Developing a Machine-Learning Predictive Model for Retention of Posterior Cruciate Ligament in Patients Undergoing Total Knee Arthroplasty.

OBJECTIVE: Predicting whether the posterior cruciate ligament (PCL) should be preserved during total knee arthroplasty (TKA) procedures is a complex task in the preoperative phase. The choice to either retain or excise the PCL has a substantial effect on the surgical outcomes and biomechanical integrity of the knee joint after the operation. To enhance surgeons' ability to predict the removal and retention of the PCL in patients before TKA, we developed machine learning models. We also identified significant feature factors that contribute to accurate predictions during this process. METHODS: Patients' data on TKA continuously performed by a single surgeon who had intended initially to undergo implantation of cruciate-retaining (CR) prostheses was collected. During the sacrifice of PCL, we utilized anterior-stabilized (AS) tibial bearings. The dataset was split into CR and AS categories to form distinct groups. Relevant information regarding age, gender, body mass index (BMI), the affected side, and preoperative diagnosis was extracted by reviewing the medical records of the patients. To ensure the authenticity of the research, an initial step involved capturing X-ray images before the surgery. These images were then analyzed to determine the height of the medial condyle (MMH) and lateral condyle (LMH), as well as the ratios between MLW and MMH and MLW and LMH. Additionally, the insall-salvati index (ISI) was calculated, and the severity of any varus or valgus deformities was assessed. Eight machine-learning methods were developed to predict the retention of PCL in TKA. Risk factor analysis was performed using the SHApley Additive exPlanations method. RESULTS: A total of 307 knee joints from 266 patients were included, among which there were 254 females and 53 males. A stratified random sampling technique was used to split patients in a 70:30 ratio into a training dataset and a testing dataset. Eight machine-learning models were trained using data feeding. Except for the AUC of the LGBM Classifier, which is 0.70, the AUCs of other machine learning models are all lower than 0.70. In importance-based analysis, ISI, MMH, LMH, deformity, and age were confirmed as important predictive factors for PCL retention in operations. CONCLUSION: The LGBM Classifier model achieved the best performance in predicting PCL retention in TKA. Among the potential risk factors, ISI, MMH, LMH, and deformity played essential roles in the prediction of PCL retention.

Constrained Condylar Prostheses for the Treatment of Charcot Arthropathy: A Case Report and Literature Review.

BACKGROUND: Neuroarthropathy of the knee or Charcot knee, leading to chronic joint destruction, is a rare disease that is difficult to diagnose. The treatment of this condition is difficult and controversial. CASE PRESENTATION: A 74-year-old Asian woman has had bilateral knee pain for 22 years and deformity for 10 years, which has been aggravating for 2 months. Physical examination showed bilateral knee varus deformity greater than 15°, and -20 to 90° range of motion. X-ray revealed bilateral varus deformity with massive free body hyperplasia. Combined with medical history as syringomyelia, the patient was diagnosed with bilateral Charcot knees and bilateral joint replacements were performed using Legacy Constrained Condylar Knee prostheses (LCCK; Zimmer, USA). The patient reported satisfactory treatment outcomes, pain relief, and improved range of motion in both knees, without postoperative complications or prosthesis loosening at 2 year after operation. CONCLUSIONS: Total knee arthroplasty (TKA) may be considered a viable option for treating the Charcot knee. The use of constrained condylar prostheses can produce satisfactory results. Attention should be given to survival risks, complications, and other potential determining factors associated with TKA when devising a treatment strategy for the Charcot knee.

Posterior-Stabilized Versus Cruciate-Retaining Prostheses for Total Knee Arthroplasty: An Overview of Systematic Reviews and Risk of Bias Considerations.

Background: Numerous systematic reviews have been published comparing the outcomes of patients undergoing posterior stabilized (PS) versus cruciate-retaining (CR) procedures in total knee arthroplasty (TKA), but with some overlaps and contradictions. The objectives of this study were (1) to perform an overview of current systematic reviews comparing PS versus CR in TKA, by evaluating their methodological quality and risk of bias, and (2) to provide recommendations through the best evidence. Methods: A systematic search of systematic reviews comparing PS and CR in TKA, published until June 2021 was conducted using the MEDLINE, EMBASE, and Cochrane Library databases. Included systematic reviews were assessed for methodological quality and risk of bias by the AMSTAR2 instrument and ROBIS tool, respectively. The choice of best evidence was conducted according to the Jadad decision algorithm. Results: A total of eight systematic reviews were eligible for inclusion in this study. The Jadad decision algorithm suggested that reviews with the highest AMSTAR2 scores should be selected. According to the ROBIS tool, there were three reviews with a low risk of bias and five with a high risk of bias. Consequently, one systematic review conducted by Verra et al. with the highest AMSTAR2 score and low risk of bias was selected as the best evidence. Conclusions: Although current systematic reviews demonstrated some statistical differences in clinical presentation and functional outcomes between PS and CR, the current outcome indicators cannot be taken to provide recommendations for undergoing PS or CR. The decision for prosthesis selection could be made mostly based on the surgeon's preference, indications and other indicators.

Preoperative Factors Predicting the Preservation of the Posterior Cruciate Ligament in Total Knee Arthroplasty.

OBJECTIVE: Predicting the successful preservation of posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) is an important step for preoperative planning to secure the satisfactory outcomes. We aimed to examine the preoperative factors predicting the successful preservation of the PCL in cruciate-retaining TKA and the outcome of sacrificing the PCL. METHODS: In this retrospective study, we analyzed TKAs consecutively performed by a single surgeon between January 2019 and August 2021 who had been preoperatively planned to undergo implantation of cruciate-retaining (CR) prostheses. The outcome of the current study was whether the PCL was retained or sacrificed. Anterior-stabilized (AS) tibial bearings when the PCL was sacrificed as needed were used intraoperatively. Age, sex, body mass index (BMI), and preoperative diagnosis from the patients' medical records were obtained. The medial-lateral width of epicondyle (MLW), the medial posterior condyle height (MPCH), the lateral posterior condyle height (LPCH), the ratio of MLW and MPCH, the ratio of MLW and LPCH, the Insall-Salvati index, and the severity of the varus or valgus deformity were measured using preoperative radiographs. Univariate and multivariate regression were fitted to assess the association of these factors with the successful retention of PCL. To examine the influence of sacrifice of the PCL on the surgical procedure, the size of the tibial and femoral components, the thickness of the polyethylene insert, and the rate of patella replacement between the CR group and AS group were also compared using t tests or chi-square tests. RESULTS: Among 307 TKAs included, PCL was sacrificed with concurrent use of AS prostheses in 89 (29.0%) procedures. Knees with rheumatoid arthritis (P < 0.01), lower Insall-Salvati index (P < 0.01), and more severe varus deformity (P = 0.011) were at a higher risk of sacrificing the PCL intraoperatively. There was no significant difference in age, sex, BMI, MLW, MPCH, LPCH, ratio of MLW and MPCH, ratio of MLW and LPCH, size of the tibial and femoral components, or replacement of the patella between the CR and AS groups. Converting from CR to AS was associated with a higher risk of using a thicker polyethylene insert (P < 0.01). CONCLUSION: Rheumatoid arthritis, lower Insall-Salvati index, and more severe varus deformity were associated with an increased risk of sacrificing the PCL in TKAs planned to undergo implantation CR prostheses. Converting to AS tibial bearing may result in a thicker polyethylene insert. These factors should be carefully considered for the appropriate selection of prosthesis type preoperatively.

Catastrophic Periprosthetic Osteolysis in Total Hip Arthroplasty at 20 Years: A Case Report and Literature Review.

BACKGROUND: Periprosthetic osteolysis is a serious complication following total hip arthroplasty (THA). However, most orthopedic surgeons only focus on bone loss and hip reconstruction. Thus, it was required to understand the treatment algorithm for periprosthetic osteolysis integrally. CASE PRESENTATION: A 52-year-old Asian male presented with chronic hip pain. A mass appeared on the medial side of the proximal left thigh at more than 20 years after bilateral THA. Radiographs revealed catastrophic periprosthetic osteolysis, especially on the acetabular side. Large amounts of necrotic tissue and bloody fluids were thoroughly debrided during revision THA. A modular hemipelvic prosthesis was used for revision of the left hip. Four years later, the patient presented with right hip pain, where a mass appeared on the medial side of the proximal right thigh. A primary acetabular implant with augment was used for revision of the right hip. Laboratory evaluation of bloody fluid retrieved from surgery revealed elevated levels of inflammatory markers. CONCLUSION: Inflammatory responses to polyethylene wear debris can lead to severe bone resorption and aseptic loosening in the long-term following THA. Therefore, in spite of revision THA, interrupting the cascade inflammatory might be the treatment principle for periprosthetic osteolysis.

Total Knee Arthroplasty for Fixed Valgus Deformity Correction Using a Modified Lateral Parapatellar Approach.

Total knee arthroplasty (TKA) for patients with valgus deformity (> 10 degrees) is technically challenging and has produced variable clinical results in terms of deformity correction, instability, and overall outcomes. The lateral parapatellar approach (LPA) is an alternative to the traditional medial parapatellar approach with potential advantages of direct access for release of tight lateral ligamentous structures with preservation of the medial structures, optimized patellar tracking, preserved medial blood supply to the patella, and less use of constrained implants. We present a case series of a single institution's experience with use of a modified LPA using a Z-capsuloplasty for 35 primary TKA cases in 30 patients with osteoarthritis and Ranawat's type-II fixed valgus deformity with attenuation of medial soft tissues. The mean age of patients was 64.8 years (range: 42-78 years). Follow-up duration was a mean of 47.3 months (range: 3-130 months). The patients were assessed pre- and postoperatively using radiographic measurement of the anatomic femorotibial angle (FTA) and clinical measurement of range of motion (ROM) and the Chinese knee society score (KSS). Complications and reoperations were recorded. The mean coronal alignment was corrected from 20.4 degrees of valgus (range: 11.3-42 degrees) preoperatively to 7.0 degrees of valgus (range: 3.6-15.1 degrees) postoperatively. One case required use of a constrained condylar design implant. At a mean of 47.3 months, the mean Knee Society objective and functional scores improved to 91.8 ± 6.6 and 84.3 ± 18.2 points, respectively. Mean ROM was 94.9 degrees preoperatively and 105.7 degrees postoperatively. Three cases (8.6%) had postoperative complications, including transient common peroneal nerve palsy, hematoma, and deep infection. One patient underwent two-stage revision for infection. There were no cases of late instability. The modified LPA using a Z-capsuloplasty is a reproducible and effective surgical technique for performing TKA in the setting of osteoarthritis and severe valgus deformity.

A Novel Method of Evaluating Knee Joint Stability of Patients with Knee Osteoarthritis: Multiscale Entropy Analysis with A Knee-Aiming Task.

Deteriorating knee stability is a local risk factor that reflects the occurrence and aggregative of osteoarthritis (OA). Despite the many biomechanics-based methods for assessing the structural stability of knee joints in clinics, these methods have many limitations. The stability of the knee joint relies on not only biomechanical factors, but also proprioception and the central nervous system. In this study, we attempt to depict the stability of knee joint from a holistic viewpoint, and a novel index of knee joint stability (IKJS) was thus extracted. We compared the differences of IKJS in 57 healthy volunteers and 55 patients with OA before and after total knee replacement (TKR). Analysis of Variance results demonstrated that there existed significant differences in IKJS among the three participating groups (<0.0001). Also, the IKJS of the operated leg in patients with knee OA increased remarkably after TKR (p < 0.0001). Furthermore, the results of the experiment suggested that the IKJS has sufficient reproducibility (ICC = 0.80). In conclusion, the proposed IKJS that employs the knee-aiming task is feasible for quantitatively determining knee stability. It can provide a potentially valuable and convenient tool to evaluate the effect of postoperative rehabilitation for patients with knee OA.

A target field design of open multi-purpose RF coil for musculoskeletal MR imaging at 3T.

Musculoskeletal MR imaging under multi-angle situations plays an increasingly important role in assessing joint and muscle tissues system. However, there are still limitations due to the closed structures of most conventional RF coils. In this study, a time-harmonic target-field method was employed to design open multi-purpose coil (OMC) for multi-angle musculoskeletal MR imaging. The phantom imaging results suggested that the proposed OMC could achieve homogeneously distributed magnetic field and high signal-to-noise ratio (SNR) of 239.04±0.83 in the region of interest (ROI). The maximum temperature in the heating hazard test was 16°C lower than the standard regulation, which indicated the security of the designed OMC. Furthermore, to demonstrate the effectiveness of the proposed OMC for musculoskeletal MR imaging, especially for multi-angle imaging, a healthy volunteer was examined for MR imaging of elbow, ankle and knee using OMC. The in vivo imaging results showed that the proposed OMC is effective for MR imaging of musculoskeletal tissues at different body parts, with satisfied B1 field homogeneity and SNR. Moreover, the open structure of the OMC could provide a large joint movement region. The proposed open multi-purpose coil is feasible for musculoskeletal MR imaging, and potentially, it is more suitable for the evaluation of musculoskeletal tissues under multi-angle conditions.

Effects of transcranial direct current stimulation (tDCS) on multiscale complexity of dual-task postural control in older adults.

Transcranial direct current stimulation (tDCS) targeting the prefrontal cortex reduces the size and speed of standing postural sway in younger adults, particularly when performing a cognitive dual task. Here, we hypothesized that tDCS would alter the complex dynamics of postural sway as quantified by multiscale entropy (MSE). Twenty healthy older adults completed two study visits. Center-of-pressure (COP) fluctuations were recorded during single-task (i.e., quiet standing) and dual-task (i.e., standing while performing serial subtractions) conditions, both before and after a 20-min session of real or sham tDCS. MSE was used to estimate COP complexity within each condition. The percentage change in complexity from single- to dual-task conditions (i.e., dual-task cost) was also calculated. Before tDCS, COP complexity was lower (p = 0.04) in the dual-task condition as compared to the single-task condition. Neither real nor sham tDCS altered complexity in the single-task condition. As compared to sham tDCS, real tDCS increased complexity in the dual-task condition (p = 0.02) and induced a trend toward improved serial subtraction performance (p = 0.09). Moreover, those subjects with lower dual-task COP complexity at baseline exhibited greater percentage increases in complexity following real tDCS (R = -0.39, p = 0.05). Real tDCS also reduced the dual-task cost to complexity (p = 0.02), while sham stimulation had no effect. A single session of tDCS targeting the prefrontal cortex increased standing postural sway complexity with concurrent non-postural cognitive task. This form of noninvasive brain stimulation may be a safe strategy to acutely improve postural control by enhancing the system's capacity to adapt to stressors.

Knee MRI under varying flexion angles utilizing a flexible flat cable antenna.

The aim of this study is to fabricate and test a novel flexible flat cable antenna (FFCA) for MRI of the knee at different flexion angles. The FFCA was made of a flat cable, a tuning/matching circuit and a signal transmission line. To test its feasibility and validity, in vitro and in vivo experiments were carried out on a 3.0 T MR scanner. The in vitro experiment suggested that the proposed FFCA could achieve a high signal-to-noise ratio (SNR) of 336, while the SNR of an eight-channel knee coil was 291, and phantom images from the FFCA are homogeneously distributed. In the in vivo experiment, the FFCA had a higher SNR of 169 in the region of interest and more than 48.5 cm of longitudinal coverage, while the corresponding values for the commercial coil were 153 and 22.5 cm. Finally, five sagittal knee images at different flexion angles were acquired. The FFCA could acquire satisfactory knee images at different flexion angles, with the advantages of simplicity, low cost, large field of view and high SNR. It may therefore be further used to improve MR image quality of the knee joint.

[Effects of varus of knee osteoarthritis on patellar position].

OBJECTIVE: To explore the effects of varus of knee osteoarthritis (OA) on patellar position. METHODS: A total of 19 patients (27 knees) underwent the examinations of anterior-posterior, lateral knee and axis of patellar X-ray at 30°, 45°, 60° and each X-ray was measured. RESULTS: The ratio between length of patellar tendon and length of patellar, vertical distance of lower edge of patellar to tibial plateau and height of patellar, distance of lower edge of medial facet of patellar to anterior angle of tibia and height of patellar were different from normal values. Patellar moved medially during the process of bending from 30°to 60°. CONCLUSION: The patellar of knee OA patients with varus moves down and medially.

[Effects of thromboprophylaxis duration on coagulation indicators after total hip replacement].

OBJECTIVE: To compare the effects of short-term and long-term thromboprophylaxis after total hip replacement on coagulation indicators in plasma sampled before and 1, 7 and 35 days post-operation. METHODS: A total of 40 patients scheduled for elective total hip replacement were randomly assigned into the short-term (n = 20) or long-term (n = 20) thromboprophylaxis groups on oral rivaroxaban 10 mg once daily for 7 or 35 days. The primary efficacy hemostatic variables included thrombin-antithrombin complexes (TAT), prothrombin fragment 1+2 (F1t2), D-dimer and fibrinogen (Fib) preoperatively and at Days 1, 7 and 35 postoperatively. And ultrasonography was performed on all patients preoperatively and at days 7 and 35 postoperatively to exclude deep vein thrombosis of lower extremities. RESULTS: None of them had deep vein thrombosis (DVT) of lower extremities. Among them, TAT, F1+2, D-dimer and Fib post-operation were higher than those preoperative baseline values. TAT and D-dimer peaked at day 1 postoperatively while the peaks of F1+2 and Fib appeared at day 7 postoperatively. At Day 35 post-operation, the levels of TAT and F1+2 in the long-term thromboprophylaxis group were significantly lower than those of the short-term thromboprophylaxis group (P < 0.05). CONCLUSION: The status of hypercoagulability may sustain at least 35 days after total hip replacement. Though not completely eliminated, it can still be reduced by prolonged thromboprophylaxis. However, according to ultrasonography, the effects of short-term and long-term thromboprophylaxis on the incidence rate of DVT remain to be further explored.

[Total knee arthroplasty by lateral parapatellar approach for valgus knee].

OBJECTIVE: To investigate the effect of lateral parapatellar approach in total knee arthroplasty (TKA) of valgus knee. METHODS: Lateral parapatellar approach of total knee arthroplasty was applied in 8 patients (10 knees) with severe valgus osteoarthritis knee (bilateral in 2 cases and unilateral in 6 cases), with the valgus angle > 15 degrees , 1 male (1 knee) and 7 females (9 knee), aged 68.2 (58 - 79), 7 cases (9 knees) being of the Krackow type I and 1 case (1 knee) of the Krackow type I, I. After incision of the skin through lateral knee, ilio-tibial band was prolonged by apple pie arthroplasty. The joint capsule was cut open laterally 2 - 4 cm from the para-patellar edge. Soft tissue balance was performed by releasing I - T band in Gerdy tubercle, lateral collateral ligament and poster-lateral capsule from the femur and tibial side. Valgus angle of distal femur cutting were five degree. Whiteside line and trans-epicondylar line were used as AP rotational cutting reference. All patellar of the group were resurfaced. Capsule closure is completed with the knee flexed. The expanded deep lateral soft tissue sleeve (coronal Z-plasty) is sutured with the medial retinaculum sleeve (superficial layer). Follow-up was conducted for 19.6 months (1 - 51 months). RESULTS: Seven cases (9 knees) were replaced by posterior stabilized cemented prostheses (TC-Dynamic, PLUS), one case (1 knee) was replaced by RT prosthesis (RT-PLUS(TM) Solution, PLUS). After operation, the valgus deformity of all patients was corrected and all patients could walk 100 m with or without the help of walking holders. The average range of motion (ROM) was improved from the pre-operative. 95.6 degrees (85 degrees - 110 degrees ) to the post-operative 117.1 degrees (100 degrees - 125 degrees ). The average femorotibial angle (FTA) was corrected from the pre-operative. 27.6 degrees (20 degrees - 40 degrees ) to the post-operative 6.8 degrees (5 degrees - 9 degrees ). The Knee Score System (KSS) score and functional score were improved from the pre-operative 22.7 points (9 - 48 points) and 26.5 points (12 - 55 points) to the post-operative 86.4 points (85 - 95 points) and 89.1 points (80 - 95 points) respectively. Follow-up showed that the FTA remained unchanged and the knee stability of all patients was good. CONCLUSION: Through lateral approach, "Z" plasty of the capsule can release the lateral structure and decrease the pressure of common peroneal nerve. For TKR with moderate to severe fixed valgus knee, lateral approach is an effective way to correct the deformity.

[Relationship between anatomy of knee collateral ligament and geometry of posterior femoral condylar articular surface].

OBJECTIVE: To analyze the relationship between the collateral ligament attachment and the epicondylar axis with rotational alignment of the femoral component in the total knee arthroplasty(TKA). METHODS: Twenty normal cadaver knee joints were anatomized and 2 holes were drilled on the distal femur from the deep and superficial insertions of the medial collateral ligaments to the lateral condylar part, respectively. Then, all the knees were scanned by MRI on the sagittal plane, making the drilled hole located relatively to the posterior condylar joint surface on the axial plane, and the posterior condylar angle (PCA) and the condylar twist angle (CTA) were measured. RESULTS: The collateral ligament had the deep and superficial parts, and the deep part was strained during the knee flexing. PCA and CTA were 4.50 +/- 1.26 degrees and 7.10 +/- 0.30 degrees respectively, and there was a significant difference between them (P < 0.05), which were significantly greater than those reported abroad. On the sagittal plane, there was no significant difference between the radius of the posterior medial and lateral condylar circles (P > 0.05). The distance from the center of the posterior condylar circle to the deep insertion of the medial collateral ligament (MCL) (dl) was 4.22 +/- 0.20 mm, and the distance to the superficial insertion of MCL (d2) was 7.36 +/- 0.13 mm. The difference between dl and d2 was significant (P < 0.05). CONCLUSION: The center of the posterior condylar circle passes from the deep insertion of the collateral ligament, which can be regarded as a fixed flexion-extension axis of the knee. By releasing the different parts of the collateral ligaments, the balance of the flexion and extension gap can be obtained, and then varus, valgus or flexed contracture deformity of the knee can be realigned. Besides, the rotational orientation of the femoral prosthesis can be made by a reference to the epicondylar insertion of the collateral ligament.

[Techniques of soft tissue balance in total knee arthroplasty of varus knee].

OBJECTIVE: To analyze formation of the varus angle of the knee due to osteoarthritis and to explore techniques of the soft tissue balance in the total knee arthroplasty(TKA). METHODS: One hundred patients with 145 varus knees (18 males, 25 varus knees; 82 females, 120 varus knees) underwent TKA from January 1999 to December 2003. Their ages averaged 62.4 years (range, 45-80 years), and their HSS(hospital of special surgery)scores were 38.0 +/- 3.2 points. Before operation,all the patients were measured in the alignment of the lower extremity, accurate bone-cutting was performed, and their static alignment was achieved. Then, the soft tissue release was made. The release performance consisted of 3 steps: release before the bone-cutting, release during the bone-cutting, and release after the bone-cutting. Release of the medial ligament and capsule, elimination of the osteophytes, and release of the lateral patellar retinaculum were more important. RESULTS: The varus angles in these patients were 9.2 +/- 3.1 degrees before operation. Among them, the varus angles caused by the soft tissue imbalance accounted for 53.2%, and caused by the bone structure accounted for 46.8%; and the latter caused by the tibia varus, 22.8%, and by the tibia plateau destruction, 24.0%. There was no significant difference between the varus angles caused by the soft tissue imbalance and the varus angles caused by the bone structure deformity (P > 0.05). According to the postoperative imaging studies, the correction degree for the varus angles by the bone-cutting was 4.3 degrees, which represented 27.9% of the total corrected angles, and the correction degree for the varus angles corrected by the soft tissue balance was 10.7 degrees, which represented 72.1% of the total corrected angles. The HSS scores were 87.0 +/- 4.5 points after operation, and the difference between preoperation and postoperation was significant. CONCLUSION: The varus knee due to osteoarthritis results from the varus angle in the bone structure and the angles caused by the imbalance of the collateral ligaments and the soft tissues around the knee. The latter causative factor is more important in the formation of the varus knee and should only be corrected through the soft tissue release. The more important part to be released is the attachments of the medial ligament and the posterior capsule. The release performance should be followed by the principles, i.e., step by step, tests at all the time, and avoidance of the excessive release.

Segmental instability in cervical spondylotic myelopathy with severe disc degeneration.

STUDY DESIGN: A retrospective study was conducted. OBJECTIVE: To investigate relationships between severe disc degeneration (SDD) and segmental instability in cervical spondylotic myelopathy (CSM) and to discuss surgical treatment for CSM with severe disc degeneration. SUMMARY OF BACKGROUND DATA: Information on relationships between segmental instability and spinal cord compression in CSM with severe disc degeneration is scarce. METHODS: Radiographs and magnetic resonance images of patients with CSM with (n = 42) and without (n = 75) SDD were reviewed retrospectively. Cervical instability and spinal cord compression factors were analyzed. Outcomes of anterior cervical decompression and fusion (ACDF) and expansive laminoplasty (ELAP) were evaluated in medical records of follow-up clinics. RESULTS: Segmental instability was found in 71.4% of patients with SDD and 22.7% of patients without SDD. Spinal cord compression was found at the intervertebral space of SDD and upper adjacent disc space. The recovery rate of ACDF and ELAP was 60.8% and 57.1%, respectively. CONCLUSION: The upper adjacent vertebra above SDD has inclination of segmental instability. There is static spinal cord compression in intervertebral spaces of SDD and dynamic compression in upper adjacent intervertebral spaces. Multilevel anterior cervical decompression and fusion or expansive laminoplasty should be used for surgical treatment.

[Total knee replacement in valgus knee].

OBJECTIVE: To investigate the methods and clinical results of total knee replacement (TKA) in patients with valgus knee deformity. METHODS: Between January 1996 and August 2004, 87 TKAs were performed by means of medial parapatellar approach, standard osteotomy and only lateral soft tissue release with posterior stabilized implants on 74 patients (11 men and 63 women) with valgus deformity. The average age at the time of operation was 62.93 years (range, 26-80 years). Clinical and radiographic evaluations including range of motion (ROM), Knee Society Score System (KSS) and the tibial and femur angle (T-F angle) were performed at follow-up. RESULTS: After a mean follow-up of 33.8 months (range, 5 months-9 years), the average ROM improved from 91 degrees (range, 70 degrees-120 degrees) preoperatively to 112.4 degrees (range, 80 degrees-130 degrees) postoperatively, the average KSS improved from 22.7 points (0-48 points) preoperatively to 81.7 points (range, 71-93 points) postoperatively. The average function score improved from 26.5 points preoperatively to 86.3 points postoperatively, the average T-F angle was corrected from 21.59 degrees (range, 12 degrees-40 degrees) of valgus preoperatively to 8.7 degrees (0 degrees-11 degrees) of valgus postoperatively. One knee had lightly instability at follow-up, one knee with patellar dislocation preoperatively had subdislocation postoperatively, no other complication occurred. CONCLUSIONS: The techniques of medial parapatellar approach, standard osteotomy and only lateral soft tissue release with posterior stabilized implants can correct a fixed valgus deformity very successfully in patients undergoing primary total knee replacement, and provides excellent results.

[A comparison study of interbody cage in lumbar degenerative disease].

OBJECTIVE: To compare the advantages and disadvantages of TFC/BAK, Prospace and Brantigan I/F carbon cages and summarize their applications. METHODS: One hundred and twelve cases of Brantigan I/F, 123 cases of TFC/BAK and 45 cases of Prospaces were used in the treatment of degenerated lumbar disorders. The clinical results and complications were observed and analyzed. RESULTS: All devices restored the height of intervertebral space and achieved immediate stability after insertion. One hundred and twelve cases of Brantigan I/F cages were solid fused, the clinical results were satisfactory. Three cases of TFC/BAK cages subsided into the vertebra and 2 cages retropulsed slightly during follow-up. There was no serious complications of nervous system, but the operation time and amount of bleeding in Brantigan I/F group increased. CONCLUSIONS: Carbon fiber intervertebral cages are an effective method in treating degenerated lumbar disorders. To avoid complications, the indications and techniques must be selected carefully.