{{Short description|Type of knee surgery}} {{Infobox medical intervention | name = Meniscus transplant | synonym =Meniscal transplant | image = | caption = | alt = | pronounce = | specialty = orthopedic | synonyms = | ICD10 = | ICD9 = | ICD9unlinked = | CPT = | MeshID = | LOINC = | other_codes = | MedlinePlus = | eMedicine = }} A '''meniscus transplant''' or '''meniscal transplant''' is a transplant of the meniscus of the knee, which separates the thigh bone (femur) from the lower leg bone (tibia). The worn or damaged meniscus is removed and is replaced with a new one from a donor. The meniscus to be transplanted is taken from a cadaver, and, as such, is known as an allograft. Meniscal transplantation is technically difficult, as it must be sized accurately for each person, positioned properly and secured to the tibial plateau.<ref name="twomey">{{cite journal |vauthors=Twomey-Kozak J, Jayasuriya CT |title=Meniscus Repair and Regeneration: A Systematic Review from a Basic and Translational Science Perspective |journal=Clinics in Sports Medicine |volume=39 |issue=1 |pages=125–163 |date=January 2020 |pmid=31767102 |pmc=6884076 |doi=10.1016/j.csm.2019.08.003}}</ref> Its success also depends on donor compatibility, stability of the transplant, and long-term health of the underlying articular cartilage.<ref name=twomey/>
==Background== Each knee has an inside (medial) and an outside (lateral) meniscus. The menisci play several key roles that are vital in maintaining the health of the knee.<ref name="swenson">{{cite journal|last=Swenson|first=TM|author2=Harner, CD|title=Knee ligament and meniscal injuries. Current concepts.|journal=The Orthopedic Clinics of North America|date=Jul 1995|volume=26|issue=3|pages=529–46|doi=10.1016/S0030-5898(20)32014-9|pmid=7609964}}</ref> Specifically, they act as shock absorbers and load sharers, increase the stability of the knee, and provide lubrication and nutrition to the bearing surface (articular cartilage) of the knee.<ref name="henning">{{cite journal|last=Henning|first=CE|author2=Lynch, MA|title=Current concepts of meniscal function and pathology.|journal=Clinics in Sports Medicine|date=Apr 1985|volume=4|issue=2|pages=259–65|doi=10.1016/S0278-5919(20)31233-3|pmid=3838702}}</ref><ref name="levy1">{{cite journal|last=Levy|first=IM|author2=Torzilli, PA |author3=Gould, JD |author4= Warren, RF |title=The effect of lateral meniscectomy on motion of the knee.|journal=The Journal of Bone and Joint Surgery. American Volume|date=Mar 1989|volume=71|issue=3|pages=401–6|pmid=2925713 |doi=10.2106/00004623-198971030-00014}}</ref><ref name="levy2">{{cite journal|last=Levy|first=IM|author2=Torzilli, PA |author3=Warren, RF |title=The effect of medial meniscectomy on anterior-posterior motion of the knee.|journal=The Journal of Bone and Joint Surgery. American Volume|date=Jul 1982|volume=64|issue=6|pages=883–8|pmid=6896333|doi=10.2106/00004623-198264060-00011}}</ref><ref name="seedhom">{{cite journal|last=Seedhom|first=BB|author2=Dowson, D |author3=Wright, V |title=Proceedings: Functions of the menisci. A preliminary study.|journal=Annals of the Rheumatic Diseases|date=Jan 1974|volume=33|issue=1|pages=111|pmid=4821376|pmc=1006215|doi=10.1136/ard.33.1.111}}</ref>
They were once thought of as vestigial structures that served no real purpose.<ref name="mcmurray">{{cite journal|last=McMurray|first=T. P.|title=The semilunar cartilages|journal=British Journal of Surgery|date=1 April 1942|volume=29|issue=116|pages=407–414|doi=10.1002/bjs.18002911612|s2cid=72803852}}</ref> If injured and problematic, they were routinely excised through a procedure called meniscectomy.<ref name="mcmurray" /> It is now known that a knee joint without healthy menisci is at significantly increased risk of developing wear and tear arthritis (post-traumatic or osteoarthritis).<ref name="wilson">{{cite journal|vauthors=Wilson W, van Rietbergen B, van Donkelaar CC, Huiskes R |title=Pathways of load-induced cartilage damage causing cartilage degeneration in the knee after meniscectomy.|journal=Journal of Biomechanics|date=Jun 2003|volume=36|issue=6|pages=845–51|pmid=12742452|doi=10.1016/s0021-9290(03)00004-6|title-link=cartilage}}</ref><ref name="pena">{{cite journal|last=Peña|first=E|author2=Calvo, B |author3=Martínez, MA |author4=Palanca, D |author5= Doblaré, M |title=Finite element analysis of the effect of meniscal tears and meniscectomies on human knee biomechanics.|journal=Clinical Biomechanics (Bristol, Avon)|date=Jun 2005|volume=20|issue=5|pages=498–507|pmid=15836937|doi=10.1016/j.clinbiomech.2005.01.009}}</ref> The arthritis is a result of the increased contact forces and shear that results from loss of shock absorption and stability after meniscectomy.<ref name="mcnicholas">{{cite journal|last=McNicholas|first=MJ|author2=Rowley, DI |author3=McGurty, D |author4=Adalberth, T |author5=Abdon, P |author6=Lindstrand, A |author7= Lohmander, LS |title=Total meniscectomy in adolescence. A thirty-year follow-up.|journal=The Journal of Bone and Joint Surgery. British Volume|date=Mar 2000|volume=82|issue=2|pages=217–21|pmid=10755429|doi=10.1302/0301-620x.82b2.0820217}}</ref><ref name="rockborn">{{cite journal|last=Rockborn|first=P|author2=Messner, K|title=Long-term results of meniscus repair and meniscectomy: a 13-year functional and radiographic follow-up study.|journal=Knee Surgery, Sports Traumatology, Arthroscopy|year=2000|volume=8|issue=1|pages=2–10|pmid=10663312|doi=10.1007/s001670050002|s2cid=24847895}}</ref><ref name="roos1">{{cite journal|last=Roos|first=H|author2=Laurén, M |author3=Adalberth, T |author4=Roos, EM |author5=Jonsson, K |author6= Lohmander, LS |title=Knee osteoarthritis after meniscectomy: prevalence of radiographic changes after twenty-one years, compared with matched controls.|journal=Arthritis and Rheumatism|date=Apr 1998|volume=41|issue=4|pages=687–93|pmid=9550478|doi=10.1002/1529-0131(199804)41:4<687::AID-ART16>3.0.CO;2-2}}</ref><ref name="roos2">{{cite journal|last=Roos|first=EM|author2=Ostenberg, A |author3=Roos, H |author4=Ekdahl, C |author5= Lohmander, LS |title=Long-term outcome of meniscectomy: symptoms, function, and performance tests in patients with or without radiographic osteoarthritis compared to matched controls.|journal=Osteoarthritis and Cartilage|date=May 2001|volume=9|issue=4|pages=316–24|pmid=11399095|doi=10.1053/joca.2000.0391|doi-access=free}}</ref> For this reason, current surgical strategies are focused on preserving as much of the meniscus as possible or replacing it if necessary.<ref name="lee">{{cite journal|last=Lee|first=SJ|author2=Aadalen, KJ |author3=Malaviya, P |author4=Lorenz, EP |author5=Hayden, JK |author6=Farr, J |author7=Kang, RW |author8= Cole, BJ |title=Tibiofemoral contact mechanics after serial medial meniscectomies in the human cadaveric knee.|journal=The American Journal of Sports Medicine|date=Aug 2006|volume=34|issue=8|pages=1334–44|pmid=16636354|doi=10.1177/0363546506286786|s2cid=26404505}}</ref>
Certain meniscal tears are repairable with sutures, predominantly those that are freshly torn and involve healthy tissue.<ref name="venkatachalam">{{cite journal|last=Venkatachalam|first=S|author2=Godsiff, SP |author3=Harding, ML |title=Review of the clinical results of arthroscopic meniscal repair.|journal=The Knee|date=Jun 2001|volume=8|issue=2|pages=129–33|pmid=11337239|doi=10.1016/s0968-0160(01)00061-8}}</ref> The closer the tear is to the peripheral blood supply the higher the likelihood of successful repair.<ref name="venkatachalam" /><ref name="arnoczky">{{cite journal|last=Arnoczky|first=SP|author2=Warren, RF|title=The microvasculature of the meniscus and its response to injury. An experimental study in the dog.|journal=The American Journal of Sports Medicine|date=May–Jun 1983|volume=11|issue=3|pages=131–41|pmid=6688156|doi=10.1177/036354658301100305|s2cid=36627496}}</ref> Patients with unrepairable meniscal injuries usually have symptoms of pain, catching, swelling or locking in the knee.<ref name="mcdermott">{{cite journal|last=McDermott|first=I|title=Meniscal tears, repairs and replacement: their relevance to osteoarthritis of the knee.|journal=British Journal of Sports Medicine|date=Apr 2011|volume=45|issue=4|pages=292–7|pmid=21297172|doi=10.1136/bjsm.2010.081257|s2cid=1234837}}</ref> The surgeon may perform a partial or complete meniscectomy to alleviate the symptoms in the short-term.<ref name="mcdermott" /> The more meniscal tissue removed, the higher the likelihood of subsequently developing arthritis.<ref name = "pena" /> Recognizing the biomechanical importance of the menisci, surgeons in the late 1980s proposed meniscus transplantation and meniscus reconstruction as two new surgical options for the patient with a meniscus deficient knee.<ref name="milachowski">{{cite journal|last=Milachowski|first=KA|author2=Weismeier, K |author3=Wirth, CJ |title=Homologous meniscus transplantation. Experimental and clinical results.|journal=International Orthopaedics|year=1989|volume=13|issue=1|pages=1–11|pmid=2722311|doi=10.1007/bf00266715|s2cid=21438778}}</ref><ref name = "stone1">{{cite journal|last=Stone|first=KR|author2=Steadman, JR |author3=Rodkey, WG |author4= Li, ST |title=Regeneration of meniscal cartilage with use of a collagen scaffold. Analysis of preliminary data.|journal=The Journal of Bone and Joint Surgery. American Volume|date=Dec 1997|volume=79|issue=12|pages=1770–7|pmid=9409790 |doi=10.2106/00004623-199712000-00002|citeseerx=10.1.1.1016.5479|s2cid=23551862}}</ref><ref name="stone2">{{cite journal|last=Stone|first=KR|author2=Rodkey, WG |author3=Webber, RJ |author4=McKinney, L |author5= Steadman, JR |title=Future directions. Collagen-based prostheses for meniscal regeneration.|journal=Clinical Orthopaedics and Related Research|date=Mar 1990|issue=252|pages=129–35|pmid=2406067 |doi=10.1097/00003086-199003000-00018}}</ref>
Recognizing from experiments performed by R.J. Webber, PhD<ref name="webber">{{cite journal|last=Webber|first=RJ|author2=York, JL |author3=Vanderschilden, JL |author4= Hough AJ, Jr |title=An organ culture model for assaying wound repair of the fibrocartilaginous knee joint meniscus.|journal=The American Journal of Sports Medicine|date=May–Jun 1989|volume=17|issue=3|pages=393–400|pmid=2729490|doi=10.1177/036354658901700314|s2cid=6787273}}</ref> that meniscus cells have the ability to grow in tissue culture, K.R. Stone, M.D. developed the first meniscus reconstruction device called a collagen regeneration template in 1986.<ref name = "stone2" /> The template or scaffold was composed of glycosaminoglycan (sugar/proteins that make up cartilage tissue) and was designed to have pores into which cells could grow. Its cross-linking preserved the scaffold in the knee joint long enough for new meniscus tissue to grow into it.<ref name = "stone2" /> (Patents 5,158,574, 5,116,374, 5,007,934) This scaffold was tested in animals and subsequently in people and was found to successfully replace lost segments of meniscus tissue<ref name="stone1" /><ref name="stone2" /><ref name="stone3">{{cite journal|last=Stone|first=KR|title=Meniscus replacement.|journal=Clinics in Sports Medicine|date=Jul 1996|volume=15|issue=3|pages=557–71|doi=10.1016/S0278-5919(20)30112-5|pmid=8800536}}</ref> (Fig 1). It became widely available in Europe and temporarily in the US in 2009. However, in cases where large areas of meniscus are missing, full intact meniscus transplantation has been suggested.<ref name="stone3" /><ref name="kuhn">{{cite journal|last=Kuhn|first=JE|author2=Wojtys, EM|title=Allograft meniscus transplantation.|journal=Clinics in Sports Medicine|date=Jul 1996|volume=15|issue=3|pages=537–6|doi=10.1016/S0278-5919(20)30111-3|pmid=8800535}}</ref>
==Indications for meniscus transplantation== Most people who are meniscus deficient already have some arthritic changes in their knee.<ref name="stone4">{{cite journal|last=Stone|first=KR|author2=Adelson, WS |author3=Pelsis, JR |author4=Walgenbach, AW |author5= Turek, TJ |title=Long-term survival of concurrent meniscus allograft transplantation and repair of the articular cartilage: a prospective two- to 12-year follow-up report.|journal=The Journal of Bone and Joint Surgery. British Volume|date=Jul 2010|volume=92|issue=7|pages=941–8|pmid=20595111|doi=10.1302/0301-620X.92B7.23182|s2cid=11758400|doi-access=free}}</ref> Early reports of meniscus transplantation done in arthritic knees suggested a higher incidence of transplantation failure if the irregular cartilage surfaces were not simultaneously addressed with cartilage grafting techniques.<ref name = "cameron">{{cite journal|last=Cameron|first=JC|author2=Saha, S|title=Meniscal allograft transplantation for unicompartmental arthritis of the knee.|journal=Clinical Orthopaedics and Related Research|volume=337|date=Apr 1997|issue=337|pages=164–71|pmid=9137187|doi=10.1097/00003086-199704000-00018|s2cid=36984788}}</ref><ref name="noyes2">{{cite journal|last=Noyes|first=FR|author2=Barber-Westin, SD|title=Meniscus transplantation: indications, techniques, clinical outcomes.|journal=Instructional Course Lectures|year=2005|volume=54|pages=341–53|pmid=15948463}}</ref> Therefore, the standard orthopaedic literature recommended that meniscus transplantation be performed in meniscus deficient patients only if they are young and free from arthritis of the knee.<ref name="noyes2"/><ref name="verdonk">{{cite journal|last=Verdonk|first=R|author2=Almqvist, KF |author3=Huysse, W |author4= Verdonk, PC |title=Meniscal allografts: indications and outcomes.|journal=Sports Medicine and Arthroscopy Review|date=Sep 2007|volume=15|issue=3|pages=121–5|pmid=17700371|doi=10.1097/JSA.0b013e318140002c|s2cid=2425860}}</ref><ref name="cole">{{cite journal|last=Cole|first=BJ|author2=Carter, TR |author3=Rodeo, SA |title=Allograft meniscal transplantation: background, techniques, and results.|journal=Instructional Course Lectures|year=2003|volume=52|pages=383–96|pmid=12690865}}</ref><ref name = "friel">{{cite journal|last=Friel|first=Nicole A.|author2=Cole, Brian J.|title=Sports Medicine|journal=Current Orthopaedic Practice|date=1 January 2010|volume=21|issue=1|pages=22–26|doi=10.1097/BCO.0b013e3181c78f8d|s2cid=75849935}}</ref> The most recently published indications for meniscal transplantation include:<ref name="noyes2"/> * Prior meniscectomy * Age ≤ 50 years * Pain in the meniscectomized tibiofemoral compartment * No radiographic evidence of advanced joint deterioration * ≥ 2mm of tibiofemoral joint space on 45 degrees weight-bearing posteroanterior radiographs * No or only minimal bone exposed on tibiofemoral surfaces * Normal axial alignment
In the same textbook, contraindications are listed as: * Advanced knee joint arthrosis (flattening of the femoral condyle, concavity of the tibial plateau, osteophytes that prevent anatomic seating of the meniscus transplant) * Uncorrected varus or valgus axial malalignment * Uncorrected knee joint instability * Anterior cruciate ligament deficiency * Knee arthrofibrosis * Significant muscular atrophy * Prior joint infection with subsequent arthrosis * Symptomatic noteworthy patellofemoral articular cartilage deterioration * Obesity (body mass index > 30) * Prophylactic procedure (asymptomatic patient with no articular cartilage damage)
===Debate of indications=== Many orthopaedists have challenged these contraindications and have advocated meniscal transplantation, in conjunction with cartilage repair, ACL reconstruction or osteotomy in patients with evidence of arthritic deterioration, instability or malalignment.<ref name="milachowski" /><ref name="stone4" /> One paper demonstrated that results of meniscus transplantation in patients with arthritic changes were similar to that of previous reports of meniscus transplantation in patients without arthritic changes, so long as articular cartilage defects were addressed at the time of surgery.<ref name="stone4" /> In the same paper, the success of meniscus transplantation was not affected by mal-alignment.<ref name="stone4" />
==Meniscus transplant preparations==
===Meniscus tissue processing=== Meniscal allograft processing, sterilization and storage procedures vary from center to center.<ref name="mcdermott2">{{cite journal|last=McDermott|first=ID|title=What tissue bankers should know about the use of allograft meniscus in orthopaedics.|journal=Cell and Tissue Banking|date=Feb 2010|volume=11|issue=1|pages=75–85|pmid=19387868|doi=10.1007/s10561-009-9127-2|s2cid=23882232}}</ref> Some surgeons, particularly in Europe, prefer to harvest the meniscal graft themselves in a sterile fashion and use them when they are fresh, usually within two weeks of procurement.<ref name="mcdermott2" /> On the other hand, some American centers harvest the graft outside of a sterile operating room environment and then perform a sterilization wash.<ref name="mcdermott2" /> These grafts are then packaged and frozen at -80 °C, until they are to be transplanted. To decrease the risk of disease transmission, irradiating the graft has been used in the past to enhance sterilization.<ref name="mcdermott2" /> However, it has been shown to degrade most collagen-based tissues and the meniscus is particularly susceptible.<ref name="cheung">{{cite journal|last=Cheung|first=DT|author2=Perelman, N |author3=Tong, D |author4= Nimni, ME |title=The effect of gamma-irradiation on collagen molecules, isolated alpha-chains, and crosslinked native fibers.|journal=Journal of Biomedical Materials Research|date=May 1990|volume=24|issue=5|pages=581–9|pmid=2324128|doi=10.1002/jbm.820240505}}</ref> Tissue preservation techniques such as cryo-preservation and freeze-drying have shown little benefit and have generally been abandoned except by a few tissue banks.<ref name="mcdermott2" />
===Meniscus tissue sizing=== Matching the size of the donor knee to the size of the recipient knee is crucial for successful meniscus transplantation.<ref name="sekaran">{{cite journal|last=Sekaran|first=SV|author2=Hull, ML |author3=Howell, SM |title=Nonanatomic location of the posterior horn of a medial meniscal autograft implanted in a cadaveric knee adversely affects the pressure distribution on the tibial plateau.|journal=The American Journal of Sports Medicine|date=Jan–Feb 2002|volume=30|issue=1|pages=74–82|pmid=11799000|doi=10.1177/03635465020300012601|s2cid=3900315}}</ref><ref name="dienst">{{cite journal|last=Dienst|first=M|author2=Greis, PE |author3=Ellis, BJ |author4=Bachus, KN |author5= Burks, RT |title=Effect of lateral meniscal allograft sizing on contact mechanics of the lateral tibial plateau: an experimental study in human cadaveric knee joints.|journal=The American Journal of Sports Medicine|date=Jan 2007|volume=35|issue=1|pages=34–42|pmid=16923825|doi=10.1177/0363546506291404|s2cid=1238880}}</ref> Studies by Pollard et al. noted the radiographic (x-ray) measurements provided an indication of meniscus size based on the width of the tibial plateau.<ref>{{cite journal|last=Pollard|first=ME|author2=Kang, Q |author3=Berg, EE |title=Radiographic sizing for meniscal transplantation.|journal=Arthroscopy|date=Dec 1995|volume=11|issue=6|pages=684–7|pmid=8679029|doi=10.1016/0749-8063(95)90110-8}}</ref> However, inherent variability in both the positioning of the knee and the direction of the x-ray beam, as well as human error contribute to some inaccuracy of these measurements. Sizing has been made more accurate with the use of MRI.<ref name="haut">{{cite journal|last=Haut|first=TL|author2=Hull, ML |author3=Howell, SM |title=Use of roentgenography and magnetic resonance imaging to predict meniscal geometry determined with a three-dimensional coordinate digitizing system.|journal=Journal of Orthopaedic Research|date=Mar 2000|volume=18|issue=2|pages=228–37|pmid=10815823|doi=10.1002/jor.1100180210|s2cid=3889006}}</ref> Matching by sex, height, and weight has been shown to be nearly as accurate as radiographic techniques (0.72 correlation of height to tibial width) and has been adopted by a number of centers.<ref name="stone5">{{cite journal|last=Stone|first=KR|author2=Freyer, A |author3=Turek, T |author4=Walgenbach, AW |author5=Wadhwa, S |author6= Crues, J |title=Meniscal sizing based on gender, height, and weight.|journal=Arthroscopy|date=May 2007|volume=23|issue=5|pages=503–8|pmid=17478281|doi=10.1016/j.arthro.2006.12.025}}</ref>
==Surgical technique== Various meniscal transplant techniques have been described, all of which are considered surgically demanding.<ref name="mcdermott2" /> All involve arthroscopy and some require open surgery, as well. Some surgeons leave the allograft anchored to its bony attachments and fix these bone bridges or plugs into size matched slots, troughs or holes.<ref name="friel" /><ref name="noyes3">{{cite journal|last=Noyes|first=FR|author2=Heckmann, TP |author3=Barber-Westin, SD |title=Meniscus repair and transplantation: a comprehensive update.|journal=The Journal of Orthopaedic and Sports Physical Therapy|date=Mar 2012|volume=42|issue=3|pages=274–90|pmid=21891878|doi=10.2519/jospt.2012.3588|doi-access=free}}</ref><ref name="lee2">{{cite journal|last=Lee|first=AS|author2=Kang, RW |author3=Kroin, E |author4=Verma, NN |author5= Cole, BJ |title=Allograft meniscus transplantation.|journal=Sports Medicine and Arthroscopy Review|date=Jun 2012|volume=20|issue=2|pages=106–14|pmid=22555208|doi=10.1097/JSA.0b013e318246f005|s2cid=27719328}}</ref> Other surgeons use tunnels through which they pass sutures that hold the allograft in place.<ref name="stone4" /><ref>{{cite journal|last=Verdonk|first=PC|author2=Demurie, A |author3=Almqvist, KF |author4=Veys, EM |author5=Verbruggen, G |author6= Verdonk, R |title=Transplantation of viable meniscal allograft. Surgical technique.|journal=The Journal of Bone and Joint Surgery. American Volume|date=Mar 2006|volume=88 Suppl 1 Pt 1|pages=109–18|pmid=16510805|doi=10.2106/JBJS.E.00875|hdl=1854/LU-384762|url=https://biblio.ugent.be/publication/384762|hdl-access=free}}</ref> Additional sutures are also used to attach the allograft to the remnant of native meniscus.<ref name="noyes3" /> Important points include obtaining stable and anatomic fixation of the horns of the meniscus and securing the meniscus rim to the tibia. Securing the graft in this way preserves the hoop (concentric) stresses of the meniscus.<ref name="stone6">{{cite journal|last=Stone|first=KR|author2=Walgenbach, AW|title=Meniscal allografting: the three-tunnel technique.|journal=Arthroscopy|date=Apr 2003|volume=19|issue=4|pages=426–30|pmid=12671626|doi=10.1053/jars.2003.50133}}</ref><ref name = "jones">{{cite journal|last=Jones|first=RS|author2=Keene, GC |author3=Learmonth, DJ |author4=Bickerstaff, D |author5=Nawana, NS |author6=Costi, JJ |author7= Pearcy, MJ |title=Direct measurement of hoop strains in the intact and torn human medial meniscus.|journal=Clinical Biomechanics (Bristol, Avon)|date=Jul 1996|volume=11|issue=5|pages=295–300|pmid=11415635|doi=10.1016/0268-0033(96)00003-4}}</ref> Meniscus extrusion or shrinking has been noted and may be in part a function of sewing the meniscus too tightly to the synovium rather than restoring the meniscus tibial ligamentous attachments.<ref name="stone6" /><ref name=alhalki>{{cite journal|last=Alhalki|first=MM|author2=Howell, SM |author3=Hull, ML |title=How three methods for fixing a medial meniscal autograft affect tibial contact mechanics.|journal=The American Journal of Sports Medicine|date=May–Jun 1999|volume=27|issue=3|pages=320–8|pmid=10352767|doi=10.1177/03635465990270030901|s2cid=3951812}}</ref>
==Post-op meniscus transplantation programs== Post-operatively, meniscus transplant patients enter specific rehabilitation programs, aimed at decreasing pain and swelling, optimizing range of motion and strength, while avoiding injury to the healing meniscal allograft.<ref name="noyes3" /> Most patients are allowed partial weight bearing in extension immediately as it stabilizes the meniscus on the surface of the tibia.<ref name = "noyes3" />
==Results== Multiple articles report the results of meniscal transplantation.<ref name="hergan">{{cite journal|last=Hergan|first=D|author2=Thut, D |author3=Sherman, O |author4= Day, MS |title=Meniscal allograft transplantation.|journal=Arthroscopy|date=Jan 2011|volume=27|issue=1|pages=101–12|pmid=20884166|doi=10.1016/j.arthro.2010.05.019}}</ref> Unfortunately, because these studies are mainly uncontrolled, retrospective case series, drawing conclusions regarding meniscal transplantation is difficult.<ref name="hergan" /> No study has compared meniscus deficient patients who received meniscal transplantation with those who did not.<ref name="hergan" /> Designing and conducting a study in this way is difficult.<ref name="hergan" /> A recent systematic review of the literature determined that “good early and midterm results of cryo-preserved or fresh-frozen, non-irradiated meniscal allograft transplantation can be achieved in a relatively young patient with only mild chondromalacia (lower than Outerbridge grade 3) [cartilage degeneration] who is not overweight and has a stable, mechanically aligned lower extremity, if the allograft is sized radiographically by use of anteroposterior and lateral films and the allograft meniscal horns have bony attachments and are fixed by bony techniques..."<ref name="hergan" /> However, Stone et al. published long-term results of meniscus transplantation with simultaneous repair of the articular cartilage and demonstrated a mean estimated procedure survival time of 9.9 years. Significant improvements in pain relief, activity, and function were found over the course of follow-up indicating patients improve significantly within the first two years after surgery and that these improvements are maintained over time.<ref name="stone4" />
==Controversies== There is a lack of consensus between surgeons in key areas of meniscal transplantation.<ref name="mcdermott2" /><ref name="hergan" /> Questions remain concerning indications, long-term efficacy, as well as allograft sizing, processing and fixation techniques.<ref name=twomey/><ref name = "hergan" /> Most surgeons, however, agree that meniscal transplantation seems to afford at least short- to medium-term benefit.<ref name="mcdermott" /><ref name="verdonk" /><ref name="noyes3" /><ref name="lee2" /><ref name="hergan" /><ref>{{cite journal|last=Anz|first=AW|author2=Rodkey, WG|title=Biological enhancement of meniscus repair and replacement.|journal=Sports Medicine and Arthroscopy Review|date=Jun 2012|volume=20|issue=2|pages=115–20|pmid=22555209|doi=10.1097/JSA.0b013e31824483e9|s2cid=42268920}}</ref>
Meniscal transplantation is a novel surgical technique designed to improve the biology and biomechanics of a meniscus deficient knee.<ref name=twomey/> Improvements in short-term and long-term subjective and objective outcome measures have been demonstrated.<ref name=twomey/>
==References== {{Reflist}}
==External links== * [https://www.medlineplus.gov/ency/article/007209.htm Procedure description] NIH
Category:Orthopedic surgical procedures