Antibiotic cement coating in orthopedic surgery: a systematic review of reported clinical techniques.

BACKGROUND: Antibiotic-containing cement and bone graft substitute-coated orthopedic implants provide the advantages of simultaneous local antibiotic delivery and internal stable fixation, aiding in both infection eradication and osseous healing. Standardized protocols pertaining to implant coating techniques in various clinical and particularly intraoperative settings are scarce, and available literature is limited. This systematic review aims to provide a summary of the available current literature reporting on custom-made coating techniques of orthopedic implants, indications, outcomes, and associated complications in clinical use. METHODS: A systematic search of the literature in PubMed, Medline, Embase, and Cochrane Library databases was performed in accordance with PRISMA guidelines. Articles reporting specifically on custom-made coating techniques of orthopedic implants in a clinical setting were eligible. RESULTS: A total of 41 articles with a cumulative total number of 607 cases were included. Indications for treatment mostly involved intramedullary infections after previous plate osteosynthesis or nailing. A variety of implants ranging from intramedullary nails, plates, wires, and rods served as metal cores for coating. Polymethylmethacrylate (PMMA) bone cement was most commonly used, with vancomycin as the most frequently added antibiotic additive. Chest tubes and silicone tubes were most often used to mold. Common complications are cement debonding and breakage of the metallic implant. CONCLUSION: Adequate coating techniques can reduce the burden of treatment and be associated with favorable outcomes. Lack of general consensus and heterogeneity in the reported literature indicate that the perfect all-in-one implant coating method is yet to be found. Further efforts to improve implant coating techniques are warranted. LEVEL OF EVIDENCE: III.

The Inverse Spacer-A Novel, Safe, and Cost-Effective Approach in Routine Procedures for Revision Knee Arthroplasty.

BACKGROUND: A major disadvantage of current spacers for two-stage revision total knee arthroplasty (R-TKA) is the risk of (sub-) luxation during mobilization in the prosthesis-free interval, limiting their clinical success with detrimental consequences for the patient. The present study introduces a novel inverse spacer, which prevents major complications, such as spacer (sub-) luxations and/or fractures of spacer or bone. METHODS: The hand-made inverse spacer consisted of convex tibial and concave femoral components of polymethylmethacrylate bone cement and was intra-operatively molded under maximum longitudinal tension in 5° flexion and 5° valgus position. Both components were equipped with a stem for rotational stability. This spacer was implanted during an R-TKA in 110 knees with diagnosed or suspected periprosthetic infection. Postoperative therapy included a straight leg brace and physiotherapist-guided, crutch-supported mobilization with full sole contact. X-rays were taken before and after prosthesis removal and re-implantation. RESULTS: None of the patients experienced (sub-) luxations/fractures of the spacer, periprosthetic fractures, or soft tissue compromise requiring reoperation. All patients were successfully re-implanted after a prosthesis-free interval of 8 weeks, except for three patients requiring an early exchange of the spacer due to persisting infection. In these cases, the prosthetic-free interval was prolonged for one week. CONCLUSION: The inverse spacer in conjunction with our routine procedure is a safe and cost-effective alternative to other articulating or static spacers, and allows crutch-supported sole contact mobilization without major post-operative complications. Maximum longitudinal intra-operative tension in 5° flexion and 5° valgus position appears crucial for the success of surgery.

Thickness of the Stifle Joint Articular Cartilage in Different Large Animal Models of Cartilage Repair and Regeneration.

OBJECTIVE: Regulatory guidelines for preclinical cartilage repair studies suggest large animal models (e.g., sheep, goat, [mini]-pig, or horse) to obtain results representative for humans. However, information about the 3-dimensional thickness of articular cartilage at different implantation sites in these models is limited. DESIGN: To identify the most suitable site for experimental surgery, cartilage thickness at the medial femoral condyle (MFC), lateral femoral condyle (LFC), and trochlea in ovine, caprine, and porcine cadaver stifle joints was systematically measured using hematoxylin-eosin staining of 6 µm paraffin sections and software-based image analysis. RESULTS: Regarding all ventral-dorsal regions of the MFC, goat showed the thickest articular cartilage (maximal mean thickness: 1299 µm), followed by sheep (1096 µm) and mini-pig (604 µm), with the highest values in the most ventral and dorsal regions. Also for the LFC, the most ventral regions showed the thickest cartilage in goat (maximal mean thickness: 1118 µm), followed by sheep (678 µm) and mini-pig (607 µm). Except for the mini-pig, however, the cartilage thickness on the LFC was consistently lower than that on the MFC. The 3 species also differed along the transversal measuring points on the MFC and LFC. In contrast, there were no consistent differences for the regional cartilage thickness of the trochlea among goat and sheep (≥780 µm) and mini-pig (≤500 µm). CONCLUSIONS: Based on their cartilage thickness, experimental defects on goat and sheep MFC may be viable options for preclinical cartilage repair studies, in addition to well-established horse models.

Systematic Postoperative Assessment of a Minimally-Invasive Sheep Model for the Treatment of Osteochondral Defects.

To assess the clinical course of a sheep stifle joint model for osteochondral (OC) defects, medial femoral condyles (MFC) were exposed without patella luxation using medial parapatellar skin (3-4 cm) and deep incisions (2-3 cm). Two defects (7 mm diameter; 10 mm depth; OC punch) were left empty or refilled with osteochondral autologous transplantation cylinders (OATS) and explanted after six weeks. Incision-to-suture time, anesthesia time, and postoperative wound or impairment scores were compared to those in sham-operated animals. Implant performance was assessed by X-ray, micro-computed tomography, histology, and immunohistology (collagens 1, 2; aggrecan). There were no surgery-related infections or patellar luxations. Operation, anesthesia, and time to complete stand were short (0.5, 1.4, and 1.5 h, respectively). The wound trauma score was low (0.4 of maximally 4; day 7). Empty-defect and OATS animals reached an impairment score of 0 significantly later than sham animals (7.4 and 4.0 days, respectively, versus 1.5 days). Empty defects showed incomplete healing and dedifferentiation/heterotopic differentiation; OATS-filled defects displayed advanced bone healing with remaining cartilage gaps and orthotopic expression of bone and cartilage markers. Minimally-invasive, medial parapatellar surgery of OC defects on the sheep MFC allows rapid and low-trauma recovery and appears well-suited for implant testing.

Comparison of Near-Infrared Spectroscopy with Needle Indentation and Histology for the Determination of Cartilage Thickness in the Large Animal Model Sheep.

The suitability of near-infrared spectroscopy (NIRS) for non-destructive measurement of cartilage thickness was compared with the gold standard needle indentation. A combination of NIRS and biomechanical indentation (NIRS-B) was used to address the influence of varying loads routinely applied for hand-guided NIRS during real-life surgery on the accuracy of NIRS-based thickness prediction. NIRS-B was performed under three different loading conditions in 40 osteochondral cylinders from the load-bearing area of the medial and lateral femur condyle of 20 cadaver joints (left stifle joints; female Merino sheep; 6.1 ± 0.6 years, mean ± standard error of the mean). The cartilage thickness measured by needle indentation within the region analyzed by NIRS-B was then compared with cartilage thickness prediction based on NIRS spectral data using partial least squares regression. NIRS-B repeat measurements yielded highly reproducible values concerning force and absorbance. Separate or combined models for the three loading conditions (the latter simulating load-independent measurements) resulted in models with optimized quality parameters (e.g., coefficients of determination R2 between 92.3 and 94.7) and a prediction accuracy of < 0.1 mm. NIRS appears well suited to determine cartilage thickness (possibly in a hand-guided, load-independent fashion), as shown by high reproducibility in repeat measurements and excellent reliability compared with tissue-destructive needle indentation. This may provide the basis for non-destructive, intra-operative assessment of cartilage status quo and fine-tuning of repair procedures.

The GDF5 mutant BB-1 enhances the bone formation induced by an injectable, poly(l-lactide-co-glycolide) acid (PLGA) fiber-reinforced, brushite-forming cement in a sheep defect model of lumbar osteopenia.

BACKGROUND CONTEXT: Targeted delivery of osteoinductive bone morphogenetic proteins (eg, GDF5) in bioresorbable calcium phosphate cement (CPC), potentially suitable for vertebroplasty and kyphoplasty of osteoporotic vertebral fractures, may be required to counteract augmented local bone catabolism and to support complete bone regeneration. The biologically optimized GDF5 mutant BB-1 may represent an attractive drug candidate for this purpose. PURPOSE: The aim of the current study was to test an injectable, poly(l-lactide-co-glycolide) acid (PLGA) fiber-reinforced, brushite-forming CPC containing low-dose BB-1 in a sheep lumbar osteopenia model. STUDY DESIGN/ SETTING: This is a prospective experimental animal study. METHODS: Bone defects (diameter 5 mm) were generated in aged, osteopenic female sheep and were filled with fiber-reinforced CPC alone (L4; CPC+fibers) or with CPC containing different dosages of BB-1 (L5; CPC+fibers+BB-1; 5, 100, and 500 µg BB-1; n=6 each). The results were compared with those of untouched controls (L1). Three and 9 months after the operation, structural and functional effects of the CPC (±BB-1) were analyzed ex vivo by measuring (1) bone mineral density (BMD); (2) bone structure, that is, bone volume/total volume (BV/TV) (assessed by micro-CT and histomorphometry), trabecular thickness (Tb.Th), and trabecular number (Tb.N); (3) bone formation, that is, osteoid volume/bone volume (OV/BV), osteoid surface/bone surface (OS/BS), osteoid thickness, mineralizing surface/bone surface (MS/BS), mineral apposition rate, and bone formation rate/bone surface; (4) bone resorption, that is, eroded surface/bone surface; and (5) compressive strength. RESULTS: Compared with untouched controls (L1), CPC+fibers (L4) and/or CPC+fibers+BB-1 (L5) significantly improved all parameters of bone formation, bone resorption, and bone structure. These effects were observed at 3 and 9 months, but were less pronounced for some parameters at 9 months. Compared with CPC without BB-1, additional significant effects of BB-1 were demonstrated for BMD, bone structure (BV/TV, Tb.Th, and Tb.N), and bone formation (OS/BS and MS/BS). The BB-1 effects on bone formation at 3 and 9 months were dose dependent, with 100 µg as the potentially optimal dosage. CONCLUSIONS: BB-1 significantly enhanced the bone formation induced by a PLGA fiber-reinforced CPC in sheep lumbar osteopenia. A single local dose as low as 100 µg BB-1 was sufficient to augment middle- to long-term bone formation. A CPC containing the novel GDF5 mutant BB-1 may thus represent an alternative to the bioinert, supraphysiologically stiff polymethylmethacrylate cement presently used to treat osteoporotic vertebral fractures by vertebroplasty and kyphoplasty.

Erratum: Author's name correction.

[This corrects the article on p. 5 in vol. 6, PMID: 27299113.].

Surgical Preparation for Articular Cartilage Regeneration in the Osteoarthritic Knee Joint.

PURPOSE: Autologous chondrocyte implantation (ACI) is a treatment option even in early osteoarthritis (OA). Surgical preparation for ACI should avoid penetration of the subchondral bone plate to prevent hemorrhage, fibrin clot formation, and subsequent activation of the inflammatory response. HYPOTHESIS: Current surgical procedures with ring curettes preserve the integrity of the subchondral bone plate, even in patients with OA. METHODS: Subchondral femoral bone plates ( n = 40) of OA knees undergoing total knee arthroplasty were prepared in vivo using standard, non-brute-force debridement for ACI. To approach regular wear/early OA, only cartilage with maximally grade 3A International Cartilage Repair Society score was prepared. Effects were analyzed by light microscopy. RESULTS: In 87.5% of the specimens (35/40), standard debridement did not violate the tide mark, except for occasional minor openings with a smooth edge (diameter approximately 20 µm). In contrast, 5/40 samples (12.5%) showed one large area with a missing bone plate and an open bone marrow space. Twenty-eight specimens (70%) showed at least remnants of uncalcified cartilage. CONCLUSION: On the basis of size/fine structure, the occasional minor openings are likely due to increased vascular penetration through the tide mark in the pathologically altered bone-cartilage interface in OA. The consequences of limited hemorrhage through minor openings or selected large defects following in vivo debridement are still unknown. Thus, standard debridement appears suitable for cartilage regeneration even in OA defects.

Low-dose BMP-2 is sufficient to enhance the bone formation induced by an injectable, PLGA fiber-reinforced, brushite-forming cement in a sheep defect model of lumbar osteopenia.

BACKGROUND CONTEXT: Bioresorbable calcium phosphate cement (CPC) may be suitable for vertebroplasty/kyphoplasty of osteoporotic vertebral fractures. However, additional targeted delivery of osteoinductive bone morphogenetic proteins (BMPs) in the CPC may be required to counteract the augmented local bone catabolism and support complete bone regeneration. PURPOSE: This study aimed at testing an injectable, poly (l-lactide-co-glycolide) acid (PLGA) fiber-reinforced, brushite-forming cement (CPC) containing low-dose bone morphogenetic protein BMP-2 in a sheep lumbar osteopenia model. STUDY DESIGN/ SETTING: This is a prospective experimental animal study. METHODS: Bone defects (diameter 5 mm) were generated in aged, osteopenic female sheep and filled with fiber-reinforced CPC alone (L4; CPC+fibers) or with CPC containing different dosages of BMP-2 (L5; CPC+fibers+BMP-2; 1, 5, 100, and 500 µg BMP-2; n=5 or 6 each). The results were compared with those of untouched controls (L1). Three and 9 months after the operation, structural and functional effects of the CPC (±BMP-2) were analyzed ex vivo by measuring (1) bone mineral density (BMD); (2) bone structure, that is, bone volume/total volume (assessed by micro-computed tomography [micro-CT] and histomorphometry), trabecular thickness, and trabecular number; (3) bone formation, that is, osteoid volume/bone volume, osteoid surface/bone surface, osteoid thickness, mineralizing surface/bone surface, mineral apposition rate, and bone formation rate/bone surface; (4) bone resorption, that is, eroded surface/bone surface; and (5) compressive strength. RESULTS: Compared with untouched controls (L1), CPC+fibers (L4) and/or CPC+fibers+BMP-2 (L5) significantly improved all parameters of bone formation, bone resorption, and bone structure. These effects were observed at 3 and 9 months, but were less pronounced for some parameters at 9 months. Compared with CPC without BMP-2, additional significant effects of BMP-2 were demonstrated for bone structure (bone volume/total volume, trabecular thickness, trabecular number) and formation (osteoid surface/bone surface and mineralizing surface/bone surface), as well as for the compressive strength. The BMP-2 effects on bone formation at 3 and 9 months were dose-dependent, with 5-100 µg as the optimal dosage. CONCLUSIONS: BMP-2 significantly enhanced the bone formation induced by a PLGA fiber-reinforced CPC in sheep lumbar osteopenia. A single local dose as low as ≤100 µg BMP-2 was sufficient to augment middle to long-term bone formation. The novel CPC+BMP-2 may thus represent an alternative to the bioinert, supraphysiologically stiff polymethylmethacrylate cement presently used to treat osteoporotic vertebral fractures by vertebroplasty/kyphoplasty.

GDF5 significantly augments the bone formation induced by an injectable, PLGA fiber-reinforced, brushite-forming cement in a sheep defect model of lumbar osteopenia.

BACKGROUND CONTEXT: Biodegradable calcium phosphate cement (CPC) represents a promising option for the surgical treatment of osteoporotic vertebral fractures. Because of augmented local bone catabolism, however, additional targeted delivery of bone morphogenetic proteins with the CPC may be needed to promote rapid and complete bone regeneration. PURPOSE: In the present study, an injectable, poly(l-lactide-co-glycolide) acid (PLGA) fiber-reinforced, brushite-forming cement (CPC) containing the bone morphogenetic protein GDF5 was tested in a sheep lumbar osteopenia model. STUDY DESIGN/SETTING: This is a prospective experimental animal study. METHODS: Defined bone defects (diameter 5 mm) were placed in aged, osteopenic female sheep. Defects were treated with fiber-reinforced CPC alone (L4; CPC+fibers) or with CPC containing different dosages of GDF5 (L5; CPC+fibers+GDF5; 1, 5, 100, and 500 µg GDF5; n=5 or 6 each). The results were compared with those of untouched controls (L1). Three and 9 months postoperation, structural and functional effects of the CPC (±GDF5) were assessed ex vivo by measuring (1) bone mineral density (BMD); (2) bone structure, that is, bone volume/total volume (assessed by micro-computed tomography and histomorphometry), trabecular thickness, and trabecular number; (3) bone formation, that is, osteoid volume/bone volume, osteoid surface/bone surface, osteoid thickness, mineralized surface/bone surface, mineral apposition rate, and bone formation rate/bone surface; (4) bone resorption, that is, eroded surface/bone surface; and (5) compressive strength. RESULTS: Compared with untouched controls (L1), both CPC+fibers (L4) and CPC+fibers+GDF5 (L5) numerically or significantly improved all parameters of bone formation, bone resorption, and bone structure. These significant effects were observed both at 3 and 9 months, but for some parameters they were less pronounced at 9 months. Compared with CPC without GDF5, additional significant effects of CPC with GDF5 were demonstrated for BMD and parameters of bone formation and structure (bone volume/total volume, trabecular thickness, and trabecular number, as well as mineralized surface/bone surface). The GDF5 effects were dose-dependent (predominantly in the 5-100 µg range) at 3 and 9 months. CONCLUSIONS: GDF5 significantly enhanced the bone formation induced by a PLGA fiber-reinforced CPC in sheep lumbar osteopenia. The results indicated that a local dose as low as ≤100 µg GDF5 may be sufficient to augment middle to long-term bone formation. The novel CPC+GDF5 combination may thus qualify as an alternative to the bioinert, supraphysiologically stiff poly(methyl methacrylate) cement currently applied for vertebroplasty/kyphoplasty of osteoporotic vertebral fractures.

Isolated Acute Exertional Compartment Syndrome (AECS) of the Extensor Carpi Ulnaris.

INTRODUCTION: Only two cases of an isolated compartment syndrome of the extensor carpi ulnaris have been described previously [1,2]. In both cases, the onset was acute. In the first case, histological examination revealed no necrosis. The second case was regarded to be due to a previously unknown anatomic variation and no necrotic tissue was recognized upon gross examination. This case report describes a third case of an isolated acute exertional compartment syndrome (AECS) of the extensor carpi ulnaris muscle with focal areas of necrotic tissue. CASE REPORT: We report the third case of an isolated AECS of the extensor carpi ulnaris muscle. A 35 year-old left-handed man, a motor mechanic by profession, presented to the emergency department with excruciating pain at the ulnar side of the left dorsal forearm. The previous day, he had repetitively used a sliding hammer with his left arm. Since then he had experienced severe pain despite the use of over-the-counter non-steroidal anti-inflammatory drugs. Here, in contrast to the previously reported cases, the histological examination revealed focal areas of necrotic tissue. No anatomic variations were found during surgical decompression. Postoperatively, the patient had complete pain relief and return of function. CONCLUSION: This report again indicates that the extensor carpi ulnaris is especially prone to develop the AECS syndrome and raises the question whether involvement of the other extensor muscles may rather be secondary to the excessive swelling of the extensor carpi ulnaris and not to strenuous exercise. This should be taken into consideration when humans load their forearm repeatedly during heavy labor or sports. In addition, we are showing that even with histologically confirmed areas of partial muscle necrosis the patient can return to normal muscle function.

First-time systematic postoperative clinical assessment of a minimally invasive approach for lumbar ventrolateral vertebroplasty in the large animal model sheep.

BACKGROUND CONTEXT: Large animal models are highly recommended for meaningful preclinical studies, including the optimization of cement augmentation for vertebral body defects by vertebroplasty/kyphoplasty. PURPOSE: The aim of this study was to perform a systematic characterization of a strictly minimally invasive in vivo large animal model for lumbar ventrolateral vertebroplasty. STUDY DESIGN/ SETTING: This is a prospective experimental animal study. METHODS: Lumbar defects (diameter 5 mm; depth approximately 14 mm) were created by a ventrolateral percutaneous approach in aged, osteopenic, female sheep (40 Merino sheep; 6-9 years; 68-110 kg). L1 remained untouched, L2 was left with an empty defect, and L3 carried a defect injected with a brushite-forming calcium phosphate cement (CPC). Trauma/functional impairment, surgical techniques (including drill sleeve and working canula with stop), reproducibility, bone defects, cement filling, and functional cement augmentation were documented by intraoperative incision-to-suture time and X-ray, postoperative trauma/impairment scores, and ex vivo osteodensitometry, microcomputed tomography (CT), histology, static/fluorescence histomorphometry, and biomechanical testing. RESULTS: Minimally invasive vertebroplasty resulted in short operation times (28±2 minutes; mean±standard error of the mean) and X-ray exposure (1.59±0.12 minutes), very limited local trauma (score 0.00±0.00 at 24 hours), short postoperative recovery (2.95±0.29 hours), and rapid decrease of the postoperative impairment score to 0 (3.28±0.36 hours). Reproducible defect creation and cement filling were documented by intraoperative X-ray and ex vivo conventional/micro-CT. Vertebral cement augmentation and osteoconductivity of the CPC was verified by osteodensitometry (CPC>control), micro-CT (CPC>control and empty defect), histology/static histomorphometry (CPC>control and empty defect), fluorescence histomorphometry (CPC>control; all p<.05 for 3 and 9 months), and compressive strength measurements (CPC numerically higher than control; 102% for 3 months and 110% for 9 months). CONCLUSIONS: This first-time systematic clinical assessment of a minimally invasive, ventrolateral, lumbar vertebroplasty model in aged, osteopenic sheep resulted in short operation times, rapid postoperative recovery, and high experimental reproducibility. This model represents an optimal basis for standardized evaluation of future studies on vertebral augmentation with resorbable and osteoconductive CPC.

Evaluation of antibiotic-impregnated microspheres for the prevention of implant-associated orthopaedic infections.

BACKGROUND: Prevention of infection associated with uncemented orthopaedic implants could lead to improved implant stability and better patient outcomes. We hypothesized that coating porous metal implants with antibiotic-containing microspheres would prevent infections in grossly contaminated wounds. METHODS: Bioresorbable polymer microspheres containing tobramycin were manufactured and pressed into porous metal cylinders that were then implanted into radial defects in rabbits. Control implants that did not contain antibiotic microspheres were also implanted into the contralateral limbs. Each implant was then contaminated with Staphylococcus aureus prior to closure of the wound. The animal was euthanized after clinical signs of infection appeared, or at two weeks after surgery. Periprosthetic tissue was cultured for the presence of S. aureus, and integration of the implant with the surrounding bone was measured. RESULTS: The antibiotic microspheres successfully prevented infection in 100% of the eleven limbs with treated implants, which represented a significant improvement (p = 0.004) compared with the infection rate of 64% (seven of eleven) for the limbs with control implants. Implant integration averaged 38.87% ± 12.69% in the fifteen uninfected limbs, which was significantly better (p = 0.012) than the average of 19.46% ± 14.49% in the seven infected limbs. CONCLUSIONS: The antibiotic delivery system successfully prevented infection in 100% of the cases studied, resulting in an increase in implant integration. CLINICAL RELEVANCE: Antibiotic delivery utilizing the system described here may be effective in preventing implant-associated infections after orthopaedic surgery and increasing the longevity of orthopaedic implants.

Primary bone lymphomas thought to be osteomyelitis urgently demand a rapid diagnosis in bone pathology.

We describe in detail three cases of primary bone lymphoma (PBL), initially treated as osteomyelitis of unknown etiology. These cases show which difficulties can occur with diagnosing this entity and highlight the urgent need for rapid diagnostic results in the field of bone pathology. Case 1: A 22-year-old man with the very rare diagnosis of precursor B-lymphoblastic lymphoma in the tibia (previously published). Case 2: A 13-year-old boy with an anaplastic large cell lymphoma of the "os pubis". With initial diagnosis pointing to multifocal osteomyelitis, histology of the left iliac crest revealed a florid/chronic osteomyelitis. During clinical regression with a new osteolytic lesion, he received treatment for chronic recurrent multifocal osteomyelitis. Case 3: A 60-year-old man with an anaplastic large cell lymphoma of the right sacrum, accompanied by a putrid, florid/chronic osteomyelitis. At first, an incisional biopsy revealed a florid/chronic osteomyelitis-only.

Surgical preparation for articular cartilage regeneration without penetration of the subchondral bone plate: in vitro and in vivo studies in humans and sheep.

BACKGROUND: To prevent hemorrhage, fibrin clot formation, and subsequent activation of the inflammatory response, surgical preparation for articular cartilage regeneration should avoid penetration of the subchondral bone plate. HYPOTHESIS: Current surgical procedures with ring curettes do not violate the subchondral bone plate. STUDY DESIGN: Controlled laboratory study. METHODS: The subchondral bone plates of normal human (n = 5) or sheep (n = 12) cadaver femoral condyles were prepared in vitro using either traditional debridement for autologous chondrocyte implantation/transplantation (ACI/ACT) or a modified approach aimed at deliberately violating the subchondral bone plate (ie, brute force). Effects were analyzed by light microscopy. In addition, subchondral bone plates of osteoarthritic (OA) human knees undergoing total knee arthroplasty (n = 5) or normal sheep knees (n = 5) were prepared in vivo. To approximate normal/regular wear, in humans, only OA samples with maximally grade 3A (International Cartilage Repair Society score) were used. RESULTS: In both human and sheep (in vitro), no penetration of the subchondral bone plate was observed by either standard preparation or brute force. In vivo, standard preparation of human or sheep knees also did not violate the tidemark line. Human and sheep specimens prepared by brute force, however, occasionally showed areas with an open bone marrow space. CONCLUSION: Traditional debridement techniques for ACI/ACT using a ring curette do not violate the normal subchondral bone plate in vitro or in vivo. Even in OA knee joints, the bone plate is only violated by brute force. Therefore, the standard technique appears suitable for studies on cartilage regeneration in cases of traumatic and possibly even osteoarthritic defects. CLINICAL RELEVANCE: The described surgical preparation technique is the traditional debridement technique for the ACI/ACT. The classic indication for the ACI/ACT is an articular cartilage injury, common in athletes.