Alendronate use in older patients with reduced renal function: challenges and opportunities in clinical practice.

In this retrospective cohort study, alendronate use among older osteoporosis patients (age>65 years) with reduced renal function (creatinine clearance<35ml/min) was not associated with significant deterioration in renal function from baseline nor increased incidence of osteoporotic fractures or acute kidney injury, compared with patients conservatively managed with only calcium/vitamin D supplementation. INTRODUCTION: Oral bisphosphonates are not recommended in patients with creatinine clearance (CrCl) <35ml/min, although this is not supported by post hoc analyses of pivotal oral bisphosphonate studies. As both osteoporosis and renal insufficiency are more prevalent with advancing age, it is important to determine the safety and efficacy of oral bisphosphonates among these patients. METHODS: Patients with CrCl <35ml/min on alendronate (group A, n=98), with CrCl <35ml/min conservatively managed (group B, n=96), and with CrCl ≥35ml/min on alendronate (group C, n=96) were followed up to 22 months. Primary outcomes were mean change in CrCl from baseline in group A compared with groups B and C, respectively. Secondary outcomes were the incidence of osteoporotic fractures and adverse events between groups. RESULTS: There was no significant change in CrCl from baseline when comparing group A (-1.53±6.83ml/min) with group B (0.59±5.17ml/min) (p=0.075), and group A with group C (-3.71±7.54ml/min) (p=0.163). There was no significant increase in incidences of osteoporotic fractures in group A compared with group B (adjusted relative risk (aRR) 2.02, 95% confidence interval (CI) 0.64-6.37) and group A compared with group C (aRR 1.15, 95% CI 0.46-2.89). There was no significant difference in incidences of acute kidney injury (AKI) in group A compared with group B (aRR 0.48, 95% CI 0.20-1.12). Although statistically non-significant, there was an increase in AKI incidence in group A compared with group C (RR 7.84, 95% CI 0.98-62.66). CONCLUSION: Among patients with CrCl <35ml/min, alendronate therapy was not associated with significant deterioration in renal function from baseline. Although not powered for secondary outcomes, there were no statistically significant differences in osteoporotic fracture or AKI incidence between the groups.

Management of traumatic patellar dislocation in a regional hospital in Hong Kong.

INTRODUCTION: The role of surgery for acute patellar dislocation without osteochondral fracture is controversial. The aim of this study was to report the short-term results of management of patellar dislocation in our institute. METHODS: Patients who were seen in our institution with patella dislocation from January 2011 to April 2014 were managed according to a standardised management algorithm. Pretreatment and 1-year post-treatment International Knee Documentation Committee score, Tegner activity level scale score, and presence of apprehension sign were analysed. RESULTS: A total of 41 patients were studied of whom 20 were first-time dislocators and 21 were recurrent dislocators. Among the first-time dislocators, there was a significant difference between patients who received conservative treatment versus surgical management. The conservative treatment group had a 33% recurrent dislocation rate, whereas there were no recurrent dislocations in the surgery group. There was no difference in Tegner activity level scale score or apprehension sign before and 1 year after treatment, however. Among the recurrent dislocators, there was a significant difference between those who received conservative treatment and those who underwent surgery. The recurrent dislocation rate was 71% in the conservative treatment group versus 0% in the surgery group. There was also significant improvement in International Knee Documentation Committee score from 67.7 to 80.0 (P=0.02), and of apprehension sign from 62% to 0% (P<0.01). CONCLUSIONS: A management algorithm for patellar dislocation is described. Surgery is preferable to conservative treatment in patients who have recurrent patellar dislocation, and may also be preferable for those who have an acute dislocation.

Anterior cruciate ligament tear in Hong Kong Chinese patients.

OBJECTIVE: To investigate the associations between patient sex, age, cause of injury, and frequency of meniscus and articular cartilage lesions seen at the time of the anterior cruciate ligament reconstruction. SETTING: University affiliated hospital, Hong Kong. PATIENTS: Medical notes and operating records of 672 Chinese patients who had received anterior cruciate ligament reconstruction between January 1997 and December 2010 were reviewed. Data concerning all knee cartilage and meniscus injuries documented at the time of surgery were analysed. RESULTS: Of the 593 patients, meniscus injuries were identified in 315 (53.1%). Patients older than 30 years were more likely to suffer from meniscal injury compared with those younger than 30 years (60% vs 51%, P=0.043). Longer surgical delay was observed in patients with meniscal lesions compared with those without (median, 12.3 months vs 9.1 months, P=0.021). Overall, 139 cartilage lesions were identified in 109 (18.4%) patients. Patients with cartilage lesions were significantly older than those without the lesions (mean, 27.6 years vs 25.1 years, P=0.034). Male patients were more likely to have chondral injuries than female patients (20.1% vs 10.9%, P=0.028). The risk of cartilage lesions was increased by nearly 3 times in the presence of meniscal tear (P<0.0001; odds ratio=2.7; 95% confidence interval, 1.7-4.2). CONCLUSIONS: Increased age and surgical delay increased the risk of meniscal tears in patients with anterior cruciate ligament tear. Increased age, male sex, and presence of meniscal tear were associated with an increased frequency of articular lesions after an anterior cruciate ligament tear.

Smokers Achieved Minimal Clinically Important Difference for Visual Analog Scale and American Shoulder and Elbow Surgeons Scores at a Lower Rate Than Nonsmokers Even When Repaired Supraspinatus Tendons Were Intact on Postoperative Magnetic Resonance Imaging.

Purpose: To investigate the impact of smoking on clinical outcomes after repair of supraspinatus tendon in patients who had an intact repair found on postoperative magnetic resonance imaging. Methods: Patients who received primary complete repair of supraspinatus tendon tear between 2014 and 2020 were retrospectively identified. Patients were excluded if a postoperative magnetic resonance imaging scan was not available or if the follow-up was less than 2 years. Visual analog score (VAS), American Shoulder and Elbow Surgeons (ASES) score, and active forward flexion were assessed at the 2-year follow-up. The percentage of patients acquiring minimal clinically important difference (MCID) was reported. Results: One hundred primary supraspinatus tendon repairs were included. The healing rate was 77% in smokers and 90% in nonsmokers. Smoking was the independent predictor of a poorer 2-year VAS (P < .001) and ASES (P < .001) scores. Significant improvement in clinical outcomes was observed between preoperation and the 2-year follow-up, regardless of the integrity of the repair or smoking status (P < .001). When the repaired tendon was intact, nonsmokers had a greater chance of achieving MCID in 2-year VAS and ASES scores than smokers. Ninety-nine percent of nonsmokers, compared with 82% of smokers, achieved MCID in VAS at the 2-year follow-up (P = .023). The corresponding figures for ASES were 98% and 71%, respectively (P = .004). Conclusions: In this study, smoking was associated with poorer clinical outcomes, including a greater 2-year VAS pain score and a lower 2-year ASES score, when compared with nonsmokers, even in cases in which there was no full-thickness retear of the repaired supraspinatus tendon. Level of Evidence: Level III, retrospective cohort study.

Differences in Clinical Outcomes Between Patients With Retear After Supraspinatus Tendon Repair and Those With Intact Repair at 5-Year Follow-up.

BACKGROUND: It is well known that rotator cuff repair is associated with an overall retear rate of 21% to 26%. However, a cuff retear may not necessarily be associated with poor clinical outcomes. HYPOTHESIS: There would be no difference in clinical outcomes between patients with a cuff retear and those with an intact repair at a midterm follow-up of 5 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective study was conducted involving patients who received arthroscopic complete repair of the supraspinatus tendon between January 2009 and December 2017. Patients who did not have a postoperative magnetic resonance imaging (MRI) scan or who had a follow-up of <5 years were excluded. Clinical outcomes, including the visual analog scale (VAS) score, American Shoulder and Elbow Surgeons (ASES) score, and active forward flexion (FF) of the involved shoulder were assessed at the 2-year and 5-year follow-up points. RESULTS: The study group included 105 patients with a mean follow-up of 85 months. MRI scans were performed at a mean of 20 months. Fourteen full-thickness cuff retears and 91 intact repairs were identified using postoperative MRI scans. Significant improvement in VAS score, ASES score, and FF were found between the preoperative assessment and the 2 designated follow-up points (2 years and 5 years) in both the cuff retear and the intact repair groups (P < .001). The VAS and ASES scores at the 2-year follow-up for the intact repair group were 1.8 ± 2.0 and 80.7 ± 18.1, respectively. The corresponding values for the retear group were 2.3 ± 2.2 and 71.9 ± 19.5, respectively. No significant difference was found between the 2 groups in the VAS and ASES scores at the 2-year follow-up. However, patients with an intact repair had a better VAS score (1.4 ± 1.8; P = .049) and ASES score (81.7 ± 17; P = .019) than those with a cuff retear at the 5-year assessment (3.0 ± 2.8 and 67.1 ± 22.9, respectively). In the intact repair group, 91% of patients achieved the minimal clinically important difference for the 5-year VAS score, compared with 54% in the cuff retear group (P < .001). The corresponding values for the 5-year ASES score were 80% and 54%, respectively (P = .044). FF measurements at the 5-year follow-up in patients with intact repair and those with a cuff retear were 161°± 23° and 144°± 37°, respectively (P = .059). Continuous improvement in VAS score and FF between the 2-year and 5-year follow-up was observed in the intact repair group (P = .005 and P = .04, respectively). CONCLUSION: The patients with an intact repair had better VAS and ASES scores compared with those who had a cuff retear at a midterm follow-up of 5 years. Between the 2-year and the 5-year follow-up, some further improvement was observed in the VAS score and FF in the intact repair group.

Evaluation of Graft Maturation by MRI in Anterior Cruciate Ligament Reconstruction With and Without Concomitant Anterolateral Ligament Reconstruction.

Background: Single-bundle anterior cruciate ligament reconstruction (SB-ACLR) with concomitant anterolateral ligament reconstruction (ALLR) has been associated with better clinical results when compared with isolated SB-ACLR. However, it is not known whether the improved outcomes are the result of the influence of concomitant ALLR on ACL graft healing. Purpose/Hypothesis: The purpose of this study was to determine whether concomitant ALLR is associated with improved graft ligamentization after SB-ACLR. It was hypothesized that ALLR would not affect graft healing. Study Design: Cohort study; Level of evidence, 3. Methods: A 1 to 1 matching study was conducted on a consecutive series of 732 patients who underwent ACLR using a hamstring tendon autograft between 2007 and 2019. Patients were excluded if they had skeletal immaturity, inflammatory joint disease, multiple ligament reconstruction (other than ALLR), or a graft rupture. Patients with concomitant SB-ACLR and ALLR (SB-ACLR/ALLR) and isolated SB-ACLR were matched 1 to 1 based on age, sex, examination under anesthesia (EUA) grade 3 pivot shift, EUA grade 3 anterior drawer test, presence of graft impingement, sagittal graft angle, skeletal maturity, lack of generalized ligamentous laxity, and multiple ligamentous injury. A total of 40 matched pairs underwent postoperative magnetic resonance imaging (MRI) within the second year after surgery to assess graft ligamentization, which was measured by the signal-to-noise quotient (SNQ) of the ACL graft. Results: The mean follow-up period was 41 months, with a 2-year follow-up rate of 80% in the SB-ACLR/ALLR group and 98% in the isolated SB-ACLR group. The mean duration between the index operation and MRI was 16.4 ± 3.4 months. No significant difference was observed in the SNQ of the ACL graft between the SB-ACLR/ALLR and SB-ACLR groups (6.9 ± 4.6 vs 5.2 ± 4.8, respectively; P = .066). Conclusion: Study findings indicated that a concomitant ALLR at the time of hamstring tendon autograft ACLR did not affect graft healing as assessed by the SNQ of the ACL graft.

Distal femur rotation relates to joint obliquity in ACL-deficient Chinese.

BACKGROUND: The lower limb osteometry of Chinese differs from that of whites. The joint line of the knee in the coronal plane in Chinese is more medially inclined and the posterior condylar angle of the distal femur in the axial plane is larger. However, it is unclear whether there is any direct association between the coronal plane and axial plane osteometry. QUESTIONS/PURPOSES: We asked whether the joint line obliquity of the knee is related to the posterior condylar angle of the distal femur in young Chinese subjects. METHODS: Ninety-nine young Chinese patients with anterior cruciate ligament injuries were recruited. The lower limb alignment and joint line obliquity were measured using standing long radiographs of the whole lower limb. The rotational alignment of the distal femur was assessed in the axial cuts of the MRI. RESULTS: The distal femur rotational alignment was associated with the obliquity of the knee in Chinese. The posterior condylar angle was 5° ± 2°. The knee was 5° ± 3° medially inclined. CONCLUSIONS: The joint line of the knee in a group of young Chinese patients was more medially inclined than that of whites. The posterior condylar angle of the distal femur was larger. The presence of an association between distal femur rotational alignment and joint line obliquity in this group of young Chinese patients suggests a possible developmental cause explaining the difference in osteometry between races.

Tunnel positions in transportal versus transtibial anterior cruciate ligament reconstruction: a case-control magnetic resonance imaging study.

PURPOSE: The purpose of this study was to examine the difference in the position of bone tunnels prepared by the transportal technique versus the transtibial technique in anterior cruciate ligament (ACL) reconstruction. METHODS: A consecutive series of 42 patients receiving single-bundle ACL reconstructions were recruited between July 1, 2007, and December 31, 2008. The preparations of the femoral tunnel were performed by the transtibial technique in the first 21 cases and by the transportal technique in the subsequent 21 cases. Magnetic resonance imaging examination was performed in 39 patients (93%) 1 year after the index operation (20 transtibial and 19 transportal). Optimal tunnel position was defined as a lateralized femoral tunnel at a position of less than 11 o'clock for a right knee or more than 1 o'clock for a left knee, an adequate posteriorized femoral tunnel in the fourth quadrant of the modified Bernard line, and a tibial tunnel located in the second quadrant of the modified Amis line. RESULTS: The average clock position was 10:18 in the transportal group and 10:54 in the transtibial group (P < .001). Five outliers were found in the transtibial group but none in the transportal group. Concerning the femoral tunnel position on the sagittal-cut magnetic resonance imaging scan, the average position along the modified Bernard line was 74% in the transportal group and 69% in the transtibial group (P = .029). Concerning the tibial tunnel position, the average tibial tunnel positions along the modified Amis line were 47% and 52%, respectively (P = .019). CONCLUSIONS: The adoption of the transportal technique in single-bundle ACL reconstruction produced improved positions in both the femoral and tibial tunnels when compared with the transtibial technique. LEVEL OF EVIDENCE: Level III, case-control study.

Delay in ACL reconstruction is associated with more severe and painful meniscal and chondral injuries.

PURPOSE: The goal of our study was to investigate the associations between surgical delay, pain and meniscus, and articular cartilage lesions seen at the time of ACL reconstruction. METHODS: One hundred and sixty-two consecutive patients who had received ACL reconstruction were recruited. The preoperative International Knee Documentation Committee (IKDC) questionnaires, and cartilage and meniscal lesions seen at the time of surgery were analysed. RESULTS: Patients with surgery within 12 months were less likely to have meniscus injury (59.8/77.4 %, p = 0.032), and the meniscus injury was more likely to be salvageable. (56.3/36.0 %, p = 0.042). Patients with meniscal tear larger than 10 mm had higher pain intensity than tear <10 mm (mean 6.8/8.2, p = 0.007). Patients older than 35 years of age were more likely to suffer from cartilage injury (76.4/39.1 %, p = 0.004). Patients with cartilage lesions had longer surgical delay (mean 18.9/12.1 months, p = 0.033). The presence of meniscal tear increased the risk of cartilage lesions (p = 0.038, OR = 2.14). Patients with cartilage lesions had a greater pain frequency (mean 6.9/7.7, p = 0.048). Moderate correlation was found between the size of cartilage lesion and the frequency of pain (p = 0.013). CONCLUSIONS: Increased surgical delay was associated with an increased incidence of meniscus and articular cartilage injuries in patients suffering from ACL tear; also, the meniscus was less likely to be salvageable. The presence of cartilage lesions was associated with an increased frequency of pain. Size of meniscal and cartilage lesions was significantly associated with pain.

Early results of all-inside meniscal repairs using a pre-loaded suture anchor.

OBJECTIVES: To report the clinical and radiological results of all-inside meniscal repairs using a pre-loaded suture anchor. DESIGN: Case series. SETTING: Regional hospital, Hong Kong. PATIENTS: From January 2008 to June 2010, 51 patients with a mean age of 26 (range, 15-48) years with 57 meniscal tears underwent meniscal repair utilising the all-inside meniscal repair technique entailing a pre-loaded suture anchor. All tears were located at red-red or red-white zones. Concurrent anterior cruciate ligament reconstruction was performed in 37 (73%) of the patients. Patients were evaluated postoperatively based on the International Knee Documentation Committee score, clinical examination, and magnetic resonance imaging. Presence of locking, joint-line tenderness, effusion, and positive McMurray test were considered to indicate clinical failure. RESULTS: The mean follow-up was 19 (range, 12-39) months. An average of 2 (range, 1 to 4) suture devices was used per patient. The mean tear size was 20 (range, 10-40) mm. In all, 10 (18%) of the tears had failed clinically and 11 (19%) appeared unhealed on postoperative imaging. The mean International Knee Documentation Committee score improved significantly from 62 preoperatively to 81 postoperatively (P<0.001). Patients with concurrent anterior cruciate ligament reconstruction had better corresponding scores postoperatively than preoperatively (mean, 83 vs 65, P<0.001). The clinical and radiological outcome was not related to the chronicity, location or length of the tear, or patient age. No postoperative extra- or intra-articular complications were encountered. CONCLUSION: All-inside meniscal repair using a pre-loaded suture anchor is safe and effective, and yielded an 83% clinical and 81% radiological success rate.

Repair of meniscus root tear - Is there a difference between medial meniscus root repair and lateral meniscus root repair? A systematic review and meta-analysis.

PURPOSE: Complete meniscus root tear is associated with meniscus extrusion; this causes a loss of meniscus function and accelerated osteoarthritis of the knee. Existing small-scale retrospective case-control studies suggested that the outcomes were different between medial and lateral meniscus root repair. This meta-analysis aims to study whether such discrepancies exist via a systematic review of the available evidence in the literature. METHODS: Studies evaluating the outcomes of surgical repair of posterior meniscus root tears, with reassessment MRI or second-look arthroscopy, were identified through a systematic search of PubMed, Embase, and Cochrane Library. The degree of meniscus extrusion, healing status of the repaired meniscus root, and functional outcome scores after repair were the outcomes of interest. RESULTS: Among the 732 studies identified, 20 studies were included in this systematic review. 624 knees and 122 knees underwent MMPRT and LMPRT repair, respectively. The amount of meniscus extrusion following MMPRT repair was 3.8 ± 1.7 mm, which was significantly larger than the 0.9 ± 1.2 mm observed after LMPRT repair (p < 0.001). Significantly better healing outcomes were observed on reassessment MRI after LMPRT repair (p < 0.001). The postoperative Lysholm score and IKDC score was also significantly better after LMPRT than MMPRT repair (p < 0.001). CONCLUSIONS: LMPRT repairs resulted in significantly less meniscus extrusion, substantially better healing outcomes on MRI, and superior Lysholm/IKDC scores, when compared to MMPRT repair. This is the first meta-analysis we are aware of that systematically reviews the differences in the clinical, radiographic, and arthroscopic results of MMPRT and LMPRT repair.

Evaluation of Graft Ligamentization by MRI After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: The tendon graft used in anterior cruciate ligament reconstruction (ACLR) undergoes "ligamentization" after implantation, and the reported length of this process varies from 6 to 48 months. Some grafts have ruptured at subsequent follow-up evaluations. Although the progress of graft ligamentization can be followed with postoperative magnetic resonance imaging (MRI) for reassessment, it is not known whether a delay in ligamentization (as reflected by a higher signal of the graft) is associated with an increased chance of subsequent graft rupture. HYPOTHESIS: Signal intensity of the graft on reassessment MRI (signal-noise quotient [SNQ]) would be associated with the incidence of future graft rupture at subsequent follow-up. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 565 ACLRs with intact graft on first-time reassessment MRI after surgery were followed for a mean period of 67 months. The rates of 1-year and 2-year follow-up were 99.5% and 84.5%, respectively. The signal intensity of the intact graft on the first-time reassessment MRI was evaluated (1) quantitatively by the SNQ and (2) qualitatively with the modified Ahn classification. Among the 565 ACLRs, 23 additional graft ruptures developed during a time interval of 7 months to 9 years after the surgery. RESULTS: Higher SNQ was associated with increased chance of subsequent graft rupture (SNQ 7.3 ± 6 for subsequent graft rupture vs 4.4 ± 4 for grafts without subsequent rupture; P = .004, Mann-Whitney U test). The other important confounders that were associated with increased chance of graft rupture were younger age at the time of ACLR (P < .001) and longer follow-up time (P = .002). Multiple linear regression showed that all 3 factors (higher SNQ, younger age, and longer follow-up) were independent predictors of graft rupture (SNQ, P = .03; age, P < .001; follow-up, P = .012). When the reassessment MRI was performed in the second year after ACLR, the odds ratio of future graft rupture of a heterogeneous hyperintense graft when compared with a homogeneous hypointense graft was 12.1 (95% CI = 2.8 to 52.6) P < .001, Fisher exact test). CONCLUSION: Higher signal intensity of the intact graft on reassessment MRI (higher SNQ and heterogeneous hyperintense graft) was associated with increased chance of subsequent graft rupture.

Association of Smoking With Graft Rupture After Anterior Cruciate Ligament Reconstruction.

Background: The effect of smoking on graft rupture after anterior cruciate ligament (ACL) reconstruction is not well understood. Hypothesis: It was hypothesized that there will be no relationship between tobacco use and graft rupture after ACL reconstruction, as reflected by postoperative magnetic resonance imaging (MRI) and arthroscopic examination. Study Design: Cohort study; Level of evidence, 3. Methods: Included were 233 patients who received primary ACL reconstruction with hamstring tendon autograft between January 1, 2013, and December 31, 2019, and who underwent MRI evaluation at 20.2 ± 1.9 months postoperatively. The patients were categorized by smoking history into 2 groups: 39 smokers and 194 nonsmokers. The 2 groups did not differ significantly in age, sex, operative technique, preinjury Tegner score, or mean time until postoperative MRI. The primary outcome was graft rupture rate, with rupture confirmed by either arthroscopic assessment or postoperative MRI diagnosis. The secondary outcome measure was degree of graft ligamentization, evaluated by measuring the signal-to-noise quotient (SNQ) of the graft. Results: The overall ACL graft rupture rate was 6.0%. The rupture rate was significantly higher in smokers than in nonsmokers (12.8% vs 4.6%, respectively; P = .0498). Smokers also had a significantly higher whole-graft SNQ compared with nonsmokers (4.7 ± 4.4 vs 3.3 ± 3.7, respectively; P = .028), suggesting less satisfactory ligamentization in smokers. Conclusion: Smoking was associated with a higher risk of graft rupture of ACL reconstruction and a higher SNQ of the intact graft as shown on postoperative MRI.

Osteointegration of soft tissue grafts within the bone tunnels in anterior cruciate ligament reconstruction can be enhanced.

Anterior cruciate ligament reconstruction with a soft tissue autograft (hamstring autograft) has grown in popularity in the last 10 years. However, the issues of a relatively long healing time and an inferior histological healing result in terms of Sharpey-like fibers connection in soft tissue grafts are still unsolved. To obtain a promising outcome in the long run, prompt osteointegration of the tendon graft within the bone tunnel is essential. In recent decades, numerous methods have been reported to enhance osteointegration of soft tissue graft in the bone tunnel. In this article, we review the current literature in this research area, mainly focusing on strategies applied to the local bone tunnel environment. Biological strategies such as stem cell and gene transfer technology, as well as the local application of specific growth factors have been reported to yield exciting results. The use of biological bone substitute and physical stimulation also obtained promising results. Artificially engineered tissue has promise as a solution to the problem of donor site morbidity. Despite these encouraging results, the current available evidence is still experimental. Further clinical studies in terms of randomized control trial in the future should be conducted to extrapolate these basic science study findings into clinical practice.

Inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line.

PURPOSE: To assess inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line in a cadaveric model mimicking total knee arthroplasty. METHODS: Four cadaveric knees with intact soft tissues were used. The knees were exposed anteriorly using the Insall approach, with the patella everted laterally. Three observers (2 surgeons and one trainee) took turns to identify the anatomic landmarks of the transepicondylar axis and Whiteside's line. Each observer repeated the process 20 times. Each identification was photographed and referenced with the true values obtained from the knees after they were stripped of all soft tissue. Inter- and intra-observer errors in the anatomic landmarks were compared. RESULTS: Inter-observer error was significant with both the transepicondylar axis and Whiteside's line (p<0.001, one-way ANOVA). The intra-observer variation was greater for Whiteside's line than the transepicondylar axis (standard deviation, 4.2 vs 2.5 degrees). The maximum potential errors in the transepicondylar axis and Whiteside's line were 13 degrees and 24 degrees, respectively. CONCLUSION: The accuracy of rotational alignment of the transepicondylar axis and Whiteside's line were operator-dependent, and their intra-operative reproducibility was low.

Coronal bowing of the femur and tibia in Chinese: its incidence and effects on total knee arthroplasty planning.

PURPOSES: To study the incidence of femoral or tibial bowing in the coronal plane in a Chinese population, and how it affects the accuracy of bone cuts for total knee replacement when an intramedullary alignment system is used. METHODS: Standing radiographs of the entire lower limb of each patient with end-stage primary osteoarthritis of the knee were analysed. All radiographs were digitised and the extent of bowing in the coronal plane measured. A bowing was marked if an angulation was more than 2 degrees. The projected error of cutting was then calculated. RESULTS: Of 93 lower limbs, 58 (62%) of the femurs had marked bowing in the coronal plane; 41 (44%) had a mean lateral bowing of 5.3 (standard deviation [SD], 3.2) degrees; 17 (18%) had a mean medial bowing of 4.4 (SD, 1.9) degrees. Marked tibial bowing in the coronal plane was less common (30 tibias, 32%). If a cutting error of more than 2 degrees was considered unacceptable, significantly more unacceptable cuts would ensue in the groups with marked bowing (p=0.003 for femurs and p<0.001 for tibia, respectively). CONCLUSION: The incidence of femoral or tibial bowing in the coronal plane was high in a Chinese population with end-stage osteoarthritis of the knee. This phenomenon may increase bone cut errors in total knee replacement if an intramedullary alignment system is used and the extent of bowing is not recognised.

Sagittal bowing of the distal femur in Chinese patients who require total knee arthroplasty.

PURPOSES: The importance of the femoral sagittal bowing on total knee arthroplasty is under-recognized. The bowing could lead to potential errors in positioning of the femoral component if it is ignored. We aimed to document the femoral sagittal bowing at different segments of the Chinese femur and to discuss the implications of this sagittal bowing on total knee arthroplasty. METHODS: One hundred lateral radiographs of the entire lower limbs of 85 Chinese patients admitted for total knee arthroplasty were digitized. The radii of curvature of the intramedullary canal of the proximal, middle and distal one-third of the femora were measured. RESULTS: The average age of the patients was 67.3 years. The radii of curvature of the proximal, middle and distal one-third of the femora were 1081.6, 926.2 and 715.1 mm, respectively. The distal one-third of the femora was significantly more bowed than the other parts of the femora (p<0.001). The distal femoral bowing was more profound in rheumatoid patients and in those with a short femur. CONCLUSIONS: The lateral contour of the Chinese femur is like a hockey stick. This exaggerated sagittal bowing in the Chinese femur can affect the final sagittal position of the femoral component and has implications for the choice of implant design. In revision setting, a long and straight press-fit stem might either endanger the anterior cortex or deflect the femoral component to an abnormally extended position.

Strontium exerts dual effects on calcium phosphate cement: Accelerating the degradation and enhancing the osteoconductivity both in vitro and in vivo.

Calcium phosphate cements (CPCs) have long been used as osteoconductive bone substitutes in the treatment of bone defects. However, the degradation rate of CPC is typically too slow to match the new bone growth rate. It is known that strontium increases the solubility of hydroxyapatite as well as exerts both anabolic and anticatabolic effects on bone. Therefore, we hypothesized that the incorporation of strontium would accelerate the degradation rate and enhance the osteoconductivity of CPC. In this study, Three groups, CPC (0% Sr-CPC), 5% Sr-CPC, and 10% Sr-CPC, were prepared, with the total molar ratio for Sr/(Sr+Ca) in the cement powder phase being 0, 5, and 10%, respectively. In the immersion test, less residual weight was observed in both 5% Sr-CPC and 10% Sr-CPC groups than CPC group. In addition, a higher osteoblastic cell proliferation rate and alkaline phosphatase activity were obtained in the strontium groups. In a rat femur bone defect model comparing CPC with 10% Sr-CPC, at 2 weeks postoperation, early endochondral ossification was found in the 10% Sr-CPC group, whereas only fibrous tissue was observed in control group; at 4-16 weeks postoperation, progressive osteoconduction toward the cement was observed in both groups. At 32 weeks, a higher peri-cement bone area and reduced cement area were noted in the 10% Sr-CPC group. In conclusion, in the 10% Sr-CPC group, strontium exerts dual effects on CPC: accelerating degradation rate and enhancing osteoconductivity, as shown here both in vitro and in vivo.