The rehabilitation of cartilage-regenerative interventions, especially after autologous chondrocyte transplantation, is a scientifically well-studied field. There are several randomized, controlled studies with a follow-up of up to 10 years that surveyed various follow-up treatment schemes [2–5, 15].
The extent of postoperative weightbearing of the treated leg plays an important role in early rehabilitation after cartilage intervention. Especially in that point the rehabilitation differs significantly from other sport-orthopedic interventions such as anterior cruciate ligament reconstructions (ACLR) or meniscus surgery. Already in a review from 2006 it became apparent that the point in time at which full weight-bearing was permitted varied greatly between the different centers; for patellofemoral interventions between 6 hours and 12 weeks [9]. Because the patella does not articulate with the trochlea in full extension up to about 20° flexion, or only to an extent, in 2003 the "Oscell protocol" stipulated direct postoperative full weight bearing with a permitted range of motion (ROM) of 0/0/30 recommended [1]. This recommendation was also made in a consensus of US orthopedists in 2020 [8]. A scientific investigation in the sense of a controlled study or a specific clinical and/or radiological trials of this early full weight-bearing has not yet taken place. Wondrasch and Ebert examined the radiological and functional outcome of earlier full weightbearing (after up to 6 weeks) in multiple studies with a follow-up of up to 10 years and showed that a scheme with increasing weight-bearing with return to full weight-bearing after 6 weeks is safe. In all those randomized controlled trials, patients were prescribed a range of motion (ROM) controlled orthosis as well as CPM (Continuous Passive Motion). The flexion for the CPM was limited to 30°-40° and the use was recommended for 1-3 hours a day [1, 3, 8, 12, 15]. The use of passive motor movement can be found in many study protocols and aftercare recommendations from various societies and centers after cartilage regenerative interventions even though there are no randomized controlled studies on their use after cartilage regenerative therapies. Individual studies have demonstrated an advantage both subjectively and histologically [13].
One subject which is implemented in many rehabilitation protocols, but was never studied individually is the need and duration of postoperative immobilization or bed rest.
Throughout the whole rehabilitation process the integrity and safety of the “new” cartilage plays the most important role and influence not only early rehabilitation. That is also the reason why it is reasonable to refer cartilage patient to physiotherapeutic facilities that are familiar with the aftercare, so that the right amount of training is applied. In comparison to ACLR return to low- and high-impact sports are recommended at later timepoints for patients who underwent cartilage repair. Study protocols and recommendations from different cartilage societies show similar timeframes for return to different sport intensities: very-low-impact (ergometer, walking, exercises in closed-chain) after 7 weeks, rowing ergometer, cross-trainer, and open-chain exercises after 12 weeks, jogging (starting on a treadmill) after 6 months and return to high-impact-sports after 1 year [2, 6, 7, 10, 14]. Whereas the late rehabilitation is not as well studied scientifically as the early rehabilitation, such that there are no controlled trials on that topic. One study of Niethammer at al. from 2014 showed within a group of 44 patients, that the ones returning to high-impact sports after 12 months or more, showed significantly better results after two years [11].
In summary: we definitely need special concepts for patients undergoing cartilage repair. Many aspects of the rehabilitation are scientifically well studied, but many open questions remain, such as postoperative bed rest, very early full weight-bearing after cartilage repair in the patellofemoral compartment, and timepoints in return to low- and high-impact sports as well as patient-and therapeutic-individual cofounders.
1. Bailey A, Goodstone N, Roberts S et al (2003) Rehabilitation after oswestry autologous-chondrocyte implantation: The Oscell protocol. Journal of Sport Rehabilitation 12:104–118. https://doi.org/10.1123/jsr.12.2.104
2. Ebert JR, Edwards PK, Fallon M et al (2017) Two-Year Outcomes of a Randomized Trial Investigating a 6-Week Return to Full Weightbearing after Matrix-Induced Autologous Chondrocyte Implantation. American Journal of Sports Medicine 45:838–848. https://doi.org/10.1177/0363546516673837
3. Ebert JR, Fallon M, Ackland TR et al (2020) Minimum 10-Year Clinical and Radiological Outcomes of a Randomized Controlled Trial Evaluating 2 Different Approaches to Full Weightbearing After Matrix-Induced Autologous Chondrocyte Implantation. American Journal of Sports Medicine 48:133–142. https://doi.org/10.1177/0363546519886548
4. Ebert JR, Fallon M, Wood DJ, Janes GC (2021) An accelerated 6-week return to full weight bearing after matrix-induced autologous chondrocyte implantation results in good clinical outcomes to 5 years post-surgery. Knee Surgery, Sports Traumatology, Arthroscopy. https://doi.org/10.1007/s00167-020-06422-6
5. Ebert JR, Fallon M, Zheng MH et al (2012) A randomized trial comparing accelerated and traditional approaches to postoperative weightbearing rehabilitation after matrix-induced autologous chondrocyte implantation: Findings at 5 years. American Journal of Sports Medicine 40:1527–1537. https://doi.org/10.1177/0363546512445167
6. Edwards PK, Ackland T, Ebert JR (2014) Clinical rehabilitation guidelines for matrix-induced autologous chondrocyte implantation on the tibiofemoral joint. Journal of Orthopaedic and Sports Physical Therapy 44:102–119. https://doi.org/10.2519/jospt.2014.5055
7. Edwards PK, Ackland TR, Ebert JR (2013) Accelerated weightbearing rehabilitation after matrix-induced autologous chondrocyte implantation in the tibiofemoral joint: Early clinical and radiological outcomes. American Journal of Sports Medicine 41:2314–2324. https://doi.org/10.1177/0363546513495637
8. Flanigan DC, Sherman SL, Chilelli B et al (2020) Consensus on Rehabilitation Guidelines among Orthopedic Surgeons in the United States following Use of Third-Generation Articular Cartilage Repair (MACI) for Treatment of Knee Cartilage Lesions. Cartilage. https://doi.org/10.1177/1947603520968876
9. Hambly K, Bobic V, Wondrasch B et al (2006) Autologous chondrocyte implantation postoperative care and rehabilitation: Science and practice. American Journal of Sports Medicine 34:1020–1038. https://doi.org/10.1177/0363546505281918
10. Hirschmüller A, Baur H, Braun S et al (2011) Rehabilitation after autologous chondrocyte implantation for isolated cartilage defects of the knee. American Journal of Sports Medicine 39:2686–2696. https://doi.org/10.1177/0363546511404204
11. Niethammer TR, Müller PE, Safi E et al (2014) Early resumption of physical activities leads to inferior clinical outcomes after matrix-based autologous chondrocyte implantation in the knee. Knee Surgery, Sports Traumatology, Arthroscopy 22:1345–1352. https://doi.org/10.1007/s00167-013-2583-z
12. Pietschmann MF, Horng A, Glaser C et al (2014) Post-treatment rehabilitation after autologous chondrocyte implantation: State of the art and recommendations of the clinical tissue regeneration study group of the German Society for Accident Surgery and the German Society for Orthopedics and Orthopedic. Unfallchirurg 117:235–241. https://doi.org/10.1007/s00113-012-2293-x
13. Rogan S, Taeymans J, Hirschmüller A et al (2013) Wirkung von passiven Motorbewegungsschienen nach knorpelregenerativen Eingriffen - eine systematische Literaturübersicht. Zeitschrift fur Orthopadie und Unfallchirurgie 151:468–474. https://doi.org/10.1055/s-0033-1350707
14. Villa S della, Kon E, Filardo G et al (2010) Does intensive rehabilitation permit early return to sport without compromising the clinical outcome after arthroscopic autologous chondrocyte implantation in highly competitive athletes? American Journal of Sports Medicine 38:68–77. https://doi.org/10.1177/0363546509348490
15. Wondrasch B, Zak L, Welsch GH, Marlovits S (2009) Effect of Accelerated Weightbearing after Matrix-Associated Autologous Chondrocyte Implantation on the Femoral Condyle on Radiographic and Clinical Outcome after 2 Years: A Prospective, Randomized Controlled Pilot Study. American Journal of Sports Medicine 37:88S-96S. https://doi.org/10.1177/0363546509351272