Comparison of Outcomes After Primary Versus Salvage Osteochondral Allograft Transplantation for Femoral Condyle Osteochondritis Dissecans Lesions.

Background: Osteochondral allograft transplantation (OCAT) allows the restoration of femoral condyle osteochondritis dissecans (OCD) lesions using an osteochondral unit. When OCD lesions are irreparable, or treatments have failed, OCAT is an appropriate approach for revision or salvage surgery. Based on its relative availability, cost-effectiveness, lack of donor site morbidity, and advances in preservation methods, OCAT is also an attractive option for primary surgical treatment for femoral condyle OCD. Hypothesis: OCAT for large femoral condyle OCD lesions would be highly successful (>90%) based on significant improvements in knee pain and function, with no significant differences between primary and salvage procedure outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: Patients were enrolled into a registry for assessing outcomes after OCAT. Those patients who underwent OCAT for femoral condyle OCD and had a minimum of 2-year follow-up were included. Reoperations, treatment failures, and patient-reported outcomes were compared between primary and salvage OCAT cohorts. Results: A total of 22 consecutive patients were included for analysis, with none lost to the 2-year follow-up (mean, 40.3 months; range, 24-82 months). OCD lesions of the medial femoral condyle (n = 17), lateral femoral condyle (n = 4), or both condyles (n = 1) were analyzed. The mean patient age was 25.3 years (range, 12-50 years), and the mean body mass index was 25.2 kg/m2 (range, 17-42 kg/m2). No statistically significant differences were observed between the primary (n = 11) and salvage (n = 11) OCAT cohorts in patient and surgical characteristics. Also, 91% of patients had successful outcomes at a mean of >3 years after OCAT with 1 revision in the primary OCAT cohort and 1 conversion to total knee arthroplasty in the salvage OCAT cohort. For both primary and salvage OCATs, patient-reported measures of pain and function significantly improved at the 1-year and final follow-up, and >90% of patients reported that they were satisfied and would choose OCAT again for treatment. Conclusion: Based on the low treatment failure rates in conjunction with statistically significant and clinically meaningful improvements in patient-reported outcomes, OCAT can be considered an appropriate option for both primary and salvage surgical treatment in patients with irreparable OCD lesions of the femoral condyles.

Morel-Lavallée lesion around the knee successfully treated with video-assisted endoscopic débridement: A case report.

We report a chronic Morel-Lavallée lesion around the knee in a competitive high schooler softball player, successfully treated with video-assisted endoscopic debridement. Endoscopic surgery is a viable option to treat Morel-Lavallée lesions in active patients who seek a rapid return to sport. The potential advantages of an endoscopic treatment would be a faster healing process and an earlier return to motion and function due to a less morbid and more cosmetic surgical approach.

Biomechanics of internal fixation in Hoffa fractures - A comparison of four different constructs.

OBJECTIVE: Compare the biomechanical effectiveness of four different bone-implant constructs in preventing fracture displacement under axial loading. METHODS: Twenty artificial femora had a standardized coronally oriented fracture of the lateral femoral condyle, representing a Hoffa fracture classified as a Letenneur type I. Four different fixation constructs were applied to the synthetic bones for biomechanical testing. The constructs consisted of a posterolateral (PL) buttressing locking plate in conjunction with two cannulated lag screws inserted from posterior to anterior (PA) - Group 1; Two cannulated screws inserted from anterior to posterior (AP) without plating- Group 2; A posterolateral (PL) buttressing locking plate in isolation - Group 3; and a combination of two lag screws from anterior to posterior (AP) in addition to a horizontal one-third tubular locking plate - Group 4. An axial load was applied to the fracture site with a constant displacement speed of 20 mm/min, and the test was interrupted when a secondary displacement was detected determining a fixation failure. We recorded the maximum applied force and the maximum fracture displacement values. RESULTS: Group 1 demonstrated the highest overall bone-implant axial stiffness with the lowest secondary displacement under loading. Groups 3 and 4 showed equivalent mechanical behavior. Group 2 presented the lowest mechanical stiffness to axial loading. The combination of the one-third tubular locking plate with anterior-to-posterior lag screws (Group 4) resulted in 302 % increase in fixation stiffness when compared to anterior-to-posterior lag screws only (Group 2). CONCLUSIONS: This study confirms the mechanical superiority of having a plate applied parallel to the main fracture plane in the setting of coronally oriented femoral condyle fractures. The addition of a horizontal plate, perpendicular to the main fracture plane, significantly increased the resistance to shearing forces at the fracture site when compared to constructs adopting just cannulated screws. LEVEL OF EVIDENCE: Biomechanical study.

Treatment failures (revision or arthroplasty) after knee osteochondral allograft transplantation with minimum two-year follow-up.

BACKGROUND: Knee osteochondral allograft transplantation (OCAT) has been associated with good short- to mid-term outcomes, however, treatment failures occur more frequently than desired. This study used data from a lifelong outcomes registry to analyze knee OCAT treatment failure rates, variables associated with knee OCAT treatment failures, and outcomes after revision or arthroplasty surgery for knee OCAT treatment failures. METHODS: Patient outcomes were followed after knee OCAT performed using standard preservation (SP) or Missouri Osteochondral Preservation System (MOPS®) allografts. The study population consisted of patients undergoing primary OCAT with ≥ 2-year follow-up. For comparisons, the treatment failure population was defined by patients in the study population with documented treatment failure (revision or arthroplasty) with ≥ 2-year follow-up after failure. Functional graft survival was defined as no further need for revision surgery after primary or revision OCAT. RESULTS: A total of 262 patients (n = 136 males; 51.9%) were analyzed. SP grafts were used for 59 cases and MOPS grafts were used for 203 cases. Treatment failure was documented in 61 cases (23.3%). MOPS grafts were 3.3 times more likely to be associated with functional graft survival. SP grafts, older patient age, higher BMI, tibiofemoral bipolar OCAT and non-adherence to the postoperative rehabilitation protocol were significantly associated with treatment failure. CONCLUSIONS: Knee OCAT resulted in functional graft survival at short- to mid-term follow-up in the majority (70-88%) of cases. In addition, revision of primary OCAT resulted in functional graft survival for at least 2 years after revision surgery in the majority (66%) of patients. LEVEL OF EVIDENCE: 2, prospective cohort study.

Onlay Technique for Posterior Cruciate Ligament Reconstruction: The Paccola's Technique.

The primary function of the posterior cruciate ligament (PCL) is to restrict the posterior translation of the tibia, and its secondary function is to limit the tibial external rotation, mainly at 90° and 120° of knee flexion. The prevalence of PCL rupture ranges between 3% and 37% of patients with knee ligament tears. This ligament injury often is associated with other ligament injuries. Surgical treatment is recommended for acute PCL injuries associated with knee dislocations or when stress radiographs show a tibial posteriorization greater than or equal to 12 mm. The techniques classically described for the surgical treatment are inlay and transtibial, which can be performed in a single- or double-bundle fashion. Biomechanical studies suggest that the double-bundle technique is superior to the single femoral bundle, suggesting less postoperative laxity. However, such superiority has not yet been proven in clinical studies. This paper will describe the step-by-step technique for PCL surgical reconstruction. The tibial fixation of the PCL graft is performed by using a screw and spiked-washer, and the femoral fixation can be done with a single- or double-bundle technique. We will explain the surgical steps in detail, with tips to perform them simply and safely.

Determination of Standard Values for Knee Version in a Healthy Population.

BACKGROUND: Different measures are used to describe relevant anatomic variations that can result in patellofemoral instability and disorders. Knee version, the relative rotational alignment between the femur and tibia in the axial plane at the level of the knee, may have a decisive effect on the kinematics of the patellofemoral joint. However, data regarding the values of knee version are currently lacking. PURPOSE: This study aimed to determine standard values for knee version in a healthy population. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 100 healthy volunteers (50 male and 50 female) without patellofemoral disorders or lower extremity malalignment were included in this study and underwent knee magnetic resonance imaging. The torsion values of the femur and tibia were independently measured using the Waidelich and Strecker method. Knee version, defined as static rotation of the tibia with respect to the femur in full extension, was determined by measuring the angle between the tangent lines to the dorsal femoral condyle (DFC) and the dorsal tibial head (DTH; defined by the posterior point of the proximal tibial plateau). Supplementary measurements were obtained as follows: (1) femoral epicondylar line (FEL), (2) tibial ellipse center line (TECL), (3) tibial tuberosity-trochlear groove (TT-TG) distance, and (4) tibial tuberosity-posterior cruciate ligament (TT-PCL) distance. RESULTS: In 200 analyzed legs of 100 volunteers (mean age, 26.5 ± 5.8 years [range, 18 to 40 years]), we identified a mean internal femoral torsion of -23.8°± 9.7° (range, -46.2° to 1.6°), external tibial torsion of 33.2°± 7.4° (range, 16.4° to 50.3°), and external knee version (DFC to DTH) of 1.3°± 3.9° (range, -8.7° to 11.7°). Other measurements were as follows: FEL to TECL, -0.9°± 4.9° (range, -16.8° to 12.1°); FEL to DTH, -3.6°± 4.0° (range, -12.6° to 6.8°); and DFC to TECL, 4.0°± 4.9° (range, -12.7° to 14.7°). The mean TT-TG distance was 13.4 ± 3.7 mm (range, 5.3-23.5 mm), and the mean TT-PCL distance was 11.5 ± 3.5 mm (range, 6.0-20.9 mm). Female participants had significantly greater external knee version than male participants. CONCLUSION: Coronal- and sagittal-plane alignments of the knee have a well-known effect on the biomechanics of this joint. Additional information about the axial plane may result in new decision-making algorithms for managing knee disorders. This study is the first to report standard values of knee version in a healthy population. As a subsequent step building on this work, we advocate for the measurement of knee version in patients with patellofemoral disorders, as this parameter may assist with new treatment guidelines in the future.

Risk of shortening in operatively treated proximal femur fractures with cephalomedullary nails with dynamically versus statistically locked helical blades.

INTRODUCTION: Cephalomedullary nails (CMN) have proven to be effective for the fixation of unstable pertrochanteric hip fractures, but limited data exists regarding the degree of shortening that occurs with nailing systems that offer "dynamically" versus "statistically" locked helical blades. This study aimed to determine the incidence, timing, and amount of postoperative fracture shortening in patients with pertrochanteric hip fractures treated with "dynamically" versus "statistically" locked helical blades. METHODS: A retrospective review was performed on patients requiring operative fixation of pertrochanteric fractures. Inclusion criteria were patients aged 55 or older, low energy mechanism of injury, primary surgical open reduction and internal fixation of the injury, surgery performed by a fellowship-trained orthopaedic traumatologist, and radiographic follow up until healing or failure (minimum of 3 months). Quantification of fracture shortening was determined using the lateral screw protuberance method. Fracture shortening measurements were calculated from immediate post-operative films and subsequent radiographs at each follow-up visit. RESULTS: 222 patients met inclusion criteria (123 using Depuy Synthes Trochanteric Fixation Nail proximal femoral nailing system (TFN) with static locking; 65 TFN with dynamic locking; 23 using Depuy Synthes Trochanteric Fixation Nail-Advanced proximal nailing system (TFNA) with static locking; and 11 TFNA with dynamic locking). When comparing the final screw protuberance, the TFN dynamic (10.31 mm), TFNA static (9.52 mm), and TFNA dynamic (7.02 mm) groups were found to be significantly less compared to the TFN static cohort (11.67 mm; p < 0.001). The distribution of fracture shortening was found to be significant (p < 0.01). Interval measurements of fracture shortening by repeated measures of ANOVA within groups showed statistically significant increases in screw protuberance for the TFN static (p < 0.001), TFN dynamic (p < 0.001), and TFNA static (p < 0.01) cohorts within the first 60 days postoperatively. The TFNA with dynamic locking group was found to have statistically significant increases until the first 100 days post-operatively (p < 0.02). DISCUSSION: The incidence of fracture shortening remains high even with the use of cephalomedullary nails, regardless of dynamization status. Current pertrochanteric fixation constructs continue to favor fracture healing at the direct expense of fracture shortening.

Online Instruction to Measure Axial Alignment with the Bonesetter App.

Background and objectives: Alignment of the lower extremity is important when treating congenital deformities, fractures, and joint replacement. During the COVID-19 pandemic, AO North America offered an online course on deformity measurement and planning. The Bonesetter app is a deformity planning tool that is freely available online. The purpose of this study was to see how effective an online course was in teaching axial alignment measurement and to assess that skill using an online digital planning tool, the Bonesetter app. Materials and Methods: An online module on axial alignment was provided during the AONA osteotomy course as well as a tutorial on how to use an online digital planning tool (Bonesetter app). The tools within the Bonesetter app allow users to draw digital lines directly on the CT images and measure the exact angle between two planes. Participants in this study were directed to perform these measurements in four different cases that tested different variations of deformity. Results: The measurements were completed correctly in case 1 = 56%, case 2 = 61%, case 3 = 84%, and case 4 = 76%. The standard deviation of angular digital measurements between individuals was ±4.26 degrees. Measuring the angle directly vs. drawing angles to a horizontal line had smaller standard deviations per case (p < 0.005) and less incidents outside 1 standard deviation for each measurement. Errors in adding and subtracting were the most common errors, particularly in relation to femoral anteversion or retroversion. Conclusions: The online course successfully instructed a group of orthopedic surgeons to measure alignment and malalignment of lower limb axial deformities. The Bonesetter app helped participants to learn this skill and identify errors in measurement. The inability to differentiate between anteversion and retroversion of the femur is a common source of error when it occurs and should be a focus of instruction.

Preoperative Planning and Preservation of the Knee with Complex Osteotomies.

The knee is a complex structure composed of bone, cartilage, menisci, ligaments and muscles, which all work synergistically to optimize congruence, stability, and function. Osteotomies are procedures addressing an abnormal joint alignment, shifting the mechanical load from a diseased joint compartment to a healthier one. Preoperative planning is an important art of identifying the source of abnormal load distribution to the joint, enabling the surgeon to simulate a deformity correction ahead of the surgical procedure.

Revisiting the management of tibial plateau fractures.

Three-dimensional imaging has changed the understanding and management of tibial plateau fractures. In the 1970s, Schatzker proposed a classification for tibial plateau fractures, which highlighted the morphology of the six principal types. More recently, this original classification was complimented by an extended one underscoring the importance of understanding where the split wedge fragment(s) is/are located in three dimensions. The extended classification introduced the split wedge fragment and the continuity of the rim as the determinants of joint stability and the critical role that this plays in the management of tibial plateau fractures. The current manuscript re-emphasizes contemporary concepts of tibial plateau stability and depicts key issues which must be considered when planning the definitive surgical fixation of tibial plateau fractures.

The Value of a Standardized Knee Functional Assessment in Predicting the Outcomes of Total Knee Arthroplasty.

Questionnaires and physical tests are tools to determine the ability of an individual to perform tasks of the daily living. In our institution, a standardized knee performance evaluation including patient-reported outcome measures (PROMs) and physical performance tests has been applied to all patients undergoing total knee arthroplasty (TKA). Our goal was to identify which preoperative tools influence the outcomes of a TKA and if physical performance tests can be of value if used along with PROMs in predicting functional outcomes. Classification and regression tree was used to analyze which preoperative factors influence function after TKA. Western Ontario and McMaster Universities Arthritis Index (WOMAC) function (WOMAC-F), 6-minute walk test (6MWT), and timed up and go (TUG) test at the 12th postoperative month were the dependent variables. Age, body mass index, preoperative WOMAC function and pain score, muscle strength, 6MWT, and TUG test score were used as preoperative predictors of dependent variables. TUG ≤19.3 seconds and age <62 years were preoperative predictors of better scores in the WOMAC-F (5.5). Strength of extensor muscles of the nonoperated knee ≥99.43 N·m/kg and 6MWT> 328 m were preoperative predictors of a better postoperative 6MWT (499 m). TUG <12.3 seconds and 6MWT ≥421 m were preoperative predictors of better postoperative TUG (7.3 seconds). Preoperative performance in physical tests had an influence on postoperative outcome scores than PROMs after TKA. Less age, good muscular strength, greater capacity of walking, and smaller TUG times were associated with better outcomes.

Comminuted patellar fractures: The role of biplanar fixed angle plate constructs.

BACKGROUND: Comminuted patellar fractures represent a challenging clinical problem. Treatment aims to restore the integrity of the extensor mechanism and the congruity of patellofemoral joint. Controversy exists regarding the ideal fixation method. Metallic constructs aiming to convert pulling forces on the anterior aspect of the patella into compression forces across the fracture site are the standard of care. More recently, low profile plates have been described in the management of comminuted patellar fractures. The aims of this study were to (1) develop a novel unstable patellar fracture model and (2) to compare biomechanically three different constructs for fixation comminuted patellar fractures. We hypothesized that an orthogonal biplanar disposition of the screws within an anteriorly placed locking plate provides the best biomechanical properties in the management of comminuted fractures. METHODS: Six-part complex AO 34-C3 patella fractures were simulated in 18 human cadaveric knees by means of osteotomies including comminution around the distal patellar pole. The specimens were randomly assigned to 3 fixation techniques (n â€‹= â€‹6) for either anterior plating, antero-lateral plating, or tension band wiring (TBW). Biomechanical testing was performed over 5000 cycles in active extension and passive flexion, followed by ultimate destructive quasi-static testing. Interfragmentary movements were captured by means of optical motion tracking. RESULTS: Displacement between the proximal and distal medial patella fragments was lower after anterior plating compared to both antero-lateral plating (P â€‹= â€‹0.084) and TBW (P â€‹< â€‹0.001). Moreover, displacement between the proximal and distal lateral fragments was significantly lower after anterior plating compared to both other techniques (P â€‹≤ â€‹0.032). In addition, it was significantly lower for antero-lateral plating versus TBW (P â€‹< â€‹0.001). Rotation around the medio-lateral axis between the proximal and distal medial fragments was significantly lower after anterior plating compared to TBW (P â€‹= â€‹0.017). CONCLUSIONS: Anterior mesh plating with biplanar placement of locking screws provides superior stability for fixation of comminuted patellar fractures when compared to both antero-lateral mesh plating and TBW. The latter is associated with considerably inferior performance.

Expanding the horizons of clinical applications of proximal humerus locking plates in the lower extremities: A technical note.

Pre-contoured anatomical locking plates were designed to address the clinical need of fixing small epiphyseal segments with a larger number of screws. Those plates match the contour and shape of a variety of bones allowing for optimal buttress properties. The aim of this manuscript is to highlight the benefits of applying proximal humerus locking plates in the fixation of lower extremity bones. Although designed for the proximal humerus, the low-profile plate shape and anatomic contour also provides versatile use in certain areas of the lower extremity. This technical narrative highlights the versatile and reliable use of this plate for other anatomical areas than the one to which it has been originally conceived.

Non-locked and locked small fragment straight plates have a similar behavior in buttressing the posteromedial shear tibial plateau fragment: a biomechanical analysis of three different fixations.

PURPOSE: The aim of this study is to compare the biomechanical behavior of three different fixation constructions currently used for buttressing the posteromedial shearing tibial plateau fragment. Our hypothesis is that non-locked implants provide sufficient comparable stability in posteromedial tibial plateau fractures as locked implants. METHODS: Fifteen left synthetic tibiae from a single manufacturing batch were used to create a posteromedial shear tibial plateau fracture. The fracture was buttressed with three different posteriorly placed five-hole straight small-fragment plate. Five models were fixed with a one-third tubular plate (TTP), five models with a dynamic compression plate (DCP), and five models with a locking compression plate (LCP). All groups were tested to vertical subsidence (Stage 1). In the same experiment (Stage 2), TTP and DCP groups were tested until catastrophic failure. Force versus displacement curves were obtained in the two stages of the experiment. RESULTS: Stage 1 - There was no significant difference in stiffness (p = 0.89), subsidence up to 2 mm (p = 0.38), and energy (p = 0.36) among the three fixation constructions. Stage 2 - Yield load revealed significantly less yield strength for the TTP group as compared with the DCP group (p = 0.048). However, there was no significant difference in maximum load to failure among the TTP and DCP fixation constructions (p = 0.16). CONCLUSION: Placement of either a locked or non-locked small fragment straight plate to buttress the posteromedial shear tibial plateau fragment has a similar biomechanical behavior. When the implant is positioned to buttress the shearing fragment it maximizes biomechanical stiffness.

Induced-Membrane Technique in the Management of Posttraumatic Bone Defects.

BACKGROUND: Critical-size bone defects are defined as bone defects where spontaneous regeneration is not expected without treatment1. The characteristics of bone defects (etiology, location, size, presence of infection, and soft-tissue conditions) vary greatly and, to be effective, the treatment method should address this variability. The induced-membrane technique, or Masquelet technique, is a method for treating critical-size bone defects2,3 of various sizes and anatomic locations. It has been used to treat infected and noninfected bone defects and may be performed with a variety of fixation methods2,3. DESCRIPTION: The induced-membrane technique is a 2-stage procedure. The first stage consists of debridement followed by insertion of a polymethylmethacrylate (PMMA) spacer in the bone defect. The presence of the PMMA leads to a foreign-body reaction with the development of a thick pseudosynovial membrane that is extremely vascularized and rich in growth factors. The filling of the bone defect with the cement spacer prevents fibrous tissue invasion and allows the development of an optimal vascularized gap for bone-grafting. After 6 to 8 weeks, the membrane around the spacer is carefully opened for the removal of the spacer, which is then replaced by bone graft2,3, which can be expanded with allograft or biomaterials. ALTERNATIVES: Alternatives include vascularized or nonvascularized autologous bone graft, allograft, bone transport methods, titanium cages, megaprostheses, shortening, and amputation. RATIONALE: Posttraumatic bone defects frequently are associated with soft-tissue injury and infection that impair the local vascularization and the healing potential. The highly vascularized induced membrane may play a role in restoring the local regenerative capacity. Numerous studies have demonstrated its successful use in the treatment of posttraumatic bone defects in the hand, forearm, humerus, femur, tibia, and foot. The induced-membrane technique is especially advantageous in the treatment of infected bone defects because the presence of the spacer helps in the treatment of the infection by reducing dead space, acting as a local antibiotic carrier, and promoting some degree of bone stability3-5.

Setting Yourself Up for Success: Locked Plating in Periprosthetic Fractures About Total Knee Arthroplasty.

As the incidence of total knee arthroplasty increases, a concurrent increase in periprosthetic fractures will also occur. This article focuses on the most common fracture types and current strategies adopted to overcome this challenging clinical problem. Our goal is to outline the role of locking plates in the management of knee periprosthetic fractures.

Nutrition and Inflammation Influence 1-Year Mortality of Surgically Treated Elderly Intertrochanteric Fractures: A Prospective International Multicenter Case Series.

INTRODUCTION: Hip fracture is a common and devastating event in older adults causing increased dependence, comorbidity, and mortality. Since new surgical techniques have not significantly improved the mortality rate, a better understanding of patient risk factors could improve the treatment algorithm and outcomes. This prospective study aimed to document the 1-year survival rate of patients with intertrochanteric fracture treated surgically in Latin America and to investigate risk factors associated with 1-year mortality. PATIENTS AND METHODS: Between January 2013 and March 2015, 199 patients were prospectively enrolled. Inclusion criteria were aged 60 years or older, isolated intertrochanteric fracture (AO/OTA 31-A), and time to surgery within 10 days after injury. The follow-up period was 1 year. The association between mortality and patient demographics, comorbidity, surgical details, and preoperative laboratory parameters was assessed using log-rank tests. RESULTS: Twenty patients died by 365 days after surgery (including 5 that died within 30 days of surgery) resulting in a 1-year survival rate of 89.8% (95% confidence interval = 84.6-93.3). The 1-year mortality was significantly associated with age (≥85 years old, P = .032), existing comorbidity (P = .002), preinjury mobility level (P = .026), mental state (Mini-Mental State Examination > 23, P = .040), low preoperative plasma albumin level (P = .007), and high preoperative blood C-reactive protein level (CRP; P = .012). At the 1-year follow-up, patients on average did not regain their preinjury hip function and mobility, although the self-assessed quality of life was equal or better than before the injury. DISCUSSION: As a prospective study, the current patient population had clear inclusion and exclusion criteria and was relatively homogeneous. The resulting associations between 1-year postoperative mortality and preoperative hypoalbuminemia and preoperative elevated CRP level are therefore especially notable. Previously identified risk factors such as male gender and time to surgery showed no significant association with 1-year mortality-the overall favorable condition of the current population or the lack of statistical power maybe responsible for this observation. CONCLUSION: The current results showed that under the condition of optimal surgical treatment and low surgery-related complication, preinjury health status as indicated by the blood level of albumin and CRP has a direct and significant impact on 1-year mortality rate.

Onlay Reconstruction of the Posterior Cruciate Ligament: Biomechanical Comparison of Unicortical and Bicortical Tibial Fixation.

Posterior cruciate ligament (PCL) injuries are generally associated with high-energy trauma. There are many controversies regarding optimal surgical technique in regard to graft selection and fixation methods. The recently described onlay technique allows for direct fixation of a hamstring autograft to the posterior aspect of the tibia with cancellous screw and spiked washer, while protecting the neurovascular structures and avoiding the so-called "killer turn." The objective of this study was to compare immediate postimplantation biomechanics of unicortical versus bicortical tibial fixation of onlay PCL grafts. Eight knees were randomly assigned to one of two onlay PCL techniques (n = 4 knees/technique), performed by a single experienced surgeon. Testing consisted of a posterior-directed force at four knee flexion angles, 10, 30, 60, and 90 degrees, to measure load to 5 mm of posterior displacement, maximum displacement (at 100 N load), and stiffness. For statistical analyses, data for each knee were normalized to the native PCL-intact knee and were then grouped into unicortical or bicortical groups accordingly. Data for load to 5 mm (strength), displacement at 100 N, and stiffness were compared among PCL-intact, PCL-deficient, unicortical fixation, and bicortical fixation categories using one-way analysis of variance to assess for statistically significant (p < 0.05) differences. When compared with PCL-deficient knees, both fixation techniques had less laxity. When compared with PCL-intact knees, unicortical had more laxity at all angles, and bicortical had more laxity only at 90 degrees (p < 0.001). For relative graft strength, intact knees required significantly higher loads than both treatment groups. Bicortical, however, outperformed unicortical at all angles (p < 0.001) for relative strength. Regarding stiffness, there were no significant differences between unicortical and bicortical, and both were superior to PCL-deficient and inferior to PCL-intact knees. Based on cadaveric biomechanical testing, none of the reconstructed PCL knees was able to replicate the intact native PCL, but both techniques were superior to PCL-deficient knees. The bicortical tibial fixation technique appears to have biomechanical advantages when opting for onlay PCL reconstruction.