Tony G. van Tienen

Cross-linked type I and type II collagenous matrices for the repair of full-thickness articular cartilage defects—A study in rabbits

The physico-chemical properties of collagenous matrices may determine the tissue response after insertion into full-thickness articular cartilage defects. In this study, cross-linked type I and type II collagen matrices, with and without attached chondroitin sulfate, were implanted into full-thickness defects in the femoral trochlea of adolescent rabbits. The tissue response was evaluated 4 and 12 weeks after implantation by general histology and two semi-quantitative histological grading systems. Four weeks after implantation, type I collagenous matrices were completely filled with cartilage-like tissue. By contrast, type II collagenous matrices revealed predominantly cartilaginous tissue only at the superficial zone and at the interface of the matrix with the subchondral bone, leaving large areas of the matrix devoid of tissue. Attachment of chondroitin sulfate appeared to promote cellular ingrowth and cartilaginous tissue formation in both types of collagen matrices. Twelve weeks after implantation, the differences between the matrices were less pronounced. The deep parts of the subchondral defects were largely replaced by new bone with a concomitant degradation of the matrices. The original cartilage contours in defects with type I collagen-based matrices were repaired with fibro-cartilaginous tissue. Defects containing type II matrices showed an increase in the amount of superficial cartilage-like tissue. The original contour, however, was not completely restored in all animals, occasionally leaving a central depression or fissure. It is concluded that different types of collagen matrices induce different tissue responses in full-thickness articular cartilage defects. Type I collagen-based matrices are superior to guide progenitor cells from a subchondral origin into the defect. In type II collagen-based matrices cell migration is less, but invading cells are directed into a chondrocyte phenotype. Based on these observations it is suggested that a composite matrix consisting of a deep layer of type I collagen and a more superficial layer of type II collagen may be the matrix of choice for cartilage regeneration.

Effect on tissue differentiation and articular cartilage degradation of a polymer meniscus implant - A 2-year follow-up study in dogs

Background Replacement of the meniscus by an implant could potentially avoid cartilage degeneration. Hypothesis An implant of degradable polycaprolacton-polyurethane should act as a temporary scaffold enabling regeneration of a new meniscus by slow degradation of the polymer and simultaneous in-growth and differentiation of tissues into the typical cartilage-like tissue of the meniscus. Study Design Controlled laboratory study. Methods In 13 dogs’ knees, the lateral meniscus was replaced with a porous polymer implant (6 and 7 for 6- and 24-month follow-up, respectively); in 7 knees only a meniscectomy was performed. In 6 knees, no surgery was performed. After 6 and 24 months, the implants and the articular cartilage were histologically evaluated. Compression-stress tests were performed on implant biopsy specimens. Results The implants were fully integrated into the tissue without formation of a capsule. The foreign body reaction did not exceed grade I. Differentiation from fibrous- to cartilage-like tissue was pronounced after 24 months. Viable cells were particularly absent after 24 months in central parts of the most anterior part of the scaffold. The mechanical properties of the implants were intermediate between the scaffold before implantation and native meniscus tissue and were not different between 6 and 24 months. After both 6 and 24 months, small areas of the implant were not covered with tissue. Cartilage degeneration was not prevented. Conclusion A final remodeling of tissue into neomeniscus tissue could not take place since the original structure of the polymer was still present after 24 months. The implant did not prevent cartilage degradation. Several factors are discussed that may be responsible for this. Clinical Relevance Although clinical application of a polymer implant for the replacement of the entire meniscus is not supported by this study, the authors strongly believe in the concept, but further improvements in the implant and surgical technique are needed before such an implant can be recommended for human clinical use.

A porous polymer scaffold for meniscal lesion repair--a study in dogs.

Meniscal lesions often occur in the avascular area of the meniscus with little chance of spontaneous repair. An access channel in the meniscal tissue can function as an entrance for ingrowing repair tissue from the vascular periphery of the meniscus to the lesion in the avascular zone which again induced healing of the lesion. Implantation of a porous polymer in a full-thickness access channel induced healing. However, a better integration between meniscal tissue and the implant might be achieved with the combination of the newly developed porous polymers and a modified surgical technique. This might improve meniscal lesion healing and the repair of the access channel with neo-meniscal tissue. Longitudinal lesions were created in the avascular part of 24 canine lateral menisci and a partial-thickness access channel was formed to connect the lesion with the meniscal periphery. In 12 menisci, the access channel was left empty (control group), while in the remaining 12 menisci the polymer implant was sutured into the access channel. Repair of the longitudinal lesions was achieved with and without polymer implantation in the partial-thickness access channel. Polymer implants induced fibrous ingrowth with cartilaginous areas, which resembled neo-meniscal tissue. Implantation did not prevent articular cartilage degeneration.

Favorable results of acetabular reconstruction with impacted morsellized bone grafts in patients younger than 50 years: A 10- to 18-year follow-up study of 34 cemented total hip arthroplasties

We report a long-term review of 41 acetabular reconstructions using impacted morsellized bone grafts and a cemented total hip arthroplasty (THA) in patients younger than 50 (22-49; average 38) years. Reconstruction was performed in 23 primary THA (19 patients) and 18 revision THA (17 patients). 3 patients were lost to follow-up and 3 (4 hips) died within 10 years of surgery; none had a revision. Thus, 34 hips (30 patients) were reviewed with an average follow-up of 13 (10-18) years. In 2 hips, a revision was performed for aseptic loosening of the acetabular component 7 and 11 years after surgery. One additional cup was revised after 12 years during a femoral stem revision due to wear and matching problems, but was well fixed. The survival rate of the acetabular reconstruction technique was 94% (95% CI: 90-98%).

Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus.

Aim The Royal Dutch Society for Physical Therapy (KNGF) instructed a multidisciplinary group of Dutch anterior cruciate ligament (ACL) experts to develop an evidence statement for rehabilitation after ACL reconstruction. Design Clinical practice guideline underpinned by systematic review and expert consensus. Data sources A multidisciplinary working group and steering group systematically reviewed the literature and wrote the guideline. MEDLINE and the Cochrane Library were searched for meta-analyses, systematic reviews, randomised controlled trials and prospective cohort studies published between January 1990 and June 2015. Eligibility criteria for selecting studies Included literature must have addressed 1 of 9 predetermined clinical topics: (1) preoperative predictors for postoperative outcome, (2) effectiveness of physical therapy, (3) open and closed kinetic chain quadriceps exercises, (4) strength and neuromuscular training, (5) electrostimulation and electromyographic feedback, (6) cryotherapy, (7) measurements of functional performance, (8) return to play and (9) risk for reinjury. Summary Ninety studies were included as the basis for the evidence statement. Rehabilitation after ACL injury should include a prehabilitation phase and 3 criterion-based postoperative phases: (1) impairment-based, (2) sport-specific training and (3) return to play. A battery of strength and hop tests, quality of movement and psychological tests should be used to guide progression from one rehabilitation stage to the next. Postoperative rehabilitation should continue for 9–12 months. To assess readiness to return to play and the risk for reinjury, a test battery, including strength tests, hop tests and measurement of movement quality, should be used.

Biomaterials in search of a meniscus substitute.

The menisci fulfill key biomechanical functions in the tibiofemoral (knee) joint. Unfortunately meniscal injuries are quite common and most often treated by (partial) meniscectomy. However, some patients experience enduring symptoms, and, more importantly, it leads to an increased risk for symptomatic osteoarthritis. Over the past decades, researchers have put effort in developing a meniscal substitute able to prevent osteoarthritis and treat enduring clinical symptoms. Grossly, two categories of substitutes are observed: First, a resorbable scaffold mimicking biomechanical function which slowly degrades while tissue regeneration and organization is promoted. Second, a non resorbable, permanent implant which mimics the biomechanical function of the native meniscus. Numerous biomaterials with different (material) properties have been used in order to provide such a substitute. Nevertheless, a clinically applicable cartilage protecting material is not yet emerged. In the current review we provide an overview, and discuss, these different materials and extract recommendations regarding material properties for future developmental research.

Medial open wedge high tibial osteotomy: can delayed or nonunion be predicted?

BackgroundThe opening wedge approach to high tibial osteotomy (HTO) is perceived to have some advantages relative to the closing wedge approach but it may be associated with delayed and nonunions. Because nonunions evolve over months, it would be advantageous to be able to identify risk factors for and early predictors of nonunion after medial opening wedge HTO.Questions/purposesWe sought to determine whether (1) preoperatively identifiable patient factors, including tobacco use, body mass index > 30 kg/m2, and degree of correction, are associated with nonunion, and (2) a modified Radiographic Union Score for Tibial Fractures (RUST) score, taken at 6 weeks and 3 months, would be predictive for delayed or nonunion after medial opening wedge HTO.MethodsThe medical records and radiographs of 185 patients, 21 bilateral cases, treated with a medial open wedge HTO using the TomoFix® device were retrospectively evaluated. For all patients, demographic data regarding risk factors were collected from their records. Diagnosis for delayed or nonunion was already done earlier for standard medical care by the orthopaedic surgeon based on clinical and radiographic grounds. For the retrospective radiographic evaluation, a modified RUST score was used in which each tibial cortex is scored by one observer. Logistic regression analysis was used to identify preoperative and postoperative predictive factors for developing delayed or nonunion. In the series, a total of 19 patients (9.2%) developed clinically delayed/nonunion of whom 10 patients (4.9%) developed a nonunion.ResultsSmoking was identified as a risk factor for developing delayed/nonunion (19% for smokers versus 5.4% for nonsmokers; p = 0.005; odds ratio, 4.1; 95% confidence interval, 1.5–10.7). By contrast, body mass index, lateral cortical hinge fracture, age, infection, and degree of correction were not risk factors. Patients with delayed/nonunion had lower RUST scores at all time points when a radiograph was taken compared with the total study group.ConclusionsThe RUST score at 6 weeks and 3 months after surgery and the use of tobacco were identified as predictive factors for development of delayed union and nonunion after open wedge HTO. Based on these results, we now actively try to stop patients from smoking and these data are helpful in doing that. The RUST score may be of use to identify which patients are at risk for developing a delayed union so that interventions may be offered earlier in the course of care.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Platelet-Rich Plasma Can Replace Fetal Bovine Serum in Human Meniscus Cell Cultures

Concerns over fetal bovine serum (FBS) limit the clinical application of cultured tissue-engineered constructs. Therefore, we investigated if platelet-rich plasma (PRP) can fully replace FBS for meniscus tissue engineering purposes. Human PRP and platelet-poor plasma (PPP) were isolated from three healthy adult donors. Human meniscal fibrochondrocytes (MFCs) were isolated from resected tissue after a partial meniscectomy on a young patient. Passage-4 MFCs were cultured in monolayer for 24 h, and 3 and 7 days. Six different culture media were used containing different amounts of either PRP or PPP and compared to a medium containing 10% FBS. dsDNA was quantified, and gene expression levels of collagen types I and II and aggrecan were measured at different time points with quantitative polymerase chain reaction in the cultured MFCs. After 7 days, the dsDNA quantity was significantly higher in MFCs cultured in 10% and 20% PRP compared to the other PRP and PPP conditions, but equal to 10% FBS. Collagen type I expression was lower in MFCs cultured with medium containing 5% PRP, 10% and 20% PPP compared to FBS. When medium with 10% PRP or 20% PRP was used, expressions were not significantly different from medium containing 10% FBS. Collagen type II expression was absent in all medium conditions. Aggrecan expression did not show differences between the different media used. However, after 7 days a higher aggrecan expression was measured in most culture conditions, except for 5% PRP, which was similar compared to FBS. Statistical significance was found between donors at various time points in DNA quantification and gene expression, but the same donors were not statistically different in all conditions. At 7 days cell cultured with 10% PRP and 20% PRP showed a higher density, with large areas of clusters, compared to other conditions. In an MFC culture medium, FBS can be replaced by 10% PRP or 20% PRP without altering proliferation and gene expression of human MFCs.

In Vivo Performance of a Novel, Anatomically Shaped, Total Meniscal Prosthesis Made of Polycarbonate Urethane: A 12-Month Evaluation in Goats

Background: Injury or loss of the meniscus generally leads to degenerative osteoarthritic changes in the knee joint. However, the treatment options for symptomatic patients with total meniscectomy are limited. Therefore, we developed a novel, anatomically shaped, total meniscal implant made of polycarbonate urethane. Purpose: To evaluate the in vivo performance of this novel total meniscal implant. The assessment particularly focused on the implant’s response to long-term physiological loading in a goat model and its chondroprotective capacity in comparison to clinically relevant controls. Study Design: Controlled laboratory study. Methods: Surgery was performed to the stifle joint of 26 female Saanen goats, subdivided into 4 groups: implant, allograft, total meniscectomy, and sham surgery. The sham group’s contralateral joints served as nonoperated controls. After 12 months of follow-up, investigators evaluated implant wear, deformation, and the histopathological condition of the synovium and cartilage. Results: Wear of the implant’s articulating surfaces was minimal, which was confirmed by the absence of wear particles in the synovial fluid. Implant deformation was limited. However, one implant failed by complete tearing of the posterior horn extension. No differences in cartilage histopathological condition were observed for the implant, allograft, and meniscectomy groups. However, locally, the cartilage scores for these groups were significantly worse than those of the nonoperated controls. Conclusion: Whereas this study demonstrated that the novel implant is resistant to wear and that deformation after 12 months of physiological loading is acceptable, reinforcement of the implant horns is necessary to prevent horn failure. Although the implant could not protect the cartilage from developing degenerative changes, the progression of damage was similar in the allograft group. Clinical Relevance: This novel polycarbonate urethane implant may have the potential to become an alternative treatment for symptomatic patients with total meniscectomy.

Successful Salvage of a Recurrently Dislocating Oxford Medial Unicompartmental Bearing

Dislocation of the bearing of the Oxford medial unicompartmental arthroplasty is a rare but serious complication. We report the case of a 48-year-old woman with a classic anteromedial arthritis who had 2 bearing dislocations within the first 3 months after index surgery. These were attributable to posterior bony impingement of the bearing against a small retained osteophyte. After arthroscopic resection of the osteophyte, she has retained her original components with no further dislocations or signs of impending failure 7 years later. This case report emphasizes the importance of osteophyte removal from the back of the femoral condyle during an Oxford unicompartmental arthroplasty.