The main function of anterior cruciate ligament (ACL) is to maintain stability of the knee joint and prevent anterior displacement of the tibial plateau. ACL injury accounts for more than 50% of the knee joint injuries. If not timely handled, it will increase the risk of secondary injuries to structures such as the meniscus and cartilage, causing chronic pain and degeneration of the knee joint. Although most ACL injuries can be determined by their direct signs on MRI, the identification of complex situations and partial tears of ACL are still not satisfactory, which subsequently affects treatment strategies. After ACL injury, changes in anatomical relationship of the knee joint can also lead to morphological changes in other structures such as the posterior cruciate ligament (PCL) on MRI, and these indirect signs can assist in the diagnosis of ACL injury. The authors reviewed the application of MRI-related indicators of PCL in diagnosing ACL injury, hoping to provide references and new ideas for clinical decision-making.

A 53-year woman and her 18-year daughter presenting with bone pain, bone fractures, bone deformities and short stature were admitted to Gansu Provincial People′s Hospital in March 2021. Laboratory tests showed low blood phosphorus, low renal phosphorus threshold, normal or low blood calcium, and normal or increased PTH. The high-throughput sequencing indicated heterozygous mutations of the PHEX gene (Phosphate-regulating gene with Homology to Endopeptidases on the X chromosome) in two patients, which was not detected in other family members; finally the diagnosis of X-linked dominant hypophosphatemic rickets/osteomalacia(XLH)was confirmed for these two patients. Treated with neutral phosphorus solution and Rocaltrol, bone pain was relieved completely in the younger patient, but not for her mother due to long disease course and severe complications. Because of the large heterogeneity of the disease there are high missed diagnosis and misdiagnosis rates for XLH. In this paper a pedigree of XLH is reported with literature review.

Objective:To measure the anatomical parameters of the simulated low tibial tunnel of posterior cruciate ligament (PCL) based on knee CT images so as to provide clinical reference for accurate location of the tunnel.Methods:The CT images of 201 healthy knee joints collected at Department of Orthopedics, The Second Hospital of Lanzhou University from June 2016 to September 2021 were used for simulation of the PCL low tibial tunnel. The anatomical parameters of the tibial tunnel were measured using the RadiAnt DICOM Viewer. The primary measures included the angle between tibial plateau and tibial tunnel (ATPT) and the perpendicular distances from the tibial tunnel entrance and exit point to the tibial plateau (L1 and L2). The secondary measures included the angle between tibial plateau and posterior slope (PSA), the angle between tibial anatomical axis and central line of tibial tunnel (ATAA), the angle between posterior tibial slope line and the central line of tibial tunnel (APST), the anterior and posterior diameter of tibial plateau (APD), the length of posterior tibial slope (LPTS), and the length of tibial tunnel (LTT). The measurement results were analyzed according to the body height (divided into 3 groups: a 1.00 to 1.60 m group, a 1.61 to 1.70 m group, and a ≥1.71 m group) and gender using the software IBM SPSS 26.Results:The primary measures: ATPT was 37.0°±4.5°, and L1 and L2 were respectively (57.8±7.4) mm and (34.5±3.3) mm. The secondary measures: PSA 128.1°±5.4°, ATAA 52.7°±4.1°, APST 89.1°±5.9°, APD was (32.9±2.6) mm, LPTS (20.5±2.4) mm, and LTT (40.9±5.7) mm. After grouping by gender, there was no significant difference in PSA between men and women ( P>0.05) while there were significant differences in the other indexes between men and women ( P<0.05). After grouping by body height, there was no significant difference in ATPT, PSA, APST or ATAA between the 3 groups (1.00 to 1.60 m group, 1.61 to 1.70 m group and ≥1.71 m group) ( P>0.05) while there were significant differences in L1, L2, APD, LPTS and LTT between the 3 groups ( P<0.05). Conclusions:Based on the knee CT images, the primary measures of PCL low tibial tunnel are as follows: the angle between tibial plateau and tibial tunnel is 37.0°±4.5°, and the perpendicular distances from the tibial tunnel entrance and exit point to the tibial plateau are (57.8±7.4) mm and (34.5±3.3) mm, respectively. Gender and body height are the important factors influencing the above measurement outcomes.

Posterior cruciate ligament (PCL) injury is common in sports medicine. Arthroscopic reconstruction of PCL has become a routine procedure to stabilize the knee joint after PCL injury. The location of tibial tunnel during operation is crucial to a successful surgery. This article reviews the current studies on transtibial PCL reconstruction from the aspects of the anatomy related to the tibial tunnel, the anteromedial and anterolateral tibial tunnels, the maximum angle and optimal angle of tibial tunnel, and the anatomical and non-anatomical tibial tunnels, hoping to provide helpful references for the treatment of PCL injury.

Transtibial tunnel reconstruction is one of the classical surgical techniques for posterior cruciate ligament (PCL) reconstruction. However, this surgical technique inevitably produces the "killer turn" effect. Specifically, during the transtibial tunnel reconstruction, there is a sharp tunnel edge at the exit of the tibial tunnel, and the graft has a large stress at this edge, which leads to the failure of transplantation due to the repeated friction between the graft and the tunnel edge. The "killer turn" effect may lead to the "residual laxity", thus resulting in postoperative knee instability, affecting the long-term efficacy of reconstructive surgery and reducing the postoperative satisfaction of patients. In recent years, many scholars have proposed a series of improved techniques for PCL reconstruction in dealing with the "killer turn" effect, including tibial inlay technique and improved transtibial tunnel technique. The authors review the formation mechanism of "killer turn" effect and methods to eliminate or reduce the effect, in order to provide a reference for improving the effect in PCL reconstruction.

Objective:To compare the efficacy of open surgery and arthroscopic assisted surgery in treatment of knee dislocations.Methods:A retrospective case-control study was conducted to analyze the clinical data of 80 patients with knee dislocations admitted to Second Hospital of Lanzhou University from May 2013 to September 2019, including 59 males and 21 females, aged 18-66 years [(42.5±11.6)years]. Open multiple ligament reconstruction was performed in 49 patients (open group) and arthroscopic assisted multiple ligament reconstruction was performed in 31 patients (arthroscopic group). The postoperative hospitalization days, incidence of complications, time needed for recovery of knee range of motion (>0°, >90°, >120°), and time to complete weight-bearing were compared between the two groups. The Lysholm score, international knee documentation committee (IKDC) subjective knee form, Tegner activity level, score of the MOS item short-form health survey (SF-36), patient satisfaction and knee range of motion were compared between the two groups at the last follow-up.Results:All the patients were followed up for 1.2-7.4 years [(3.8±1.5)years]. There was no significant difference in postoperative hospitalization days or incidence of complications between the two groups ( P>0.05). No significant difference was found in time needed for recovery of knee range of motion (>0°, >120°) or time to complete weight-bearing ( P>0.05). The time needed for recovery of knee range of motion (>90°) was 90(60, 90)days in open group and 60(30, 90)days in arthroscopic group ( P<0.05). At the last follow-up, there was no significant difference in Lysholm score, IKDC subjective score, Tegner activity level, SF-36 score, or patient satisfaction between the two groups ( P>0.05). At the last follow-up, the knee range of motion was 120°(90°, 130°) in open group and 135°(120°, 140°) in arthroscopic group ( P<0.05). Conclusion:For treatment of knee dislocations, open surgery and arthroscopic assisted surgery have similar results in the long-term effect, while arthroscopic assisted surgery has benefits in early rehabilitation and ultimately better knee range of motion.

Objective To localize the tibial attachment of the posterior cruciate ligament (PCL) on the magnetic resonance imaging (MRI) and provide parameters for clinical PCL reconstruction.Methods We retrospectively analyzed 524 patients with intact tibial PCL attachment who had undergone knee MRI from January 2010 to January 2016.They were 286 men and 238 women with an average age of 35 years (from 20 to 50 years).The size and positions of the tibial PCL attachment were measured on the sagittal and coronal MRI slices.The differences were analyzed between different genders.Results On the sagittal slices,the mean distance from the central tibial PCL attachment to the posterior edge of the tibial plateau was 17.9 ± 3.0 mm and the mean anteroposterior diameter of the tibial PCL attachment was 9.7 ± 2.4 mm,with those for males significantly larger than for females (P ＜ 0.05).The above mean values when expressed as a percentage of the posterior tibial slop were 79.9％ ±4.5％ and 43.7％ ± 9.6％,respectively,showing no significant differences between males and females (P ＞ 0.05).On the coronal slices,the distances from the central tibial PCL attachment to the medial and lateral edges of the tibial plateau were 33.5 ± 3.1 mm and 37.4 ±4.1 mm,respectively,and the mediolateral diameter of the tibial PCL attachment was 12.0 ± 1.6 mm,with those for males significantly larger than for females (P ＜ 0.05).The above mean values when expressed as a percentage of the mediolateral diameter of the tibial PCL attachment were 47.4％ ± 3.2％,52.7％ ±3.1％ and 16.9％ ± 1.7％,respectively,showing no significant differences between males and females (P ＞ 0.05).Conclusions On knee MRI images,the distance from the central tibial PCL attachment to the posterior edge of the tibial plateau is about 17.9 mm,the anteroposterior diameter of the tibial PCL attachment around 9.7 mm,and the mediolateral diameter of the tibial PCL attachment roughly 12.0 mm.These measurements for males are larger than for females.

Objective To investigate the osteogenic ability of dextran sulfate/recombinant human bone morphogenetic protein-2/chitosan (DS/rhBMP2/CS) nano microspheres combined with coralline hydroxyapatite (CHA) in repair of segmental bone defects.Methods DS/rhBMP2/CS microspheres prepared by ionic crosslinking method were adsorbed into CHA by lyophilization.Seventy-two New Zealand rabbits were randomly divided into 3 equal groups after they had been made into models of bone defect at the right radius.The defects in the 3 groups were implanted respectively with CHA,rhBMP2/CHA and DS/rhBMP2/ CS/CHA.Another 18 animals served as a blank control group.Blood and bone samples were obtained at 4,8 and 12 weeks after implantation.The serum BGP was detected,and the bone grafts were scanned by micro-CT for calculation of volume ratio of the new bone.Hematoxylin and eosin (HE) staining was performed after bone decalcification.Results All the 72 animals recovered well without any infection or graft exposure.Gross observation at postoperative 12 weeks showed that the DS/rhBMP2/CS/CHA group was the best in the quality,quantity and strength of the new bone,as well as in the healing of bone defects.The serum levels of bone gamma-carboxyglutamic-acid-containing protein at all time points in the DS/rhBMP2/CS/CHA group were significantly higher than those in the CHA and rhBMP2/CHA groups (P ＜ 0.05).Micro-CT scanning demonstrated obvious progress in bone formation,cortical bone and marrow cavity at all time points in the DS/rhBMP2/CS/CHA group which showed significantly faster bone reconstruction synchronized with material degradation and significantly higher volume ratio of the new bone than the other 2 groups (P ＜ 0.05).Histological examinations showed better morphology of mature cortical bone and new marrow cavity at all time points in the DS/rhBMP2/CS/CHA group than in the other 2 groups.Conclusion Since DS/rhBMP2/CS/CHA possesses a better mechanism of sustained-releasing rhBMP2 to induce bone formation because of its reticular and hole-hole-connected structure,it may perform better in repairing segmental bone defects than simple CHA or rhBMP2/CHA.

Objective To evaluate the application value of ultrasound in vascularization of different artificial bones . Methods A total of 15 New Zealand rabbits were utilized for model establishment of classic segmental bone defect in bilateral radius . Recombinant human bonemorphogenic protein-2 ( rhBMP-2 ) coralline hydroxyapatite(CHA) and CHA were implanted into left and right limbs . Each CHA was divided into 4 equal parts which were examined with conventional ultrasonography and contrast-enhanced ultrasonography( CEUS ) on 3 d ,7 d ,11 d ,15 d ,30 d and 45 d respectively . CEUS quantitative was performed by time-intensity curve(TIC) ,which parameters including the basic intensity(BI) ,peak intensity (PI) ,increased signal intensity ( ΔSI) and time to peak ( TTP) . Then the results were analyzed and compared to pathology . Results Within the same duration ,the vascularization degree in rhBMP-2 group was stronger than that in the ordinary group with advanced vascularization time . Positive correlation was detected between ΔSI and time of both groups ( r =0 .938 ,0 .890 ;P =0 .000) ,and negative correlation was found between BI/PI or TTP and time ( BI/PI: r = -0 .798 ,-0 .899 ; P = 0 .000 ;TTP= r -0 .874 ,-0 .868 ;P = 0 .000 ) . No statistical significance was observed among four observation points of both CHA ,which indicated no obvious difference in vascularization degree of each observation point . Conclusions The structure of bone graft can be clearly displayed by conventional ultrasound ,and CEUS is able to show the early blood perfusion in two CHA grafts and to accurately evaluate the difference of CHA microvascular growth before and after rhBMP-2 application . The combination of these two techniques is a promising approach of evaluating bone graft vascularization in clinical practice .

Objective To compare the biomechanical stability of 4 internal fixations in treatment of acetabular fracture of the lower anterior column through finite element analysis.Methods One normal adult male pelvis was subjected to 0.7mm thin-section CT scanning and 379 CT pictures were obtained.Finite element modeling software was used to establish internal fixation models for acetabular fracture of the lower anterior column,including lag screws (A),anterior column reconstruction plate (B),subcutaneous plate not crossing the pubic symphysis (C) and subcutaneous plate crossing the pubic symphysis (D).Finite element analysis was carried out to compare the biomechanical differences among the 4 internal fixation models which were subjected to the same loading conditions at both standing and sitting positions.Results At standing and sitting positions,the maximum displacement and the mean node displacement of fracture lines were the greatest in group A (0.558 mm and 0.462 ±0.092 mm at standing;0.634 mm and 0.473 ±0.108 mm at sitting),the smallest in group D (0.512 mm and 0.425 ±0.083 mm at standing;0.031 mm and 0.025 ± 0.004 mm at sitting),and in between in group B (0.513 mm and 0.432 ±0.085 mm at standing;0.630 mm and 0.466 ± 0.109 mm at sitting) and in group C (0.514 mm and 0.433 ± 0.085 mm at standing;0.627 mm and 0.464 ± 0.107 mm at sitting).At both standing and sitting positions,the maximum stress at the fracture line was the greatest in group D (10.519 MPa and 24.879 MPa),the smallest in group A (3.254 MPa and 8.954 MPa),and in between in group B (4.873 MPa and 9.431 MPa) and in group C (4.384 MPa and 10.128 MPa).Conclusions In treatment of acetabular fracture of the lower anterior column,subcutaneous plate crossing the pubic symphysis may result in the greatest biomechanical stability,lag screws the smallest biomechanical stability,and anterior column reconstruction plate and subcutaneous plate not crossing the pubic symphysis the moderate biomechanical stability.