Continuous Passive Motion, Early Weight Bearing, and Active Motion following Knee Articular Cartilage Repair: Evidence for Clinical Practice

Assessment of a continuous passive motion assistive device in dogs following stifle surgery

Canine rehabilitation optimizes recovery and the quality of life in dogs with musculoskeletal conditions or after surgery. Achieving proper range of motion (ROM) is vital post-stifle surgery, often accomplished through manual therapy and active exercises. We investigated the mechanical performance of a continuous passive motion (CPM) device for dogs and its potential use in canine rehabilitation therapy. In the ethical review process, our research was accepted to be evaluated in a sample of four dogs that had undergone left stifle surgery. Each dog underwent four sessions with the device at three different speeds. Results showed the device replicated extension angles close to goniometer measurements used in manual therapy. Flexion was also achieved, but not to the same extent. A force threshold stopped the device, avoiding discomfort in dogs with restricted ROM. Dog-specific factors like body position, opposition to movement, limb size, stage of recovery, haircoat, and discomfort, appeared to influence device operation. Mechanical improvements to allow for enhanced flexion are recommended in future CPM device designs, including a resistance threshold that could be adjusted for individual dogs and stages of healing. This study serves as a foundation for future advancements in canine rehabilitation systems. A canine CPM device may provide an affordable option to improve ROM. This could be beneficial for dog owners, who may not be comfortable with manual therapy, to assist with home rehabilitation exercises.

Culturing Osteochondral Explants Under Rotary Shaking or After Removing Bone Marrow Elements Increases Explant Cellular Viability

BACKGROUND

Reduced viability in the deepest zones of osteochondral allografts (OCAs) can weaken the subchondral interface, potentially increasing the risk of failure. This reduction may result from nutritional imbalances due to uneven media distribution or interference from bone marrow elements.

PURPOSE

To investigate whether culturing OCAs using a rotary shaker or removing the bone marrow elements would increase graft cellular viability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bovine osteochondral explants were stored for 28 days at 4°C under 3 different conditions (n = 6 explants per group): static (control group), rotary shaker at 150 rpm (shaker group), and static after removal of bone marrow elements using a Waterpik device (Waterpik group). Chondrocyte viability was assessed using live/dead staining across the entire tissue and in each zone (superficial, middle, deep). Subchondral bone viability was assessed using TUNEL (terminal deoxynucleotidal transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling) staining to detect apoptotic cells.

RESULTS

Both shaker (64.2%; P = .010) and Waterpik (65.6%; P = .005) conditions showed significantly higher chondrocyte viability compared with control (49.8%). When samples were analyzed by zone, the shaker and Waterpik groups displayed higher cellular viability at the middle zone (shaker = 60.6%, P < .001; Waterpik = 56.1%, P < .001) and deep zone (shaker = 63.1%, P = .018; Waterpik = 61.5%, P = .025) than the control group (25.6% at middle zone; 32.8% at deep zone). Additionally, shaker (56.7%; P = .018) and Waterpik (51.4%; P = .007) groups demonstrated a lower percentage of apoptotic cells in subchondral bone compared with control (88.0%). No significant differences were observed between the shaker and Waterpik groups in any of the analyses.

CONCLUSION

Both rotary shaking and removal of bone marrow elements during storage of osteochondral explants led to higher chondrocyte viability at the middle and deep zones of the graft compared with the static storage condition. Enhancing nutrition delivery to the graft could improve its quality, potentially improving outcomes of OCA transplantation.

CLINICAL RELEVANCE

The use of a rotary shaker or the removal of bone marrow elements may significantly improve the culture conditions, increasing graft viability and integrity after OCA storage.

Mechanical Evaluation of Commercially Available Fibrin Sealants for Cartilage Repair

OBJECTIVE

Fibrin sealants are routinely used for intra-articular surgical fixation of cartilage fragments and implants. However, the mechanical properties of fibrin sealants in the context of cartilage repair are unknown. The purpose of this study was to characterize the adhesive and frictional properties of fibrin sealants using an ex vivo model.

DESIGN

Native bovine cartilage-bone composites were assembled with a single application of Tisseel or Vistaseal. Composites were tested in tension and lap shear. In addition, the coefficient of friction (COF) was measured in a native cartilage annulus model alone and with minced cartilage. Finally, the effect of a double application of fibrin sealant was evaluated.

RESULTS

There were no significant differences in tensile modulus, ultimate tensile strength (UTS), shear modulus, or ultimate shear strength (USS) between the 2 fibrin sealants. Both fibrin sealants demonstrated a UTS and USS of <8 and <30 kPa, respectively. There were no differences in COF between the sealants when tested alone or with minced cartilage. A double application of fibrin sealant did not alter the mechanical properties compared with a single application of fibrin sealant.

CONCLUSIONS

Fibrin sealant adhesive properties are not affected by the sealant type studied or the number of applications in a bovine cartilage-bone model. Fibrin sealant tribological properties are not affected by sealant type or the addition of minced cartilage. The adhesive properties of Tisseel and Vistaseal were less than those desired for the in vivo fixation of cartilage repair implants. These findings motivate the development of an improved cartilage-specific adhesive for cartilage repair applications.

The Most Common Rehabilitation Protocol After Matrix-Assisted Autologous Chondrocyte Implantation Is Immediate Partial Weight-Bearing and Continuous Passive Motion

Purpose

To perform a systematic review of postoperative rehabilitation protocols for third-generation autologous chondrocyte implantation (ACI) of the knee joint.

Methods

A systematic review was performed by searching PubMed, Cochrane Library, and EMBASE to locate randomized controlled trials that described a rehabilitation protocol following third-generation ACI of the knee joint. The search terms used were: "autologous" AND "chondrocyte" AND "randomized". Data extracted from each study included various components of postoperative rehabilitation, such as initial weight-bearing (WB) status and time to full WB, the use of continuous passive motion (CPM), the time to return to sports, and physical therapy (PT) modalities used and the timing of their initiation.

Results

Twenty-five studies (22 Level I, 3 Level II) met inclusion criteria, including a total of 905 patients undergoing treatment with ACI. The average patient age ranged from 29.1 to 54.8 years, and the mean follow-up time ranged from 3 months to 10.0 years. The average lesion size ranged from 1.9 to 5.8 cm², and the most common lesion location was the medial femoral condyle (n = 494). Twenty studies allowed partial WB postoperatively with all studies permitting full WB within 12 weeks. Twenty studies used CPM in their rehabilitation protocols and initiated its use within 24 hours postoperatively. Among 10 studies that reported time to return to sport, 9 (90%) allowed return by 12 months. While most protocols used strength training as well as the inclusion of proprioceptive training, there was disagreement on the timing and inclusion of specific PT modalities used during the rehabilitation process.

Conclusions

Based on the included studies, most rehabilitation protocols for third-generation ACI initiate CPM within 24 hours postoperatively and allow partial WB immediately following surgery with progression to full WB within 12 weeks. There is variation of the PT modalities used as well as the timing of their initiation.

Level of Evidence

Level II, systematic review of Level I-II studies.

Osteochondral Allografts in Knee Surgery: Narrative Review of Evidence to Date

Knee articular cartilage defects can result in significant pain and loss of function in active patients. Osteochondral allograft (OCA) transplantation offers a single-stage solution to address large chondral and osteochondral defects by resurfacing focal cartilage defects with mature hyaline cartilage. To date, OCA transplantation of the knee has demonstrated excellent clinical outcomes and long-term survivorship. However, significant variability still exists among clinicians with regard to parameters for graft acceptance, surgical technique, and rehabilitation. Technologies to optimize graft viability during storage, improve osseous integration of the allograft, and shorten recovery timelines after surgery continue to evolve. The purpose of this review is to examine the latest evidence on treatment indications, graft storage and surgical technique, patient outcomes and survivorship, and rehabilitation after surgery.

Estimation of Tibiofemoral Joint Contact Forces Using Foot Loads during Continuous Passive Motions

Continuous passive motion (CPM) machines are commonly used after various knee surgeries, but information on tibiofemoral forces (TFFs) during CPM cycles is limited. This study aimed to explore the changing trend of TFFs during CPM cycles under various ranges of motion (ROM) and body weights (BW) by establishing a two-dimensional mathematical model. TFFs were estimated by using joint angles, foot load, and leg−foot weight. Eleven healthy male participants were tested with ROM ranging from 0° to 120°. The values of the peak TFFs during knee flexion were higher than those during knee extension, varying nonlinearly with ROM. BW had a significant main effect on the peak TFFs and tibiofemoral shear forces, while ROM had a limited effect on the peak TFFs. No significant interaction effects were observed between BW and ROM for each peak TFF, whereas a strong linear correlation existed between the peak tibiofemoral compressive forces (TFCFs) and the peak resultant TFFs (R2 = 0.971, p < 0.01). The proposed method showed promise in serving as an input for optimizing rehabilitation devices.

Rehabilitation Variability Following Osteochondral Autograft and Allograft Transplantation of the Knee

OBJECTIVE

The aim of this study is to assess the variability of postoperative rehabilitation protocols used by orthopedic surgery residency programs for osteochondral autograft transplantation (OAT) and osteochondral allograft transplantation (OCA) of the knee.

DESIGN

Online postoperative OAT and OCA rehabilitation protocols from US orthopedic programs and the scientific literature were reviewed. A custom scoring rubric was developed to analyze each protocol for the presence of discrete rehabilitation modalities and the timing of each intervention.

RESULTS

A total of 16 programs (10.3%) from 155 US academic orthopedic programs published online protocols and a total of 35 protocols were analyzed. Twenty-one protocols (88%) recommended immediate postoperative bracing following OAT and 17 protocols (100%) recommended immediate postoperative bracing following OCA. The average time protocols permitted weight-bearing as tolerated (WBAT) was 5.2 weeks (range = 0-8 weeks) following OAT and 6.2 weeks (range = 0-8 weeks) following OCA. There was considerable variation in the inclusion and timing of strength, proprioception, agility, and pivoting exercises. Following OAT, 2 protocols (8%) recommended functional testing as criteria for return to sport at an average time of 12.0 weeks (range = 12-24 weeks). Following OCA, 1 protocol (6%) recommended functional testing as criteria for return to sport at an average time of 12.0 weeks (range = 12-24 weeks).

CONCLUSION

A minority of US academic orthopedic programs publish OAT and OCA rehabilitation protocols online. Among the protocols currently available, there is significant variability in the inclusion of specific rehabilitation components and timing of many modalities. Evidence-based standardization of elements of postoperative rehabilitation may help improve patient care and subsequent outcomes.

Prolonged Application of Continuous Passive Movement Improves the Postoperative Recovery of Tibial Head Fractures: A Prospective Randomized Controlled Study

Methods

60 patients with THFs were randomly and equally divided into the CPM group and non-CPM group. Both groups immediately received CPM and conventional physical therapies during hospitalization. After discharge, the non-CPM group was treated with conventional physical therapy alone, while the CPM group received conventional physical training in combination with CPM treatment. At 6 weeks and 6 months postoperatively, the primary outcome which was knee ROM and the secondary outcome which was knee functionality and quality of life were evaluated.

Results

The CPM group had a significantly increased ROM at both follow-up time points. The Knee Society Score, UCLA activity score, and the EuroQoL as well as the pain analysis showed significantly better results of the CPM group than the non-CPM group.

Conclusions

The prolonged application of CPM therapy is an effective method to improve the postoperative rehabilitation of THFs.

Timing of postoperative weightbearing in the treatment of traumatic chondral injuries of the knee in athletes - A systematic review of current concepts in clinical practice

BACKGROUND

Surgery aims to stimulate healing and enable a safe return to sport in athletes with symptomatic cartilage lesions of the knee. Timing of postoperative weightbearing is crucial, balancing a stimulation of the healing and avoiding reinjury.To explore current concepts of timing to partial and full weightbearing and rate of return to sport in athletes after articular cartilage surgery of the knee.Systematic Review of studies with level of evidence I-III.

METHODS

Four databases (Pubmed, Web of Science, Scopus and Embase) were searched using a predetermined keyword strategy. Two independent reviewers screened results according to inclusion and exclusion criteria. Modified Coleman Methodology Score (mCMS) was used for the quality assessment.

RESULTS

5294 records were found. Data from ten studies was extracted after duplicate removal, title and abstract screening and full-text evaluation. Eight of the ten studies included a detailed rehabilitation protocol, including 336 out of a total athletic population of 401. 62% began partial weightbearing (PWB) 1-2 weeks postoperatively, while 38% began within 3-4 weeks. The studies that had a later PWB all returned to full weightbearing (FWB) within 6-8 weeks. One study with early PWB returned to early FWB, while the other two returned 10-12 weeks postoperatively. "Return to Sport" (RTS) was the most common reported outcome measure, with most studies reporting RTS at 80% or higher.

CONCLUSION

There is no clear evidence that the timing of weightbearing (WB) affects the outcome and return to sport in athletes after surgery for focal full-thickness cartilage lesions of the knee. On the other hand, there seems to be no adverse effects in adopting an early WB strategy, currently defined differently by different authors. Further studies directly comparing the timing of WB for specific surgical procedures in athletes and with relevant control groups is recommended. There is a need for a consensus in regard to more exactly defining "early" vs "late" weightbearing in relation to a universal and precisely defined state of healing.

Rehabilitation Variability Following Femoral Condyle and Patellofemoral Microfracture Surgery of the Knee

OBJECTIVE

To assess the variability of postoperative rehabilitation protocols used by orthopedic surgery residency programs for microfracture of femoral condyle and patellofemoral lesions of the knee.

DESIGN

Online postoperative microfracture rehabilitation protocols from US orthopedic programs and the scientific literature were reviewed. A custom scoring rubric was developed to analyze each protocol for the presence of discrete rehabilitation modalities and the timing of each intervention.

RESULTS

A total of 18 programs (11.6%) from 155 US academic orthopedic programs' published online protocols and a total of 44 protocols were analyzed. Seventeen protocols (56.7%) recommended immediate postoperative bracing for femoral condyle lesions and 17 (89.5%) recommended immediate postoperative bracing for patellofemoral lesions. The average time to permitting weight-bearing as tolerated (WBAT) was 6.1 weeks (range, 0-8) for femoral condyle lesions and 3.7 weeks (range, 0-8 weeks) for patellofemoral lesions. There was considerable variation in the inclusion and timing of strength, proprioception, agility, and pivoting exercises. For femoral condyle lesions, 10 protocols (33.3%) recommended functional testing prior to return to sport at an average of 23.3 weeks postoperatively (range, 12-32 weeks). For patellofemoral lesions, 4 protocols (20.0%) recommended functional testing for return to sport at an average of 21.0 weeks postoperatively (range, 12-32 weeks).

CONCLUSION

A minority of US academic orthopedic programs publish microfracture rehabilitation protocols online. Among the protocols currently available, there is significant variability in the inclusion of specific rehabilitation components and timing of many modalities. Evidence-based standardization of elements of postoperative rehabilitation may help improve patient care and subsequent outcomes.

Progress in the mechanical modulation of cell functions in tissue engineering

In mammals, mechanics at multiple stages-nucleus to cell to ECM-underlie multiple physiological and pathological functions from its development to reproduction to death. Under this inspiration, substantial research has established the role of multiple aspects of mechanics in regulating fundamental cellular processes, including spreading, migration, growth, proliferation, and differentiation. However, our understanding of how these mechanical mechanisms are orchestrated or tuned at different stages to maintain or restore the healthy environment at the tissue or organ level remains largely a mystery. Over the past few decades, research in the mechanical manipulation of the surrounding environment-known as substrate or matrix or scaffold on which, or within which, cells are seeded-has been exceptionally enriched in the field of tissue engineering and regenerative medicine. To do so, traditional tissue engineering aims at recapitulating key mechanical milestones of native ECM into a substrate for guiding the cell fate and functions towards specific tissue regeneration. Despite tremendous progress, a big puzzle that remains is how the cells compute a host of mechanical cues, such as stiffness (elasticity), viscoelasticity, plasticity, non-linear elasticity, anisotropy, mechanical forces, and mechanical memory, into many biological functions in a cooperative, controlled, and safe manner. High throughput understanding of key cellular decisions as well as associated mechanosensitive downstream signaling pathway(s) for executing these decisions in response to mechanical cues, solo or combined, is essential to address this issue. While many reports have been made towards the progress and understanding of mechanical cues-particularly, substrate bulk stiffness and viscoelasticity-in regulating the cellular responses, a complete picture of mechanical cues is lacking. This review highlights a comprehensive view on the mechanical cues that are linked to modulate many cellular functions and consequent tissue functionality. For a very basic understanding, a brief discussion of the key mechanical players of ECM and the principle of mechanotransduction process is outlined. In addition, this review gathers together the most important data on the stiffness of various cells and ECM components as well as various tissues/organs and proposes an associated link from the mechanical perspective that is not yet reported. Finally, beyond addressing the challenges involved in tuning the interplaying mechanical cues in an independent manner, emerging advances in designing biomaterials for tissue engineering are also explored.

Ectopic models recapitulating morphological and functional features of articular cartilage

BACKGROUND

Articular cartilage is an extremely specialized connective tissue which covers all diarthrodial joints. Implantation of chondrogenic cells without or with additional biomaterial scaffolds in ectopic locationsin vivo generates substitutes of cartilage with structural and functional characteristics that are used in fundamental investigations while also serving as a basis for translational studies.

METHODS

Literature search in Pubmed.

RESULTS AND DISCUSSION

This narrative review summarizes the most relevant ectopic models, among which subcutaneous, intramuscular, and kidney capsule transplantation and elaborates on implanted cells and biomaterial scaffolds and on their use to recapitulate morphological and functional features of articular cartilage. Although the absence of a physiological joint environment and biomechanical stimuli is the major limiting factor, ectopic models are an established component for articular cartilage research aiming to generate a bridge between in vitro data and the clinically more relevant translational orthotopic in vivo models when their limitations are considered.

Mechano-activated biomolecule release in regenerating load-bearing tissue microenvironments

Although mechanical loads are integral for musculoskeletal tissue homeostasis, overloading and traumatic events can result in tissue injury. Conventional drug delivery approaches for musculoskeletal tissue repair employ localized drug injections. However, rapid drug clearance and inadequate synchronization of molecule provision with healing progression render these methods ineffective. To overcome this, a programmable mechanoresponsive drug delivery system was developed that utilizes the mechanical environment of the tissue during rehabilitation (for example, during cartilage repair) to trigger biomolecule provision. For this, a suite of mechanically-activated microcapsules (MAMCs) with different rupture profiles was generated in a single fabrication batch via osmotic annealing of double emulsions. MAMC physical dimensions were found to dictate mechano-activation in 2D and 3D environments and their stability in vitro and in vivo, demonstrating the tunability of this system. In models of cartilage regeneration, MAMCs did not interfere with tissue growth and activated depending on the mechanical properties of the regenerating tissue. Finally, biologically active anti-inflammatory agents were encapsulated and released from MAMCs, which counteracted degradative cues and prevented the loss of matrix in living tissue environments. This unique technology has tremendous potential for implementation across a wide array of musculoskeletal conditions for enhanced repair of load-bearing tissues.

Rehabilitation exercise program after surgical treatment of quadriceps tendon rupture: A case report

OBJECTIVES

This case report describes in detail the rehabilitation exercise program, provide post-operative therapeutic objectives/recommendations and to facilitate the return to a possible schedule of ADL and participation in sports after the surgical treatment of quadriceps tendon rupture. Also, the exact surgical technique is described.

DESIGN

A single case report.

PARTICIPANT

The patient was an active 53-year-old man who sustained this injury as a result of a sudden misstep with his left foot into a hole, while he was trekking across muddy countryside. Clinical examination of the knee revealed skin ecchymosis, swelling and tenderness over the distal thigh. Plain radiographs showed patella baja, and the scheduled magnetic resonance imaging (MRI) showed interrupted continuity of the quadriceps tendon and the patella. A diagnosis of quadriceps tendon rupture was made and the patient was scheduled to undergo surgical intervention the following day.

REHABILITATION EXERCISE PROGRAM

A well-structured rehabilitation exercise program was followed in order to ensure rapid recovery and good functional outcomes. His postoperative course progressed normally, demonstrating a return to the normal activities of daily living at 6 weeks, full active range of motion at 16 weeks, and return to sports recreational activities at 5 months.

CONCLUSIONS

An early surgical treatment and subsequently a well-structured rehabilitation exercise program have contributed to maximize the functional outcomes of the patient and provide a rapid and safe return to the activities of daily living (7th week) with participation in non-contact sports after the 18th week.

Dynamic Compressive Loading Improves Cartilage Repair in an In Vitro Model of Microfracture: Comparison of 2 Mechanical Loading Regimens on Simulated Microfracture Based on Fibrin Gel Scaffolds Encapsulating Connective Tissue Progenitor Cells

BACKGROUND

Microfracture of focal chondral defects often produces fibrocartilage, which inconsistently integrates with the surrounding native tissue and possesses inferior mechanical properties compared with hyaline cartilage. Mechanical loading modulates cartilage during development, but it remains unclear how loads produced in the course of postoperative rehabilitation affect the formation of the new fibrocartilaginous tissue.

PURPOSE

To assess the influence of different mechanical loading regimens, including dynamic compressive stress or rotational shear stress, on an in vitro model of microfracture repair based on fibrin gel scaffolds encapsulating connective tissue progenitor cells.

STUDY DESIGN

Controlled laboratory study.

METHODS

Cylindrical cores were made in bovine hyaline cartilage explants and filled with either (1) cartilage plug returned to original location (positive control), (2) fibrin gel (negative control), or (3) fibrin gel with encapsulated connective tissue progenitor cells (microfracture mimic). Constructs were then subjected to 1 of 3 loading regimens: (1) no loading (ie, unloaded), (2) dynamic compressive loading, or (3) rotational shear loading. On days 0, 7, 14, and 21, the integration strength between the outer chondral ring and the central insert was measured with an electroforce mechanical tester. The central core component, mimicking microfracture neotissue, was also analyzed for gene expression by real-time reverse-transcription polymerase chain reaction, glycosaminoglycan, and double-stranded DNA contents, and tissue morphology was analyzed histologically.

RESULTS

Integration strengths between the outer chondral ring and central neotissue of the cartilage plug and fibrin + cells groups significantly increased upon exposure to compressive loading compared with day 0 controls (P = .007). Compressive loading upregulated expression of chondrogenesis-associated genes (SRY-related HGMG box-containing gene 9 [SOX9], collagen type II α1 [COL2A1], and increased ratio of COL2A1 to collagen type I α1 [COL1A1], an indicator of more hyaline phenotype) in the neotissue of the fibrin + cells group compared with the unloaded group at day 21 (SOX9, P = .0032; COL2A1, P < .0001; COL2A1:COL1A1, P = .0308). Fibrin + cells constructs exposed to shear loading expressed higher levels of chondrogenic genes compared with the unloaded condition, but the levels were not as high as those for the compressive loading condition. Furthermore, catabolic markers (MMP3 and ADAMTS 5) were significantly upregulated by shear loading (P = .0234 and P < .0001, respectively) at day 21 compared with day 0.

CONCLUSION

Dynamic compressive loading enhanced neotissue chondrogenesis and maturation in a simulated in vitro model of microfracture, with generation of more hyaline-like cartilage and improved integration with the surrounding tissue.

CLINICAL RELEVANCE

Controlled loading after microfracture may be beneficial in promoting the formation of more hyaline-like cartilage repair tissue; however, the loading regimens applied in this in vitro model do not yet fully reproduce the complex loading patterns created during clinical rehabilitation. Further optimization of in vitro models of cartilage repair may ultimately inform rehabilitation protocols.

Assessing Foot Loads in Continuous Passive Motion (CPM) and Active Knee Joint Motion Devices

BACKGROUND

Continuous passive motion (CPM) and active knee joint motion devices are commonly applied after various surgical procedures. Despite the growing use of active motion devices, there is a paucity of data comparing plantar loads between the different mobilization techniques. The aim of this study was to investigate foot loads during knee joint mobilization in continuous passive and active knee joint motion devices and to compare this data to the physiological load of full weight-bearing.

PATIENTS/MATERIAL AND METHODS

Fifteen healthy participants (7 women and 8 men, 25 ± 3 years, 66 ± 6 kg, 175 ± 10 cm, BMI 21.9 ± 2) were recruited. Plantar loads were measured via dynamic pedobarography using a continuous passive motion device (ARTROMOT-K1, ORMED GmbH, Freiburg, Germany) and an active motion device (CAMOped, OPED AG, Cham, Switzerland), each with a restricted range of motion of 0-0-90° (ex/flex) and free ROM for the knee joint. For the active motion device, cycles were performed at four different resistance levels (0-III). Data were assessed using the pedar^® X system (Novel Inc., Munich, Germany), which monitors loads from the foot-sole interface. Force values were compared between motion devices and normal gait, which served as the reference for conditions of full weight-bearing. P-values of < 0.05 were considered statistically significant.

RESULTS

Normal gait revealed peak forces of 694 ± 96 N, defined as 100 %. The CPM device produced plantar forces of less than 1.5 N. Using the active motion device in the setting of 0-0-90° produced foot loads of < 1.5 N (resistance 0-II) and 3.4 ± 9.3 N with a resistance of III (p < 0.001). Conditions of free ROM resulted in foot loads of 4.5 ± 4.5 N (resistance 0), 7.7 ± 10.7 N (resistance I), 6.7 ± 10.4 (resistance II) and 6.7 ± 6.9 N with a resistance of III (p < 0.001), corresponding to 0.6 %, 1.1 %, 1.0 % and 1.0 % of full weight-bearing, respectively.

CONCLUSION

Motion exercises of the knee joint can be performed both with passive and active devices in accordance with strict weight-bearing restrictions, which are often recommended by surgeons. Also, active motion devices can be used when the ankle joint or foot have to be offloaded. Further studies assessing intraarticular joint load conditions have to be performed to confirm the findings obtained in this study.

Microfracture of Articular Cartilage

Microfracture is a treatment option for symptomatic, full-thickness cartilage defects. Microfracture is most likely to be successful when performed in nonobese patients under the age of thirty years for small (<2 to 4-cm2) femoral condylar defects that have been symptomatic for a short time (less than twelve to twenty-four months). Microfracture has acceptable short-term clinical results, but results can be expected to decline over time. Long-term studies that compare microfracture with advanced cartilage restoration techniques are required to ascertain whether these newer techniques provide longer-lasting results.

Is Delayed Weightbearing After Matrix-Associated Autologous Chondrocyte Implantation in the Knee Associated With Better Outcomes? A Systematic Review of Randomized Controlled Trials

Background:

Proper rehabilitation after matrix-associated autologous chondrocyte implantation (MACI) is essential to restore a patient’s normal function without overloading the repair site.

Purpose:

To evaluate the current literature to assess clinical outcomes of MACI in the knee based on postoperative rehabilitation protocols, namely, the time to return to full weightbearing (WB).

Study Design:

Systematic review; Level of evidence, 1.

Methods:

A systematic review was performed to locate studies of level 1 evidence comparing the outcomes of patients who underwent MACI with a 6-week, 8-week, or 10/11-week time period to return to full WB. Patient-reported outcomes assessed included the Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, Short Form Health Survey–36 (SF-36), and visual analog scale (VAS) for pain frequency and severity.

Results:

Seven studies met the inclusion criteria, including a total of 136 patients (138 lesions) who underwent MACI. Treatment failure had occurred in 0.0% of patients in the 6-week group, 7.5% in the 8-week group, and 8.3% in the 10/11-week group at a mean follow-up of 2.5 years (P = .46). KOOS, SF-36, and VAS scores in each group improved significantly from preoperatively to follow-up (P < .001).

Conclusion:

Patients undergoing MACI in the knee can be expected to experience improvement in clinical outcomes with the rehabilitation protocols outlined in this work. No significant differences were seen in failure rates based on the time to return to full WB.

No evidence for the most appropriate postoperative rehabilitation protocol following anterior cruciate ligament reconstruction with concomitant articular cartilage lesions: a systematic review

PURPOSE

Anterior cruciate ligament (ACL) rupture commonly occurs in conjunction with articular cartilage injury. However, there is no consensus on the most appropriate rehabilitation which should be carried out for ACL reconstruction (ACLR) and the surgical management of articular cartilage lesions of the knee. The purpose of this study was to systematically review the literature to investigate the recommended rehabilitation protocol for patients undergoing ACLR with concomitant articular cartilage injury with a view to develop guidelines on the most appropriate treatment.

METHODS

Two reviewers independently searched five database for randomised controlled trials (RCTs), non-randomised comparative and retrospective cohort studies (CS) describing the management of concomitant ACL rupture and articular cartilage injury and the postoperative rehabilitation regimen. Risk of bias was performed using a modified Downs & Black's checklist. The primary outcome was specific rehabilitation protocols including weight-bearing status, immobilisation, continuous passive motion (CPM), and return to play criteria. Secondary outcomes included patient-reported outcomes. A best evidence synthesis was performed.

RESULTS

The review yielded six studies which reported on rehabilitation techniques. All studies were of low methodological quality. There was considerable variability in not only the chondral lesion reported but also the treatment techniques utilised and especially the rehabilitation regimes. No consensus was found on weight-bearing status, postoperative immobilisation, the use of CPM, or return to play criteria. Given the quality of the papers, there was no evidence to recommend any specific rehabilitation regime in the postoperative management of concomitant ACLR and articular cartilage lesions.

CONCLUSION

This systematic review revealed that despite how common concomitant ACL rupture and articular cartilage injury is, there is no evidence to support one, most appropriate rehabilitation protocol. From a clinical perspective, decisions on postoperative rehabilitation for patients undergoing ACLR and treatment of articular cartilage lesions should be made on a case-by-case basis with criteria-based progression until more robust evidence becomes available. A list of specific rehabilitation protocols based on the cartilage restoration technique is provided.

LEVEL OF EVIDENCE

IV.

Rehabilitation and Postoperative Management Practices After Osteochondral Allograft Transplants to the Distal Femur: A Report From the Metrics of Osteochondral Allografts (MOCA) Study Group 2016 Survey

Context:

We present the current spectrum of postoperative management practices for patients receiving distal femur osteochondral allograft (OCA) transplants.

Evidence Acquisition:

The Joint Restoration Foundation database was examined in cooperation with the Metrics of Osteochondral Allografts study group to identify 121 surgeons who had performed at least 1 OCA transplant in the past year; 63% of surgeons responded.

Study Design:

Clinical survey.

Level of Evidence:

Level 3.

Results:

Postoperative weightbearing restrictions ranged from immediate nonweightbearing with full weightbearing by 12 weeks to immediate weightbearing as tolerated. Most surgeons who performed fewer (<10) OCA transplants per year followed the most restrictive protocol, while surgeons who performed more (>20) OCA transplants per year followed the least restrictive protocol. One-third of surgeons with the most restrictive protocol were more likely to change their protocol to be less restrictive over time, while none of those with the least restrictive protocol changed their protocol over time. Fifty-five percent of surgeons permitted return to full activity at 26 weeks, while 27% of surgeons lifted restrictions at 16 weeks.

Conclusion:

Characterization of the spectrum of postoperative management practices after OCA transplantation provides a foundation for future investigations regarding patient outcomes and associated cost to establish best practice guidelines. Fundamentally, surgeons with more experience with this procedure tended to be more aggressive with their postoperative rehabilitation guidelines. Most commonly, rehabilitation provided for some degree of limited weightbearing; however, the spectrum also included immediate full weightbearing practices.

High fat diet accelerates cartilage repair in DBA/1 mice

Obesity is a well-known risk factor for osteoarthritis, but it is unknown what it does on cartilage repair. Here we investigated whether a high fat diet (HFD) influences cartilage repair in a mouse model of cartilage repair. We fed DBA/1 mice control or HFD (60% energy from fat). After 2 weeks, a full thickness cartilage defect was made in the trochlear groove. Mice were sacrificed, 1, 8, and 24 weeks after operation. Cartilage repair was evaluated on histology. Serum glucose, insulin and amyloid A were measured 24 h before operation and at endpoints. Immunohistochemical staining was performed on synovium and adipose tissue to evaluate macrophage infiltration and phenotype. One week after operation, mice on HFD had defect filling with fibroblast-like cells and more cartilage repair as indicated by a lower Pineda score. After 8 weeks, mice on a HFD still had a lower Pineda score. After 24 weeks, no mice had complete cartilage repair and we did not detect a significant difference in cartilage repair between diets. Bodyweight was increased by HFD, whereas serum glucose, amyloid A and insulin were not influenced. Macrophage infiltration and phenotype in adipose tissue and synovium were not influenced by HFD. In contrast to common wisdom, HFD accelerated intrinsic cartilage repair in DBA/1 mice on the short term. Resistance to HFD induced inflammatory and metabolic changes could be associated with accelerated cartilage repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1258-1264, 2017.

Comparison of Collagen Graft Fixation Methods in the Porcine Knee: Implications for Matrix-Assisted Chondrocyte Implantation and Second-Generation Autologous Chondrocyte Implantation

PURPOSE

To evaluate the fixation integrity at time zero of a type I/III collagen patch secured to a chondral defect in the porcine knee using methods typically employed in autologous chondrocyte implantation (ACI) and matrix-assisted chondrocyte implantation.

METHODS

Twenty-four porcine knee specimens underwent a medial parapatellar arthrotomy. A prefabricated template was used to create cartilage defects of 2 cm(2) in the medial femoral condyle. A size-matched collagen patch was fashioned. Four methods of fixation to the chondral defect were analyzed: group 1-saline, group 2-fibrin glue around the periphery of the patch, group 3-fibrin glue applied to the base of the defect and around the periphery of the patch, group 4-6-0 vicryl suture and fibrin glue around the periphery of the patch. Collagen patch fixation was assessed at intervals of 60, 300, 600, 900, and 1,200 cycles from full extension to 90° of flexion, performed manually without application of axial force. Patch fixation was evaluated by 2 independent observers using a customized scoring scale.

RESULTS

Mean peripheral detachment of the patch and chondral defect uncovering remained less than 25% for all groups. Area of defect uncovering was significantly increased in group 2 compared with group 4 after 900 and 1,200 cycles (P = .0014 and P = .0025, respectively). Fibrin glue applied to the base of the defect, or suturing of the patch, reduced deformation significantly after 900 cycles.

CONCLUSIONS

Suture increases the stability of fixation of a type I/III collagen patch to a chondral defect better than fibrin glue alone in the porcine knee after repetitive cycling, with respect to patch detachment and chondral defect uncovering. Application of fibrin glue to the base of the defect, or securing the patch with suture, decreases collagen patch deformation.

CLINICAL RELEVANCE

In cases where minimally invasive techniques do not allow suture fixation of the collagen patch, scaffold fixation may be compromised during articular motion protocols typically used after second- and third-generation ACI procedures.

The role of rehabilitation following autologous chondrocyte implantation: a retrospective chart review

PURPOSE/BACKGROUND

Clinical outcomes following autologous chondrocyte implantation (ACI) are influenced by multiple factors, including patient demographics, lesion characteristics, quality of the surgical repair, and post-operative rehabilitation. However, it is currently unknown what specific characteristics of rehabilitation have the greatest influence on clinical outcomes following ACI. The purpose of this study was to conduct a retrospective chart review of patients undergoing ACI with the intent to describe this patient population's demographics, clinical outcomes, and rehabilitation practices. This study aimed to assess the consistency of the documentation process relative to post-operative rehabilitation in order to provide information and guide initiatives for improving the quality of rehabilitation practices following ACI.

METHODS

The medical records of patients treated for chondral defect(s) of the knee who subsequently underwent the ACI procedure were retrospectively reviewed. A systematic review of medical, surgical, and rehabilitation records was performed. In addition, patient-reported outcome measures (IKDC, WOMAC, Lysholm, SF-36) recorded pre-operatively, and 3, 6, and 12 months post-operatively were extracted from an existing database.

RESULTS

20 medical charts (35.9 ± 6.8 years; 9 male, 11 female) were systematically reviewed. The average IKDC, WOMAC, Lysholm, and SF-36 scores all improved from baseline to 3, 6 and 12 months post-operatively, with the greatest changes occurring at 6 and 12 months. There was inconsistent documentation relative to post-operative rehabilitation, including CPM use, weight-bearing progression, home-exercise compliance, and strength progressions.

CONCLUSIONS

Due to variations in the documentation process, the authors were unable to determine what specific components of rehabilitation influence the recovery process. In order to further understand how rehabilitation practices influence outcomes following ACI, specific components of the rehabilitation process must be consistently and systematically documented over time.

LEVEL OF EVIDENCE

2C.

The effect of osteochondral regeneration using polymer constructs and continuous passive motion therapy in the lower weight-bearing zone of femoral trocheal groove in rabbits

Remedying patellofemoral osteochondral defects using clinical therapy remains challenging. Construct-based and cell-based regenerative medicine with in vitro physical stimuli has been progressively implemented. However, the effect of physical stimuli in situ in knee joints with degradable constructs is still not well-documented. Therefore, we studied whether it was practical to achieve articular cartilage repair using a poly(lactic-co-glycolic acid) (PLGA) construct in addition to early short-term continuous passive motion (CPM) for treatment of full-thickness osteochondral defects in the lower-weigh bearing (LWB) zone of the femoral trocheal groove. Twenty-six rabbits were randomly allocated into either intermittent active motion (IAM) or CPM treatment groups with or without PLGA constructs, termed PLGA construct-implanted (PCI) and empty defect knee models, respectively. Gross observation, histology, inflammatory cells, which were identified using H&E staining, total collagen and alignment, studied qualitatively using Masson's trichrome staining, glycosaminoglycan (GAG), identified using Alcian blue staining, and newly formed bone, observed using micro-CT, were evaluated at 4 and 12 weeks after surgery. Repair of osteochondral defects in the PCI-CPM group was more promising than all other groups. The better osteochondral defect repair in the PCI-CPM group corresponded to smooth cartilage surfaces, no inflammatory reaction, hyaline cartilaginous tissues composition, sound collagen alignment with positive collagen type II expression, higher GAG content, mature bone regeneration with osteocyte, clear tidemark formation, and better degradation of PLGA. In summary, the use of a simple PLGA construct coupled with passive motion promotes positive healing and may be a promising clinical intervention for osteochondral regeneration in LWB defects.

Sensitivity of magnetic resonance imaging for detection of patellofemoral articular cartilage defects

PURPOSE

Chondral defects within the patellofemoral compartment are common and lack the ability to heal on their own. Early detection of these lesions with a noninvasive modality would be beneficial in delaying or preventing their possible progression to osteoarthritis. We hypothesized that magnetic resonance imaging (MRI) is a sensitive, specific, and accurate imaging modality for the detection of patellofemoral chondral defects with substantial interobserver reliability and that MRI has a higher sensitivity, specificity, and accuracy for detecting patellar defects than trochlear defects.

METHODS

A systematic review of multiple medical databases was performed by use of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol. Analysis of studies that reported diagnostic performance of MRI in the assessment of patellofemoral chondral defects (patella and trochlea), using arthroscopy as the reference gold standard, was performed. Sensitivity, specificity, accuracy, and interobserver reliability were reported. Significant heterogeneity across studies precluded meta-analysis.

RESULTS

MRI was more sensitive in detection of patellar (87%) versus trochlear (72%) defects. MRI was similarly specific for patellar (86%) and trochlear (89%) defects. MRI was similarly accurate for patellar (84%) and trochlear (83%) defects. Interobserver agreement was substantial to almost perfect for both patellar and trochlear defects.

CONCLUSIONS

MRI is a highly sensitive, specific, and accurate noninvasive diagnostic modality for the detection of chondral defects in the patellofemoral compartment of the knee, using arthroscopy as the reference gold standard. Although there was wide variability in the statistical parameters assessed, MRI was more sensitive for detection of patellar versus trochlear defects and similarly specific and accurate for patellar and trochlear defects. Interobserver reliability is substantial to near perfect in the assessment of these lesions, without a significant difference between patellar and trochlear defects.

CLINICAL RELEVANCE

Use of MRI may allow early detection of chondral defects within the patellofemoral compartment, enabling clinicians to adopt strategies to delay or prevent progression to osteoarthritis.

LEVEL OF EVIDENCE

Level III, systematic review of Level I, II, and III studies.

Biomechanical outcomes of cartilage repair of the knee

Cartilage repair and restoration has become an increasingly popular surgical technique to provide symptomatic relief to young patients with focal articular cartilage defects. Given the high level of interest and improvement in surgical techniques to perform cartilage repair or restoration, it is important that patient-reported, surgical and functional outcomes are evaluated both in the short term and long term. Despite the high levels of interest in cartilage repair and restoration techniques, there are few studies that have evaluated the effects of cartilage surgery on biomechanical and neuromuscular function of the joint and the lower extremity. The focus of the following review is to evaluate the current evidence available on biomechanical functional outcomes after cartilage repair with clinical applications to the rehabilitation process.

The combined effects of continuous passive motion treatment and acellular PLGA implants on osteochondral regeneration in the rabbit

We investigated the active role of clinical rehabilitation in osteochondral regeneration using continuous passive motion (CPM) treatment together with acellular PLGA implants. CPM treatment was performed and compared with immobilization (Imm) treatment and intermittent active motion (IAM) treatment upon full-thickness osteochondral defects either with or without an PLGA implant in the PI (PLGA-implanted) and ED (empty defect) models. The PI and ED tests were performed in 38 rabbits for 4 and 12 weeks. At the end of testing, the PI-CPM group had the best regeneration with nearly normal articular surfaces and no joint contracture or inflammatory reaction. In contrast, degenerated joints, abrasion cartilage surfaces and synovitis were observed in the Imm and IAM groups. The achieved bone volume/tissue volume (BV/TV) ratio, which was measured using micro-CT, was significantly higher in the CPM group compared with the Imm and IAM groups; in particular, the performance of the PI-CPM group exceeds that of the ED-CPM group. The thickness of the trabecular (subchondral) bone was visibly increased in all of the groups from 4 through 12 weeks of testing. However, a histological analysis revealed differences in cartilage regeneration. At week 4, compared with the ED samples, all of the PI groups exhibited better collagen alignment and higher GAG content in the core of their repaired tissues, particularly in the PI-CPM group. At week 12, sound osteochondral repair and hyaline cartilaginous regeneration was observed in the PI-CPM group, and this was marked by type II collagen expression, osteocyte maturation, and trabecular boney deposition. In contrast, the PI-Imm and PI-IAM groups exhibited fibrocartilaginous tissues that had modest GAG content. In summary, this study demonstrates that early CPM treatment together with acellular PLGA implantation has significant positive effects on osteochondral regeneration in rabbit knee joint models.

Current concepts for rehabilitation and return to sport after knee articular cartilage repair in the athlete

Articular cartilage injury is observed with increasing frequency in both elite and amateur athletes and results from the significant acute and chronic joint stress associated with impact sports. Left untreated, articular cartilage defects can lead to chronic joint degeneration and athletic and functional disability. Treatment of articular cartilage defects in the athletic population presents a therapeutic challenge due to the high mechanical demands of athletic activity. Several articular cartilage repair techniques have been shown to successfully restore articular cartilage surfaces and allow athletes to return to high-impact sports. Postoperative rehabilitation is a critical component of the treatment process for athletic articular cartilage injury and should take into consideration the biology of the cartilage repair technique, cartilage defect characteristics, and each athlete's sport-specific demands to optimize functional outcome. Systematic, stepwise rehabilitation with criteria-based progression is recommended for an individualized rehabilitation of each athlete not only to achieve initial return to sport at the preinjury level but also to continue sports participation and reduce risk for reinjury or joint degeneration under the high mechanical demands of athletic activity.

Rehabilitation after Articular Cartilage Repair of the Knee in the Football (Soccer) Player

BACKGROUND

Participation in football can put both male and female players at an increased risk for knee osteoarthritis. There is a higher prevalence of focal chondral defects in the knee of athletes compared to nonathletes. The management of chondral defects in the football player is complex and multifactorial.

OBJECTIVE

The aim of this study is to provide an overview of the current strategies for rehabilitation after articular cartilage repair of the knee in the football player.

DESIGN

A review of current literature and the scientific evidence for rehabilitation after articular cartilage repair of the knee.

CONCLUSIONS

Articular cartilage repair has been shown to allow return to sport but rehabilitation timescales are lengthy. Successful rehabilitation for a return to football after articular cartilage repair of the knee requires the player to be able to accept the load of the sport. This necessitates a multidisciplinary approach to rehabilitation, especially in the transition from therapy to performance care. It should be recognized that not all players will return to football after articular cartilage repair. The evidence base for rehabilitative practice after articular cartilage repair is increasing but remains sparse in areas.