Review of K.H. Pridie (1959) on "A method of resurfacing osteoarthritic knee joints".

This classic discusses the original publication "A method of resurfacing osteoarthritic knee joints" by Dr K.H. Pridie (1959), where this pioneer surgeon described a newly developed method for the treatment of osteoarthritic joint surfaces of the knee, which he named subchondral drilling. This short and concise 11-line publication appeared in the Proceedings of the Congress of the British Orthopaedic Association. It has generated 464 citations since 1959, becoming part of the hundred most-cited publications in knee research. Pridie introduced in clinical experimentation the entity of Marrow Stimulation Techniques to liberate mesenchymal stem cells from cancellous bone. He was aware that the results induced, in terms of quality of the regrown tissue, was limited and "only" fibrocartilage. His idea might have been raised from the work of numerous animal researchers who confirmed repeatedly since 1905 that cartilage needed an osseous perforation to heal. Although the past 60 years brought modifications from the technique described in the original article, the concept of marrow stimulation introduced by Pridie remains the most frequently used in cartilage repair surgery today.

Stable clinical long term results after AMIC in the aligned knee.

INTRODUCTION: The aim of this study was to report a long-term follow-up of patients treated with autologous matrix-induced chondrogenesis (AMIC) for full-thickness chondral and osteochondral defects of the femoral condyle or patella combined with the correction of lower limb malalignment or patellar tracking if indicated. METHODS: Thirty-three patients (thirty-four knees) were treated surgically for chondral and osteochondral cartilage defects of the knee joint. Regarding the origin of the lesion, patients were divided into three groups. Chondral lesions were observed in the patella (cP group) in fifteen patients, whereas eight patients demonstrated a femoral condylar location (cF group). Eleven patients presented with osteochondritis dissecans of the femur (ocF group). Associated procedures involving realignment of the patella, osteotomy around the knee, or cancellous bone grafting were performed when necessary. The mean size of the lesions was 2.8 ± 1.6 cm2, and the mean patient age was 37.1 ± 11.9 years. To evaluate the clinical outcomes, the Lysholm score and the VAS pain score were imposed, as well as the reoperation rate. RESULTS: After an average of 9.3 ± 1 years, follow-up was completed in 79% of the patients. Two patients from the cohort received a total knee prosthesis. The primary outcome measures (Lysolm and VAS pain) at 9-year follow-up were 85 ± 13 for the Lysholm score and 1.9 ± 1.6 for the VAS score in the entire analyzed population. Compared to the preoperative values (Lysholm 56 ± 19, VAS 5.8 ± 2.4) and the 2-year results (Lysholm 85 ± 16, VAS 2.0 ± 2.1), there was significant improvement in the first 2 years after intervention and a stable course in the long-term observation. The same was observed in the cP and ocF subgroups, whereas patients of the cF group showed even further improvement. CONCLUSIONS: AMIC showed durable results in aligned knees. The favorable outcome was maintained after an average of 9 years when malalignment of the lower limb and patellar maltracking were corrected. Such data are particularly encouraging for young adult patients who may benefit from a procedure that circumvents early arthroplasty.

Healing of the Acutely Injured Anterior Cruciate Ligament: Functional Treatment with the ACL-Jack, a Dynamic Posterior Drawer Brace.

Background. The injured anterior cruciate ligament (ACL) has a limited healing capacity leading to persisting instability. Hypothesis/Purpose. To study if the application of a brace, producing a dynamic posterior drawer force, after acute ACL injury reduces initial instability. Study Design. Cohort study. Methods. Patients treated with the ACL-Jack brace were compared to controls treated with primary ACL reconstruction und controls treated nonsurgically with functional rehabilitation. Measurements included anterior laxity (Rolimeter), clinical scores (Lysholm, Tegner, and IKDC), and MRI evaluation. Patients were followed up to 24 months. Results. Patients treated with the ACL-Jack brace showed a significant improvement of anterior knee laxity comparable to patients treated with ACL reconstruction, whereas laxity persisted after nonsurgical functional rehabilitation. The failure risk (secondary reconstruction necessary) of the ACL-Jack group was however 21% (18 of 86) within 24 months. Clinical scores were similar in all treatment groups. Conclusion. Treatment of acute ACL tears with the ACL-Jack brace leads to improved anterior knee laxity compared to nonsurgical treatment with functional rehabilitation.

The Role of Cells in Meniscal Guided Tissue Regeneration: A Proof of Concept Study in a Goat Model.

OBJECTIVE: Successful repair of defects in the avascular zone of meniscus remains a challenge in orthopedics. This proof of concept study aimed to investigate a guided tissue regeneration approach for treatment of tears in meniscus avascular zone in a goat model. DESIGN: Full-depth longitudinal tear was created in the avascular zone of the meniscus and sutured. In the two treatment groups, porcine collagen membrane was wrapped around the tear without (CM) or with injection of expanded autologous chondrocytes (CM+cells), whereas in the control group the tear remained only sutured. Gait recovery was evaluated during the entire follow-up period. On explantation at 3 and 6 months, macroscopic gross inspection assessed healing of tears, degradation of collagen membrane, potential signs of inflammation, and osteoarthritic changes. Microscopic histology scoring criteria were developed to evaluate healing of tears, the cellular response, and the inflammatory response. RESULTS: Gait recovery suggested protective effect of collagen membrane and was supported by macroscopical evaluation where improved tear healing was noted in both treated groups. Histology scoring in CM compared to suture group revealed an increase in tear margins contact, newly formed connective tissue between margins, and cell formations surrounded with new matrix after 3 months yet not maintained after 6 months. In contrast, in the CM+cells group these features were observed after 3 and 6 months. CONCLUSIONS: A transient, short-term guided tissue regeneration of avascular meniscal tears occurred upon application of collagen membrane, whereas addition of expanded autologous chondrocytes supported more sustainable longer term tear healing.

High tibial osteotomy: indications, techniques, and postoperative management.

High tibial osteotomy is a safe and effective treatment for medial compartment arthrosis of the knee accompanied by varus alignment. This procedure has seen increasing use as an adjunct to cartilage restoration procedures, such as autologous chondrocyte and meniscal allograft transplantation, when angular deformity exists. The overall goals of high tibial osteotomy can be accomplished by several different techniques. The main indications for high tibial osteotomy are as a primary treatment for varus gonarthrosis and in conjunction with cartilage restoration procedures, such as autologous chondrocyte implantation or microfracture, where success rates are enhanced by correcting the varus deformity.

ACL reconstruction with physiological graft tension by intraoperative adjustment of the anteroposterior translation to the uninjured contralateral knee.

PURPOSE: Fixation of anterior cruciate ligament (ACL) substitutes with non-physiological anteroposterior translation (APT) worsens outcome. The aim was to present a technique for physiological APT adjustment of the transplant in ACL reconstruction and its outcome at midterm. METHODS: In a consecutive series of 28 patients (age 32 ± 11 years, 24 male), chronic ACL deficiency was treated by bone-patella-tendon-bone reconstruction. Transplant APT was adjusted to that of the contralateral uninjured ACL, measured 3, 6, and 12 months postoperatively using the Rolimeter. At a median follow-up of 5.3 years (3-8 years), 82% of the patients were re-evaluated with APT measurement and using IKDC-, Tegner-, Lysholm-Scores, conventional radiographs and MRI. RESULTS: No differences in APT (mean ± SD) between uninjured and reconstructed knees were observed after adjustment (6 ± 1 versus 6 ± 1 mm, n.s.). Three months postoperatively, a statistically significant increase in APT (7 ± 1 mm) and a further increase at midterm (9 ± 2 mm) were observed. Patients scored "normal" or "nearly normal", respectively, in 79% (IKDC) and 4 (3-9) points (Tegner; median, range) or 89 ± 9 points (Lysholm; mean ± SD). Radiological evaluation showed no, minimal or moderate joint degeneration in 5, 20 and 75% of patients, respectively. MRI confirmed intact ACL transplants in all patients. CONCLUSION: ACL reconstruction using the presented technique was considered successful, as patients did not suffer from subjective instability, radiographic analysis did not provide evidence for graft rupture at midterm. However, APT increase and occurrence of degenerative changes in reconstructed knees at the midterm might not be prevented even by restoration of a physiological APT in ACL reconstruction. The Rolimeter can be used for quick and easy intraoperative indirect control of the applied tension to the ACL transplant by measuring the APT to obtain physiological tensioning resulting in a satisfying outcome at midterm. LEVEL OF EVIDENCE: IV.

Treatment of isolated chondral and osteochondral defects in the knee by autologous matrix-induced chondrogenesis (AMIC).

PURPOSE: The purpose of this study is to evaluate clinical and radiological outcomes of patients treated with autologous matrix-induced chondrogenesis (AMIC) for full-thickness chondral and osteochondral defects of the femoral condyles and patella. METHOD: A retrospective evaluation of clinical and radiographic outcomes of patients treated with AMIC for chondral and osteochondral full-thickness cartilage defects of the knee was performed with a mean follow-up of 28.8 ± 1.5 months (range, 13-51 months). RESULTS: Significant improvements in clinical outcome scores (IKDC, Lysholm, Tegner, and VAS pain score) were noted. The largest improvements were seen in the osteochondral subgroup (mean age 25.9 years), whereas patients treated for chondral defects in the patellofemoral joint and on the femoral condyles improved less. Patients in all groups were generally satisfied with their results. MRI evaluation showed that tissue filling was present but generally not complete or homogenous. CONCLUSIONS: AMIC is a safe procedure and leads to clinical improvement of symptomatic full-thickness chondral and osteochondral defects and to regenerative defect filling. The value of AMIC relative to other cartilage repair procedures and to the natural course remains undefined. LEVEL OF EVIDENCE: Case series, Level IV.

Distal femoral varus osteotomy: problems associated with the lateral open-wedge technique.

INTRODUCTION: Varisation osteotomies on the distal femur are an established treatment method for valgus osteoarthritis of the knee in younger patients. Osteotomy can be done in a lateral open-wedge or medial closed-wedge manner. METHOD: We retrospectively studied 14 patients treated by the lateral open-wedge technique, fixed with the Tomofix plate, with a mean duration of follow-up of 45 ± 3.4 months. RESULTS: We observed often delayed osteotomy healing after 3, 6 and 12 months, no secondary dislocations, and frequent troublesome irritation due to the plate being on the iliotibial band. However, outcome was satisfactory once the osteotomy healed and the plate was removed. CONCLUSION: Based on the often slow healing of the osteotomy and frequent irritation due to the plate, this procedure has been abandoned by the authors, and the medial closing-wedge osteotomy adopted as the alternative treatment.

High tibial valgus osteotomy in unicompartmental medial osteoarthritis of the knee: a retrospective follow-up study over 13-21 years.

PURPOSE: High tibial osteotomy is a well-established method for the treatment of medial unicompartmental osteoarthritis of the knee. METHODS: We analysed retrospectively the long-term outcome of open and closing wedge valgisation high tibial osteotomies. Out of 71 patients, 54 (76%) were available for the study. Survival rates and the influence of the osteotomy type were investigated. Secondary outcome measures were the course of radiological leg axis and osteoarthritis as well as score outcomes. RESULTS: During a median follow-up of 16.5 years (IQR 14.5-17.9; range 13-21), 13 patients (24%) underwent conversion to total knee arthroplasty; the other 41 patients (76%, survivor group) were studied by score follow-up as well as clinical and radiological examinations. Osteotomy survival was of 98% after 5 years, 92% after 10 years and 71% after 15 years. Comparison between open and closing wedge high tibial osteotomy showed no significant difference in survival and score outcome. The median Visual Analogue Score (VAS) was 0 (IQR 0-1; range 0-4), the Satisfaction Index was 80% (IQR 63-89; range 30-100), the median Knee Injury and Osteoarthritis Outcome Score was 71 (IQR 49-82; range 9-100) and the median Western Ontario and McMaster Universities Osteoarthritis index was 84 (IQR 66-96; range 9-100). Radiological evaluation showed only a slight progression of the degree of osteoarthritis following the Kellgren and Lawrence classification. In each case, the axis passed through the healthy compartment or at least through the centre of the knee. CONCLUSION: Open and closing wedge high tibial osteotomies are a successful choice of treatment for unicompartmental degenerative diseases with associated varus in active patients. Survival of both techniques is comparable in our series and is associated with low pain scores, high satisfaction and high activity levels of the survivors.

Biomechanical investigation of an alternative concept to angular stable plating using conventional fixation hardware.

BACKGROUND: Angle-stable locking plates have improved the surgical management of fractures. However, locking implants are costly and removal can be difficult. The aim of this in vitro study was to evaluate the biomechanical performance of a newly proposed crossed-screw concept ("Fence") utilizing conventional (non-locked) implants in comparison to conventional LC-DCP (limited contact dynamic compression plate) and LCP (locking compression plate) stabilization, in a human cadaveric diaphyseal gap model. METHODS: In eight pairs of human cadaveric femora, one femur per pair was randomly assigned to receive a Fence construct with either elevated or non-elevated plate, while the contralateral femur received either an LCP or LC-DCP instrumentation. Fracture gap motion and fatigue performance under cyclic loading was evaluated successively in axial compression and in torsion. Results were statistically compared in a pairwise setting. RESULTS: The elevated Fence constructs allowed significantly higher gap motion compared to the LCP instrumentations (axial compression: p

Association between mechanical axis of the leg and osteochondritis dissecans of the knee: radiographic study on 103 knees.

BACKGROUND: The cause of osteochondritis dissecans (OCD) is unknown, but mechanical factors seem to play a role. PURPOSE: To identify a relationship between localization of OCD and mechanical axis of the leg. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Using bilateral full-leg standing radiographs, we analyzed the position of the mechanical axis of the leg in a group of 93 adolescent and adult patients (103 knees) with OCD of the medial or lateral femoral condyle. RESULTS: The location of OCD and the position of the mechanical axis in the same knee compartment was significantly correlated for both knees with medial (P < .001) as well as lateral (P < .012) compartment OCD. In the medial OCD group, the mean mechanical axis was located in the medial knee compartment (28% medial +/- 2.8%; range, 100% medial to 14% lateral) with a statistically insignificant medial shift with respect to the unaffected side. In lateral OCD, the mean mechanical axis was located laterally (13% lateral +/- 3.9%; range, 13% medial to 60% lateral) with a significant shift from the medial into the lateral knee compartment when comparing unaffected with affected knees. No significant difference was observed between adolescents with open growth plates compared with adults with closed growth plates (P > .05). CONCLUSION: We found an association between medial condyle OCD and varus axis and between lateral condyle OCD and valgus axis. This evokes higher loading of the affected than of the unaffected knee compartment, and therefore, axial alignment may be a cofactor in OCD of the femoral condyles.

Avoiding intraoperative complications in open-wedge high tibial valgus osteotomy: technical advancement.

Open-wedge high tibial osteotomy for varus osteoarthritis of the knee is a successful treatment option, but is associated with potential intraoperative complications, jeopardizing outcome. We describe four technical hints avoiding complications as tibia plateau fracture, lateral hinge dislocation, over- and undercorrection, and unwanted increase of the posterior tibial slope and axial malrotation. The technique, which is primarily based on placing five Kirschner-wires (one for the osteotomy direction, two for the external fixator, and two for rotational and slope control) is simple, reproducible, inexpensive, and readily available.

Infections after high tibial open wedge osteotomy: a case control study.

BACKGROUND AND PURPOSE: High tibial open wedge valgisation osteotomy (HTO) is a widely used procedure for the treatment of unicompartimental osteoarthritis of the knee. Instead of the classical paramedian longitudinal skin incision, some advocate an oblique incision, in order to get a better exposure of the postero-medial aspect of the tibial head, while reducing strain on the soft tissues. Risk factors for surgical site infection were analysed. METHODS: Retrospective analysis of all cases of HTO performed in a single institution between January 2000 and June 2006. RESULTS: A total of 106 patients underwent 110 HTO during the study period. The standard longitudinal incision had been used in 90, oblique incision in 20 cases. Four infections occurred, all with an oblique incision. This was the only factor showing a statistical significant association with surgical site infection (P = 0.001). INTERPRETATION: The oblique incision is the only parameter with statistical significant association with infection after HTO. As this study type cannot prove causality, it is recommended to perform oblique incision only after careful evaluation of risks and benefits.

A new mechanical testing device for measuring anteroposterior knee laxity.

BACKGROUND: The authors assessed a new instrument, the Rolimeter, for the measurement of anteroposterior translation in the knee; it was compared to the KT-1000 arthrometer. PURPOSE: To determine if the Rolimeter offers a valid method for the measurement of anteroposterior translation that is as reproducible and reliable as the KT-1000 arthrometer. METHODS: Two of 3 observers examined 16 normal subjects (32 knees) and 36 patients (72 knees) with ligament ruptures twice, using both the Rolimeter and the KT-1000 arthrometers, 30 minutes apart. Total anteroposterior translation (manual maximal Lachman test) was recorded at 20 degrees and 80 degrees of knee flexion. RESULTS: On average, the Rolimeter measured approximately 1 mm less anteroposterior displacement than the KT-1000 arthrometer at manual maximum stress. Rolimeter measurements were more consistent than the KT-1000 measurements as measured by our observers. Specificity and sensitivity were equivalent between the Rolimeter and the KT-1000 arthrometer. CONCLUSIONS: The Rolimeter is as reproducible and reliable as the KT-1000 arthrometer. It offers a valid method for the measurement of anteroposterior translation in the knee. Higher accuracy was obtained at 20 degrees of flexion for the KT-1000 arthrometer and at 80 degrees of flexion for the Rolimeter.

Accuracy of frontal and sagittal plane correction in open-wedge high tibial osteotomy.

PURPOSE: This study was performed to determine the accuracy of correction in the frontal plane and to evaluate whether a frontal plane correction influences the sagittal slope of the proximal tibial surface in open-wedge high tibial osteotomy. TYPE OF STUDY: Retrospective review. METHODS: In this study, 30 patients (32 knees) with a mean age of 38 years (range, 20 to 66 years) were available for follow-up evaluation at a minimum interval of 24 months (mean, 42 months; range, 24 to 62 months). A normal axis was planned for a varus morphotype without evidence of osteoarthrosis. If one third of the thickness of the medial cartilage was lost, the new mechanical axis was planned to pass lateral to the center of the knee at the 10% position (where the 0% position is at the center of the knee joint and the 100% position is at the lateral border of the plateau). When two thirds were lost, the new mechanical axis was planned to pass through the 20% position. If total cartilage loss was present, the mechanical axis was planned to pass through the 30% position. The correction was estimated as good when the mechanical axis was found to be approximately +/- 5% of the width of the tibial plateau. The angle of the osteotomy and the size of the wedge-shaped bone graft were calculated using the "push" orthoradiogram. RESULTS: Consolidation of the osteotomy was obtained after a mean period of 8.4 weeks (range, 6 to 13 weeks). The mean amount of valgus correction was 5.9 degrees. Sixteen of 32 knees (50%) showed the desired position of the mechanical axis. Ten knees (31%) showed an undercorrection; 6 knees (19%) an overcorrection. The mean increase of the posterior tibial slope was 2.7 degrees (range, -8 degrees to 10 degrees ). CONCLUSIONS: The medial open-wedge osteotomy of the proximal tibia has a tendency to increase the posterior tibial slope. This effect is unfavorable in anterior knee instability because it increases the anterior translation of the tibia. Increasing the posterior slope can be favorable in posterior instability because it reduces the posterior sag. LEVEL OF EVIDENCE: Level IV.

Autologous osteochondral grafting in the knee: indication, results, and reflections.

The use of multiple autologous osteochondral plugs (mosaicplasty) for repair of articular cartilage defects is a well-accepted technique. Since 1995, the authors have used mosaicplasty to treat more than 110 patients with cartilage defects of the knee, hip, and ankle. The first 52 consecutive patients who had mosaicplasty of the knee and have an average followup of 37 months (range, 24-56 months) were examined. Indications for surgical treatment were osteochondritis dissecans, acute trauma, and posttraumatic lesions of the femorotibial joint, femoropatellar maltracking with recurrent episodes of patella dislocations, and distinct femoropatellar arthrosis. Preoperatively, cartilage defects were classified as International Cartilage Repair Society Grade III lesions in 23 patients and Grade IV lesions in 29 patients. Two years after surgery, an increased level of knee function was found in 86% of the patients. At the latest followup, improved knee function was observed in 92% of the patients. In four patients, reoperation was necessary because of graft failure. Complications and reoperation rate were related to large surface lesions. Autologous osteochondral transplantation is a valid option for the treatment of full-thickness osteochondral defects. However, the method is limited by the defect size and the number of plugs to be taken at the donor site.