Increased Posterior Condylar Offset Decreases the Extension Gap in Cases With Flexion Contracture in Modified Gap Technique Total Knee Arthroplasty.

Purpose There have been no reports comparing the change in medial and lateral posterior condylar offset (PCO) and the extension gaps. The purpose of this study was to elucidate the relationship between the change in medial and lateral PCO and the extension gap in total knee arthroplasty (TKA). The hypothesis is that an increase in both medial and lateral PCO can be a factor for a decrease in the extension gap, especially in cases of flexion contracture. Methods This retrospective study included 63 patients with medial osteoarthritis who underwent mobile-bearing PS-TKA using the modified gap techniques. Patients consisted of seven men (seven knees) and 53 women (56 knees), with the mean age of 76 (range, 58-88) years. The patients with valgus knee and cruciate retaining TKA were excluded. The medial ΔPCO (ΔPCO defined as the amount of change of the PCO before the resection of the posterior condyle and after the implant setting), lateral ΔPCO, the rotation angle of the posterior condyle osteotomy, and the gap differences were evaluated. The data were compared among three groups（Group A: ΔPCO increase on both sides, Group B: ΔPCO increase on only one side, Group C: ΔPCO decrease on both sides. The gap differences were compared between the cases with flexion contracture of ≥ 15° and the cases with flexion contracture of < 15°. The correlations between the gap differences and flexion contracture were evaluated in each group. Results There was no gap difference evident in any group (P≥0.05). The gap difference in Groups A (P=0.0067) and group C (P=0.0484) was significantly larger in cases with flexion contracture of ≥ 15° compared to those with flexion contracture of < 15°. Conclusions There was no correlation between the change in PCO and the extension gap. However, there was an inverse correlation between the flexion contracture and extension gap in cases with increased medial and lateral PCO.

Medial meniscus extrusion during gait is associated with decrease in knee rotation in early-stage knee osteoarthritis.

BACKGROUND: In patients with medial knee osteoarthritis (OA), medial meniscus extrusion during gait is aggravated by mechanical stress, such as knee adduction moment (KAM). Conversely, the decrease in the range of knee rotation during stance phase is also one of the important issues in early knee OA, whereas the correlation between medial meniscus extrusion and knee rotation during gait are unclear. RESEARCH QUESTION: To investigate the correlation between increase in medial meniscus extrusion and range of knee rotation during gait in patients with early- and late-stage of knee OA. METHODS: Forty patients with medial knee OA were enrolled and divided into early- and late-OA group by Kellgren-Lawrence grading scale. During gait tasks, the extent of medial meniscus extrusion was measured using ultrasonography and kinetic/kinematic data were measured using three-dimensional motion analysis system. The correlation between medial meniscus extrusion and the range of knee rotation or KAM were evaluated in the overall, early-, and late- OA groups. RESULTS: A significant negative correlation was observed between an increase in medial meniscus extrusion and range of knee rotation angle in early-OA group only. However, an increase in medial meniscus extrusion significantly correlated with the second KAM peak in the overall and early-OA groups. SIGNIFICANCE: The decrease in range of knee rotation during stance phase may be associated with the increase in medial meniscus extrusion during gait in patients with early knee OA.

Combined over-the-top reconstruction with posterolateral bundle remnant re-tensioning in pediatric anterior cruciate ligament reconstruction: A technical note.

Epiphyseal injury, particular on femoral side, is a major concern in pediatric anterior cruciate ligament (ACL) reconstruction. Therefore, the over-the-top route (OTTR) method has frequently been selected in pediatric ACL reconstruction, with good clinical results reported. However, a cadaver study reported the inferior rotational stability of the OTTR method to that of anatomical single bundle reconstruction. In recent years, a new method of reconstruction, which involves the remnant being detached, re-tensioned, and re-attached, achieved good short-term results. We developed a surgical method to restore the remnant to the posterolateral (PL) bundle footprint and obtain rotational stability in patients, thereby preserving the remnant. We hypothesized that repairing the residual remnant to the PL bundle footprint in pediatric ACL reconstruction could achieve rotational stability. This report offers the surgical techniques for PL bundle tensioning repair using remnants in the pediatric ACL OTTR procedure.

Effect of lateral wedge insole on medial meniscus extrusion and its association with knee osteoarthritis progression.

BACKGROUND: Medial meniscus extrusion (MME) is associated with knee osteoarthritis (OA) progression because of increased loading stress in the medial compartment of the knee. Using a lateral wedge insole (LWI) decreases loading stress and immediately reduces MME. OBJECTIVE: To investigate whether the wearing duration of LWI affects the midterm response to MME and is associated with knee OA progression. STUDY DESIGN: Cohort study. METHODS: Twenty-three patients with knee OA who were conservatively treated with LWI were classified according to the duration of the LWI wear per day: less than 5 h (short-duration group) or over 5 h (long-duration group). MME was evaluated in the single-leg standing position by ultrasound. Knee OA progression and limb alignment were evaluated radiographically. These evaluations were performed thrice: at the initial office visit as a baseline without LWI (time 0), with LWI (LWI-time 0), and 1 year after intervention with LWI (LWI-1 year). RESULTS: In both groups, the MMEs at LWI time 0 were significantly decreased compared with those at time 0. In the long-duration group, this reduction in MME was maintained 1 year after the intervention compared with time 0 (time 0: 3.9 ± 0.9, LWI-1 year: 2.6 ± 1.1), but this improvement was not observed in the short-duration group (time 0: 3.8 ± 1.7, LWI-1 year: 3.6 ± 1.7). In addition, three of four patients demonstrated OA progression, and varus alignment had significantly progressed compared with that at time 0 in the short-duration group. However, the long-duration group showed OA progression only in one patient and maintained limb alignment. CONCLUSIONS: The duration of wearing LWI affects the midterm reduction of MME and knee OA progression while maintaining limb alignment.

Needle Arthroscopy as a Promising Alternative to MRI for the Diagnosis of Meniscus Injury.

Meniscal injury is a common cause of knee pain and functional impairment, often necessitating surgical intervention. Although magnetic resonance imaging (MRI) is frequently used for diagnosis, its accuracy is variable and may lead to false positives and negatives. To address these issues, needle arthroscopy has gained attention as a potential diagnostic alternative to MRI because of its immediate availability and ability to directly visualize intra-articular structures. This study aimed to assess the diagnostic capabilities of needle arthroscopy in comparison with MRI and diagnostic arthroscopy for meniscal injuries. Forty patients with suspected meniscal injuries requiring surgical treatment were enrolled between November 2017 and March 2019. A needle arthroscope with a 0.95-mm diameter was used to evaluate meniscal injuries. Three orthopaedic surgeons with approximately 10 years of experience independently evaluated the images from the needle arthroscopy, diagnostic arthroscopy, and preoperative MRI without any knowledge regarding patients' information. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each modality were used to compare the diagnostic accuracies. For lateral meniscus (LM) injuries, the sensitivity, specificity, PPV, and NPV of needle arthroscopy compared to diagnostic arthroscopy were 0.706, 0.852, 0.148, and 0.294, respectively. For medial meniscus (MM) injuries, the corresponding values were 0.889, 0.864, 0.136, and 0.111, respectively. In comparison, MRI had a lower sensitivity for LM injuries (0.588) and a higher sensitivity for MM injuries (1.0). The agreement between diagnostic arthroscopy and needle arthroscopy was moderate (kappa=0.517), while the agreements between diagnostic arthroscopy or needle arthroscopy and MRI were poor. Similar patterns were observed for the presence, location, and tear patterns of meniscal injuries. In conclusion, needle arthroscopy shows promise as an effective diagnostic modality for meniscal injuries, surpassing the limitations of MRI.

Unique Anatomical Features of the Discoid Lateral Meniscus via Three-Dimensional MRI.

Background The discoid lateral meniscus (DLM) is a unique anatomical variant characterized by a larger, thicker lateral meniscus. For clinical diagnosis of DLM, coronal and sagittal slices in two-dimensional (2D) MRI and arthroscopic imaging are typically employed. However, evaluating the entire shape of the DLM is challenging due to the limited views and details provided by these methods. Three-dimensional (3D) visualization with MRI offers a more comprehensive view of the entire meniscus. The purpose of this study was to demonstrate the entire shape of a DLM using 3D images and unveil its unique characteristics. Methods The study population consisted of 31 knees diagnosed with DLM through arthroscopic examination at our hospital between 2017 and 2021. This group comprised 20 males (65%) and 11 females (35%), with ages ranging from 9 to 49 years (mean age, 24.2 years). Furthermore, a control group of 43 knees without DLM was included for comparative analysis. This control group consisted of 22 males (51%) and 21 females (49%), with ages ranging from 9 to 69 years (mean age, 28.5 years). 3D images of the medial meniscus (MM) and lateral meniscus (LM) were reconstructed from 1.5T-MRI images with semi-automatic segmentation using free software. From the coordinate information, the anterior-to-posterior lengths of the MM and LM were obtained, and the medial-to-lateral anterior-to-posterior length (L/M ratio) ratio was calculated and compared with the value of the non-DLM population. Results Our method allows for the detailed delineation of the DLM's unique morphology. The DLM group exhibited a significantly smaller L/M ratio compared to the non-DLM group (DLM: 0.66±0.06, non-DLM: 0.74±0.05, p<0.001). Conclusions Reconstructed 3D images could help to demonstrate the whole morphology of DLM and reveal its unique features, in which DLM shows a significantly smaller L/M ratio as compared to non-DLM.

Effect of limb alignment correction on medial meniscus extrusion under loading condition in high tibial osteotomy.

Background: This study aimed to investigate the effect of high tibial osteotomy (HTO) on medial meniscus extrusion (MME) and the association between the changes in limb alignment and MME under weight-bearing (WB) conditions after HTO. Methods: We included 17 patients with knee osteoarthritis (OA) who underwent HTO. MME was evaluated using ultrasonography in supine and unipedal standing positions. Knee alignment was evaluated radiographically using WB, whole-leg radiographs with the hip-knee-ankle angle (HKAA), percentage of the mechanical axis (%MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). All measurements were performed serially at four time points: preoperative and 3, 6, and 12 months postoperative. Clinical outcomes were assessed by knee injury and osteoarthrosis outcome score (KOOS) and visual analogue scale (VAS) value for pain. Results: Mean MME in the WB position was significantly greater than that in the supine position in the preoperative condition; however, MME in both supine and WB positions was significantly lowered postoperatively. The ΔMME, difference of MME between supine and WB positions, was significantly lowered postoperatively and maintained for up to 1 year. MME change in the WB position between preop and postoperative conditions was significantly correlated with change in HKAA and %MA at 1 year postoperative. KOOS and VAS score were significantly improved after HTO. Conclusions: HTO correcting varus alignment can decrease MME in WB position and minimise the change in MME between supine and WB positions. The changes in MME after HTO were correlated with changes in the mechanical alignments.

Toe-out gait inhibits medial meniscus extrusion associated with the second peak of knee adduction moment during gait in patients with knee osteoarthritis.

Background: A medial meniscus extrusion (MME) gradually expands during activities of daily living according to the mechanical stress on the medial compartment of the knee. Increase in MME occurs during the stance phase of the gait cycle, which is key for its expand. The knee adduction moment (KAM) represents the mechanical stress on the medial compartment; however, the relationship between the increase in MME and KAM is still unknown. Therefore, the present study aimed to investigate the relationship between MME during gait and KAM. Methods: Twenty-one patients with medial knee osteoarthritis and 11 healthy middle-aged adults were recruited. Three-dimensional motion analysis system and ultrasonography were used to measure the KAM and MME in the stance phase. The increase in MME was identified as the difference in MME between the maximum and minimum (ΔMME). Patients with knee osteoarthritis performed two conditions as normal and toe-out gait. The difference in KAM and ΔMME between conditions were evaluated. Results: ΔMME was correlated with the KAM second peak in normal gait of knee osteoarthritis patients (r = 0.51, p < 0.05). Toe-out gait reduced the KAM second peak and the ΔMME, and these reductions were correlated (r = 0.50, p < 0.05). Conclusions: Toe-out gait immediately inhibited the expansion of MME associated with the KAM second peak.

Unique patterns of medial meniscus extrusion during walking and its association with limb kinematics in patients with knee osteoarthritis.

Medial meniscus extrusion (MME) is exacerbated by repeated mechanical stress. Various factors would affect MME; however, there is limited information about the behaviour of the medial meniscus during walking in patients with knee osteoarthritis (KOA). This study aimed to investigate the pattern of MME during walking and its association with limb biomechanics in patients with KOA. Fifty-five patients with KOA and ten older adult volunteers as a control group were involved in this study. The MME and limb biomechanics during walking were evaluated simultaneously by ultrasound and a motion analysis system, respectively. The waveform was constructed from the values of MME, and the point showing the highest value of MME was identified during the gait cycle. According to the peak timing of MME in the waveform, the pattern of the waveform was evaluated and compared to the control group. Lateral thrust, knee adduction moment (KAM), and flexion moment were obtained from motion analysis, and their association with the MME was evaluated. The patients with KOA demonstrated unique peak timing during walking. Compared to the control group, there were three groups of MME waveforms, early (< 59%), normal (60-83%), and late (> 84%) from the peak timing in the gait cycle. The pattern of MME waveform in early, normal, and late groups was correlated with the first KAM and lateral thrust, second KAM, and knee flexion moment, respectively. A unique MME pattern during walking was demonstrated, and these patterns were associated with limb biomechanics in patients with KOA.

Visualization of lateral meniscus extrusion during gait using dynamic ultrasonographic evaluation.

PURPOSE: Medial meniscus extrusion is one of the risk factors for knee osteoarthritis (OA). However, lateral meniscus extrusion has not been discussed, and detailed information remains unknown. In particular, the lateral meniscus has high mobility and is expected to be difficult to evaluate in terms of its behavior under static conditions. Dynamic ultrasonographic evaluation was introduced to detect the dynamic behavior of the meniscus during walking. In this study, we aimed to investigate the behavior of the lateral meniscus during walking using dynamic ultrasonographic evaluation. METHODS: Sixteen participants with knee OA were recruited in this study. The change of lateral meniscus extrusion during walking was recorded using ultrasonography. Medial and lateral meniscal extrusion during the stance phase was measured, and meniscal mobility was defined as the difference in meniscal extrusion between minimum and maximum values (mm), medial meniscal extrusion (∆MME), and lateral meniscal extrusion (∆LME), respectively. The walking cycle and gait forms of lateral thrust were also evaluated using three-dimensional motion analysis systems and analyzed in terms of the correlation with ∆MME and ∆LME. RESULTS: The lateral meniscus was depicted in the articular plane, and extrusion decreased during the stance phase of the gait cycle. The ∆LME was significantly higher than the ∆MME (p < 0.01). There was a significant positive correlation between ∆LME and lateral thrust (r = 0.62, p < 0.05). CONCLUSIONS: We found that dynamic ultrasonographic evaluation can be used to visualize lateral meniscus extrusion during walking, and that its behavior is correlated to the degree of lateral thrust.

The effect of gait modification on the response of medial meniscus extrusion during gait in patients with knee osteoarthritis.

BACKGROUND: An increase in medial meniscus extrusion during weight-bearing conditions is associated with the progression of medial knee osteoarthritis (OA). Toe-out gait modification has been known to reduce the knee adduction moment (KAM); however, its effect on reducing the increase in medial meniscus extrusion in patients with knee OA remains unclear. RESEARCH QUESTION: To (1) evaluate the effect of toe-out gait on the increase in medial meniscus extrusion and the KAM in patients with medial knee OA and (2) investigate the synergetic effect of lateral wedge insoles in combination with toe-out gait in determining the most effective intervention for reducing medial meniscus extrusion during gait. METHODS: Twenty-five patients with medial knee OA were enrolled in this study. Participants walked under four conditions: normal gait, toe-out gait, normal gait with lateral wedge insoles, and toe-out gait with lateral wedge insoles. Medial meniscus extrusion and KAM peaks during gait were measured using ultrasound and a three-dimensional motion analysis system in each condition. These parameters were compared among the four conditions using repeated measures analysis of variance. RESULTS: The increase in medial meniscus extrusion and the second KAM peak were significantly lower in all interventions compared with those observed during normal gait. However, there was no significant difference among the interventions. SIGNIFICANCE: This study suggested that toe-out gait reduces the increase in medial meniscus extrusion and is associated with the reduction of the second KAM peak. However, no synergistic effect of lateral wedge insoles and toe-out gait was observed.

Comparison of clinical outcomes between anterior cruciate ligament reconstruction with over-the-top route procedure and anatomic single-bundle reconstruction in pediatric patients.

The purpose of this study is to evaluate the clinical results of over-the-top route (OTTR) reconstruction for pediatric anterior cruciate ligament (ACL) injuries and compare them with results of anatomic single-bundle reconstruction (SBR), which used the bone tunnel technique and was performed early after epiphyseal closure (age ≤15 years). This study included pediatric patients aged 11-15 years who underwent ACL reconstruction. The mean age at surgery was 13.4 years (11-15 years), including 14 men and 29 women. Operative procedures were determined according to growth plate closure. In all cases, the tibial side was reconstructed using a bone tunnel procedure. On the femoral side, we selected the OTTR procedure (group O) with open physis. Where the physis was closed, we selected the anatomical SBR (group B). The clinical results were evaluated with manual examination, the side-to-side difference (SSD) in tibial anterior translation using the Kneelax 3, and knee function score. There were no significant differences in the Lachman and pivot-shift tests, SSD in tibial anterior translation with Kneelax 3, or knee function score between the two groups before or after the surgery. Growth disturbance was not observed on either the femoral or tibial side in group O. The OTTR method provided comparable results with the bone tunnel anatomical method in manual examination, Kneelax 3, and knee clinical function scores, suggesting that the OTTR method is very useful for pediatric ACL reconstructions. Level of evidence: III; retrospective study.

Posterior wall blowout on computed tomography after anterior cruciate ligament reconstruction.

BACKGROUND: During anterior cruciate ligament (ACL) reconstruction, even when a posterior wall of the femoral bone tunnel is identified, computed tomography (CT) occasionally demonstrates a breach of the posterior femoral cortex of the femoral bone tunnel, i.e., posterior wall blowout, after ACL reconstruction (posterior wall blowout-like phenomenon). This study aimed to investigate the influence of the posterior wall blowout-like phenomenon on clinical outcomes after ACL reconstruction using hamstring tendon. METHODS: A total of 105 patients who underwent CT examination two weeks after ACL reconstruction were enrolled. A cortical suspension device was used for femoral side fixation in all cases. Posterior wall was identified in all cases during the surgery. The side-to-side difference in anterior knee laxity, pivot shift test, Lysholm knee score, the International Knee Documentation Committee (IKDC) subjective form, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were evaluated one year after the surgery. A second CT examination was performed 6-12 months after the surgery, if a posterior wall blowout-like phenomenon was identified in the first CT examination. RESULTS: Two weeks after the surgery, 16 of the 105 patients showed a posterior wall blowout-like phenomenon. Twelve of the 16 cases demonstrated a regenerated posterior femoral cortex of the femoral bone tunnel on their second CT images. There were no significant differences between the posterior wall blowout-like phenomenon group and the normal posterior wall group in terms of a side-to-side difference in anterior knee laxity (0.4 ± 1.5 mm and 0.1 ± 1.6 mm, respectively), pivot shift test, Lysholm knee score, IKDC score, and KOOS at one year after surgery. The length and diameter of the femoral bone tunnel were not significantly different between the two groups. CONCLUSIONS: Posterior wall blowout-like phenomenon after ACL reconstruction using a cortical suspension device did not negatively influence clinical outcomes. LEVEL OF EVIDENCE: III - retrospective comparative clinical study.

Comparison of the mechanical properties and mechanical damages to tendon tissue in three suspensory fixation techniques.

Background: Anterior cruciate ligament (ACL) injury is the most common traumatic injury to the knee joint. Suspensory fixation has become popular in ACL reconstruction because of its high primary stability, less invasiveness, and surgical convenience. There are two common types of suspensory fixation devices: those with fixed-length and those with adjustable-length loops. Owing to structural differences and differences in initial tensioning techniques, it is expected that mechanical property and damage to the tendons will vary from device to device; however, no literature has examined this so far. The main purpose of this study was to evaluate the damage caused to the tendon by three different suspensory fixation devices. An effective mechanical test was carried out as a prerequisite. Methods: First, the mechanical properties of simple loop device (SLD) as fixed-length loop device, first-generation, and second-generation adjustable devices (AD1 and AD2) as adjustable-length loop devices were tested (isolated device testing). Second, each device was tested using bovine extensor tendons (specimen testing). Cyclic testing included 2000 cycles; the devices were subsequently displaced until failure, and the ultimate tensile strength was determined using isolated device testing. Six samples of 3 devices were used in each testing experiment. After specimen testing, the surface structure of the tendon was evaluated quantitatively using optical coherence tomography (OCT) and our original histological scoring system. Results: During isolated device testing, SLD demonstrated the least cyclic displacement, followed by AD1 and AD2. The highest ultimate tensile strength was observed in AD2, followed by SLD and AD1. In specimen testing, the least cyclic displacement was observed in SLD, followed by AD1 and AD2. Histologically, AD1 demonstrated a significantly lower score, with damaged surface morphology, than SLD and AD2. OCT values were significantly higher, with a more disturbing tendon surface structure, in AD1 than in SLD and AD2. Conclusions: The first-generation adjustable loop device exhibited greatest graft tissue damage at the suspensory site in a clinically relevant setting. The thinner adjustable loop mechanism may have elevated graft damage by frictional stresses during loop adjustment or by repetitive tensioning stresses.

Equivalent outcomes of ACL revision with over-the-top single and double-bundle reconstruction using hamstring tendon compared to anatomical single and double-bundle reconstruction.

PURPOSE: In revision anterior cruciate ligament reconstruction (ACLR), our procedure of choice is the over-the-top route (OTTR) for cases where it is difficult to use a primary bone tunnel or to create a new bone tunnel due to the enlargement or malposition of the bone tunnel. Depending on the condition of the primary bone tunnel, we choose single (bone tunnel or OTTR) or double (bone tunnel or anteromedial (AM) bundle: OTTR /posterolateral (PL) bundle: bone tunnel) for femoral fixation. This study showed the results of single and double OTTR revision ACLR using the hamstring tendon. METHODS: Seventy-eight patients, who underwent revision ACLR using the hamstring tendon and who could be followed up for more than 2 year, were included in this study. The methods of revision ACLR were single in 54 cases (bone tunnel: 24 cases; OTTR method: 30 cases) and double in 24 cases (bone tunnel: 16 cases; OTTR for AM bundle and bone tunnel for PL bundle: eight cases). The cause of re-injury, the meniscus and cartilage injury, the reconstruction method, and the Lysholm score, Lachman test, Pivot-shift test, and the side-to-side difference in the tibial anterior translation were evaluated before and after surgery. RESULTS: There was no statistically significant difference in the Lyshom score, Lachman / Pivotshift test and side-to-side difference anterior translation of the tibia between the four groups. CONCLUSIONS: The clinical results of single and double OTTR revision ACLR are equivalent to those of anatomic single and double bone tunnel procedures.

Evaluation of the flexion gap with a distal femoral trial component in posterior-stabilized total knee arthroplasty.

PURPOSE: A distal femoral trial component was manufactured, and flexion gap size and inclination were evaluated with or without the distal femoral trial component in total knee arthroplasty (TKA). This study aimed to evaluate the effect of the distal femoral trial component on flexion gap size and joint inclination in posterior-stabilized (PS)-TKA. MATERIALS AND METHODS: A total of 84 patients with medial osteoarthritis who underwent mobile-bearing PS-TKA using modified gap techniques were included in this retrospective study. The flexion gap size and inclination before and after setting the distal femoral trial component were evaluated and compared with the final gap size and inclination. RESULTS: The joint gap size and inclination were significantly lower in those with than in those without the distal femoral trial component (P = 0.005, P < 0.001). The final gap size and inclination were similar to the gap size and inclination with the distal trial component (P = 0.468, P = 0.158). CONCLUSIONS: The joint gap size and medial tension in PS-TKA were significantly reduced after setting the distal femoral trial component. The flexion gap measured using the distal femoral trial component was similar to that when the final trial component was set. To more accurately perform the gap technique TKA, the flexion gap should be measured using the distal femoral trial component.

An older age, a longer duration between injury and surgery, and positive pivot shift test results increase the prevalence of articular cartilage injury during ACL reconstruction in all three compartments of the knee in patients with ACL injuries.

PURPOSE: To investigate factors that influence the prevalence of articular cartilage injury in patients with anterior cruciate ligament (ACL) injury. METHODS: This multicentre study included patients with ACL injury. Logistic regression analysis was conducted to identify factors that influence the prevalence of cartilage injury during ACL reconstruction. RESULTS: A total of 811 patients were enrolled. The factors that significantly influenced the prevalence of cartilage injury were age (odds ratio [OR], 1.04; P = 0.000), a positive pivot shift test result (OR, 1.43; P = 0.021), medial meniscal injury (OR, 2.55; P = 0.000), and delayed surgery (≥ 12 months) (OR, 2.52; P = 0.028) in the medial compartment of the knee; age (OR, 1.05; P = 0.000), subjective grades of apprehension during the pivot shift test (OR, 1.46; P = 0.010), lateral meniscal injury (OR, 1.98; P = 0.003), femoro-tibial angle (FTA) (OR, 0.92; P = 0.006), and delayed surgery (≥ 12 months) (OR, 2.63; P = 0.001) in the lateral compartment; and age (OR, 1.06; P = 0.000), body mass index (OR, 1.07; P = 0.028), a positive pivot shift test result (OR, 1.60; P = 0.018), FTA (OR, 0.90; P = 0.006), and delayed surgery (≥ 12 months) (OR, 3.17; P = 0.008) in the patellofemoral compartment. CONCLUSION: An older age, a longer duration between injury and surgery, and a positive pivot shift test result were positively associated with the prevalence of cartilage injury in three compartments in patients with ACL injuries. Early ACL reconstruction is recommended to prevent cartilage injury. LEVEL OF EVIDENCE: Level III.

Clinical outcomes of knee joint distraction combined with marrow stimulation procedures for patients with advanced knee osteoarthritis.

BACKGROUND: Knee joint distraction (KJD) has received much attention as a joint preserving surgery, especially in young patients with advanced knee osteoarthritis (OA). METHODS: This study included 16 patients with advanced knee OA who underwent KJD combined with marrow stimulating techniques and were followed up for more than 2 years. The patients' clinical scores, including the Japanese Orthopaedic Association (JOA) score, Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales, ROM, joint space width, and semiquantitative MRI were evaluated. The factors affecting clinical outcomes were analyzed. RESULTS: Postoperatively, the JOA score and the individual scores of the KOOS subscales improved significantly (JOA score: P = 0.0028, KOOS-symptoms: P = 0.0016, -pain: P = 0.0011, -ADL: P = 0.0009, -sports/recreation: P = 0.0144, and -QOL: P = 0.0034). Although the extension of the knee joint did not change throughout the follow-up period, flexion of the joint deteriorated at the time of device removal but recovered to the preoperative level at the final follow-up. Preoperative joint space width was 2.4 ± 2.0 mm and at the final follow-up, it increased to 3.3 ± 1.5 mm, showing statistically significant improvement (P = 0.034). The postoperative semiquantitative MRI score also improved significantly (from 6.0 ± 3.0 to 42.1 ± 28.7, P = 0.0001). A high BMI was associated with a poor clinical outcome. CONCLUSION: Although the effect of marrow stimulating techniques for cartilage repair was not well clarified and the complication rate was high, the clinical and radiographic outcomes showed significant improvement after KJD combined with marrow stimulating techniques in patients with advanced knee OA. However, we should be careful about suggesting this procedure in obese patients.

Application of a true lateral virtual radiograph from 3D-CT to identify the femoral reference point of the medial patellofemoral ligament.

PURPOSE: The purpose of this study is two-fold: (1) to describe the femoral reference point of the medial patellofemoral ligament (MPFL) on a virtual true lateral radiograph reconstructed from a three-dimensional computed tomography (3D-CT) image and (2) to compare this point with that of patients without patellofemoral instability and with Schöttle's point. METHODS: A total of 26 consecutive patients (29 affected knees) with recurrent patellar dislocation (RPD), who underwent MPFL reconstruction were included in this study (4 males; 22 females; mean age, 24.0 years old). Using a true lateral 3DCT image, the MPFL femoral insertion was identified and marked with a 2-mm circle, and this image was reconstructed as a virtual true lateral radiograph. Following Schöttle's method, the point of intersection was described by their anterior-posterior and proximal-distal positions. As a control population, 29 age- and gender-matched patients with anterior cruciate ligament (ACL) injuries were also analysed. RESULTS: The points in RPD patients were located significantly posterior (-2.5 ± 2.3 mm, p < 0.01) to the line representing an extension of the posterior cortex of the femur and distal (- 6.9 ± 2.4 mm, p < 0.01) to the posterior origin of the medial femoral condyle compared with those in the control population. The mean reference point of RPD patients was located in a 3.8-mm posterior and 4.4-mm distal position compared with Schöttle's point. CONCLUSIONS: An anatomical and radiographic femoral reference point of the MPFL on a true lateral virtual radiograph was described with our method. In patients with RPD, this reference point was identified to be more posterior and distal to Schöttle's point. More anatomical and individualized MPFL reconstruction will be secured using our method. LEVEL OF EVIDENCE: Level IV.