pdf)
- J. Jerosch, S. Fuchs, J. Heisel: Knee endoprosthetics - a location determination. In: Dtsch Arztebl. 1997; 94 (8) (pdf)
- H. Federau: The development of the knee endoprosthesis. Dissertation . Medical Faculty Munich, 1979.
- S. Grüner: Short and medium-term results of the alloarthroplastic treatment of the knee joint with uni- and bicondylar sled prostheses. Dissertation. Medical Faculty University of Cologne, 1992.
Web links
- Slide show about the implantation of a knee prosthesis ( Memento from April 19, 2015 in the Internet Archive )
- Instrumented knee prosthesis for in vivo measurement of forces and moments Julius Wolff Institute, Charité - Universitätsmedizin Berlin
- "OrthoLoad" Internet database with results of load measurements with knee prostheses (English)
- Endoprosthesis register: meeting the highest requirements
Individual evidence
- ↑ Barmer GEK: Barmer GEK Report Hospital 2010 - main topic: Trends in endoprosthetics of the hip and knee joint (PDF; 1.9 MB). 2011, p. 9.
- ↑ MM Kalisvaart, MW Pagnano, RT Trousdale, MJ Stuart, AD Hanssen: Randomized clinical trial of rotating-platform and fixed-bearing total knee arthroplasty: no clinically detecatable differences at five years. In: The Journal of Bone and Joint Surgery. American volume. Volume 94, Number 6, March 21, 2012, pp. 481-489, ISSN 0021-9355 . doi: 10.2106 / JBJS.K.00315 .
- ↑ bjj.boneandjoint.org.uk
- ↑ Endoprosthesis Register Germany (EPRD): Annual Report 2019, [1]
- ↑ Vera Zylka-Menhorn: Endoprothetik: Active role of the patient asked Deutsches Ärzteblatt 2020, Volume 117, Issue 9 of February 28, 2020, Page A-438 / B-382 / C-369, Link
- ↑ knee.nko.se ( Memento from November 26, 2013 in the Internet Archive )
- ↑ AB Pedersen, F. Mehnert, HT Sorensen, C. Emmeluth, S. Overgaard, SP Johnson: The risk of venous thromboembolism, myocardial infarction, stroke, major bleeding and death in patients undergoing total hip and knee replacement. In: The Bone & Joint Journal . 2014; Volume 96-B, Issue 4, April 2014, pp. 479-485. doi: 10.1302 / 0301-620X.96B4.33209
- ↑ Tinne B. Gottfriedson, Henrik M. Schrøder, Anders Odgaard: Transfermoral amputation after failure of knee arthroplasty . The Journal of Bone & Joint Surgery 2016, Volume 98-A, Issue 23, December 7, 2016, pp. 1962-1969; DOI: 10.2106 / JBJS.15.01362
- ↑ Wylde V, Hewlett S, Learmonth ID, Dieppe P. Persistent pain after joint replacement: prevalence, sensory qualities, and postoperative determinants. Pain. 2011
- ↑ IASP. Classification of chronic pain. Pain 1986; S1-226.
- ^ Baker PN, van der Meulen JH, et al .: The role of pain and function in determining patient satisfaction after total knee replacement: data from the National Joint Registry for England and Wales. J Bone Joint Surg Br 2007; 89B: 893-900. PMID 17673581 . doi : 10.1302 / 0301-620X.89B7.19091
- ↑ Brander VA, Stulberg SD, et al .: Predicting total knee replacement pain: a prospective, observational study. Clin Orthop Relat Res 2003; 416: 27-36.
- ↑ Puolakka PA, Rorarius MG, et al .: Persistent pain following knee arthroplasty. Eur J Anaesthesiol 2010; 27: 455-60. PMID 14646737 . doi : 10.1097 / 01.blo.0000092983.12414.e9
- ^ Wylde V, Blom AW, et al .: Patient-reported outcomes after total hip and knee arthroplasty: comparison of midterm results. J Arthroplasty 2009; 24: 210-6. PMID 18534427 . doi : 10.1016 / j.arth.2007.12.001
