Karl-Heinz Frosch

Outcomes and Risks of Operative Treatment of Rupture of the Anterior Cruciate Ligament in Children and Adolescents

PURPOSE The aim of this meta-analysis was to evaluate the clinical outcomes and risks of anterior cruciate ligament (ACL) surgery in children and adolescents. METHODS We electronically searched Medline, the Cochrane Controlled Trial Database, Embase, and Medpilot for studies on surgical treatment for ACL ruptures in skeletally immature patients. We extracted baseline demographics, follow-up intervals, surgical details (i.e., ligament suture or reconstruction, physeal-sparing or transphyseal techniques, type of transplant, and methods of fixation). Endpoints comprised rates of growth disturbances and reruptures, as well as knee function (measured by the International Knee Documentation Committees documentation system and the Lysholm score). Unweighted overall effect sizes (risks, risk ratios [RRs], and means of functional scores) were estimated by use of crude nominators and denominators, and random-effects meta-regression analysis was used for weighted data synthesis. RESULTS A total of 55 articles reporting on 935 patients (median age, 13 years; range, 1.5 to 16 years) were suitable for the study. After a median follow-up of 40 months (range, 14 to 89 months), the weighted rate of leg-length differences or axis deviations was 1.8% (95% confidence interval [CI], 0% to 3.9%] and that of reruptures was 4.8% (95% CI, 2.9% to 6.7%). Excellent or good function (International Knee Documentation Committee grade A or B) was achieved in 84.2% (95% CI, 75.8% to 92.6%) of all knees, and Lysholm scores averaged 96.3 (95% CI, 95.5 to 97.2). Transphyseal reconstruction was associated with a significantly lower risk of leg-length differences or axis deviations compared with physeal-sparing techniques (1.9% v 5.8%; RR, 0.34; 95% CI, 0.14 to 0.81) but had a higher risk of rerupture (4.2% v 1.4%; RR, 2.91; 95% CI, 0.70 to 12.12). Sutures did not result in any growth disturbances, with a weighted rerupture rate of 4.6% (95% CI, 2.6 to 6.7). Fixation far from the joint line fared better than close fixation with regard to this endpoint (1.4% v 3.2%; RR, 0.42; 95% CI, 0.09 to 1.93). Bone-patellar tendon-bone grafts, which are also less likely to fail, were associated with higher risks of leg-length differences or axis deviations than were hamstrings (3.6% v 2.0%; RR, 1.82; 95% CI, 0.66 to 5.03). Meta-regression did not show a significant impact of the publication year on event rates. CONCLUSIONS This meta-analysis showed low rates of leg-length differences or axis deviations and graft failures after ACL reconstruction in skeletally immature patients. Hamstring transplants may lower the risk of leg-length differences or axis deviations, and physeal-sparing techniques may increase the risk. Randomized controlled trials are needed to clarify important issues in managing ACL ruptures in children and adolescents. LEVEL OF EVIDENCE Level IV, meta-analysis of case series.

Influence of platelet-rich plasma on chondrogenic differentiation and proliferation of chondrocytes and mesenchymal stem cells.

Background/Aims: Autologous chondrocyte (CC) transplantation has the disadvantages of requiring two surgical interventions and in vitro expansion of cells, implying the risk of cellular dedifferentiation. Our clinical aim is to develop a one-step procedure for autologous CC transplantation, i.e. harvesting, isolation and reimplantation of CC performed in one single surgical procedure. Platelet-rich plasma (PRP) is a source of autologous growth factors reported to have mitogenic effects. The objective of this study was to test the influence of PRP as an autologous scaffold on freshly isolated CC and mesenchymal stem cells (MSC). Methods: CC and MSC were subjected to two- or three-dimensional (3D) growth systems, either with or without PRP. Chondrogenic differentiation was determined via quantification of collagen type II mRNA and immunohistochemical staining. Results: We observed a proliferative effect for MSCs exposed to PRP in monolayer culture and an increase in the expression of chondrogenic markers when cells are exposed to a 3D environment. CCs exposed to PRP show a decrease in the chondrogenic phenotype with increasing proliferative activity. Conclusion: PRP has a proliferative effect on CCs and MSCs. In a one-step procedure for autologous CC transplantation, this might be an advantage over other scaffold materials, but confirmation in in vivo studies is required.

Anatomy of Lateral Patellar Instability: Trochlear Dysplasia and Tibial Tubercle–Trochlear Groove Distance Is More Pronounced in Women Who Dislocate the Patella

Background A trend toward young women being at greatest risk for primary and recurrent dislocation of the patella is evident in the current literature. However, a causative factor is missing, and differences in the anatomical risk factors between men and women are less defined. Purpose To identify differences between the sexes in the anatomy of lateral patellar instability. Study Design Case control study; Level of evidence, 3. Methods Knee magnetic resonance images were collected from 100 patients treated for lateral patellar instability. Images were obtained from 157 patients without patellar instability who served as controls. Using 2-way analyses of variance, the influence of patellar dislocation, gender, and their interaction were analyzed with regard to sulcus angle, trochlear depth, trochlear asymmetry, patellar height, and the tibial tubercle—trochlear groove (TT-TG) distance. Mechanisms of injury of first-time dislocations were divided into high-risk, low-risk, and no-risk pivoting activities and direct hits. Results For all response variables, a significant effect was observed for the incidence of patellar dislocation (all P < .01). In addition, sulcus angle, trochlear asymmetry, and trochlear depth depended significantly on gender (all P < .01) but patellar height did not (P = .13). A significant interaction between patellar dislocation and gender was observed for the TT-TG distance (P = .02). The mean difference in TT-TG distance between study and control groups was 4.1 mm for women (P < .01) and 1.6 mm for men (P = .05). Low-risk and no-risk pivoting injuries were most common in women, whereas first-time dislocations in men occurred mostly during high-risk pivoting activities (P < .01). Conclusion The data from this study indicate that trochlear dysplasia and the TT-TG distance is more prominent in women who dislocate the patella. Both factors might contribute to an increased risk of lateral patellar instability in the female patient as illustrated by the fact that dislocations occurred most often during low-risk or no-risk pivoting activities in women.

Value of the tibial tuberosity-trochlear groove distance in patellar instability in the young athlete.

Background A lateralized tibial tubercle may be a relevant anatomic factor in patients with patellar instability and can be used as an indication for a distal realignment procedure. However, parameter values for the tibial tuberosity–trochlear groove (TT-TG) distance in the young patient have not been defined. It also remains to be determined how this parameter contributes to patellar instability in the growing knee joint. Purpose The purpose of this study was to evaluate the value of the TT-TG distance in patellar instability in the young athlete. Study Design Case control study; Level of evidence, 3. Methods Knee magnetic resonance images were collected from 109 patients with lateral patellar instability and from 136 control subjects. Student t test and multiple logistic regression analysis were used to compare the absolute and relative values of the TT-TG distance between patients and controls. The relative value was defined as the ratio between the TT-TG distance and the total width of the distal femur. Results The TT-TG distance (absolute and relative to femur width) differed significantly between patients with patellar dislocation and the control group (both P < .01). The TT-TG distances were on average 4 mm larger in patients with patellar dislocation; TT-TG distance divided by femur width was on average 5% larger in patients with patellar dislocation. Multiple logistic regression analysis confirmed the TT-TG distance as a significant risk factor for patellar dislocation (P = .04), but showed no significant interaction with patient age or femur width (P = .95 and P = .15, respectively). Conclusion A lateralized tibial tubercle is a relevant anatomic factor in the young athlete and in the adult patient with lateral patel-lar instability. Its parameter values and its influence on patellar dislocation are independent of patient age and should therefore be evaluated as in adults.

Magnetic resonance imaging characteristics of the medial patellofemoral ligament lesion in acute lateral patellar dislocations considering trochlear dysplasia, patella alta, and tibial tuberosity-trochlear groove distance.

PURPOSE The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability. METHODS Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity-trochlear groove (TT-TG) distance. RESULTS Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups. CONCLUSIONS The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint. LEVEL OF EVIDENCE Level IV, diagnostic case-control study.

A New Posterolateral Approach Without Fibula Osteotomy for the Treatment of Tibial Plateau Fractures

The selection of a surgical approach for the treatment of tibia plateau fractures is an important decision. Approximately 7% of all tibia plateau fractures affect the posterolateral corner. Displaced posterolateral tibia plateau fractures require anatomic articular reduction and buttress plate fixation on the posterior aspect. These aims are difficult to reach through a lateral or anterolateral approach. The standard posterolateral approach with fibula osteotomy and release of the posterolateral corner is a traumatic procedure, which includes the risk of fragment denudation. Isolated posterior approaches do not allow sufficient visual control of fracture reduction, especially if the fracture is complex. Therefore, the aim of this work was to present a surgical approach for posterolateral tibial plateau fractures that both protects the soft tissue and allows for good visual control of fracture reduction. The approach involves a lateral arthrotomy for visualizing the joint surface and a posterolateral approach for the fracture reduction and plate fixation, which are both achieved through one posterolateral skin incision. Using this approach, we achieved reduction of the articular surface and stable fixation in six of seven patients at the final follow-up visit. No complications and no loss of reduction were observed. Additionally, the new posterolateral approach permits direct visual exposure and facilitates the application of a buttress plate. Our approach does not require fibular osteotomy, and fragments of the posterolateral corner do not have to be detached from the soft tissue network.

Estrogen and raloxifene improve metaphyseal fracture healing in the early phase of osteoporosis. A new fracture-healing model at the tibia in rat

BackgroundFracture healing in osteoporosis is delayed. Quality and speed of fracture healing in osteoporotic fractures are crucial with regard to the outcome of patients. The question arises whether established antiosteoporotic drugs can further improve fracture healing.Materials and methodsOsteoporosis manifests predominantly in the metaphyseal bone. Nevertheless, an established metaphyseal fracture model is lacking. A standardized metaphyseal fracture-healing model with stable plate fixation was developed for rat tibiae. The healing process was analyzed by biomechanical, gene expression, and histomorphometric methods in ovariectomized (OVX) and sham-operated rats (SHAM), compared to standardized estrogen (E)- and raloxifene (R)-supplemented diets.ResultsEstrogen and raloxifene improved the biomechanical properties of bone healing compared to OVX (Yield load:

Metallic Biomaterials in Skeletal Repair

{\text{SHAM}} = 63.1 \pm 20.8{\text{N}}