The larger patellar tilt angle and lower intercondylar notch angle might increase posterior cruciate ligament injury risk: a retrospective comparative study.

BACKGROUND: Posterior cruciate ligament (PCL) injuries are common ligament injuries of the knee, and previous studies often focused on the associations between the morphology of the knee and PCL injuries. Studies on the correlation between PCL injuries and patellofemoral alignment are limited. METHODS: This retrospective study included 92 patients with PCL injured and 92 patients with PCL intact. Measurement parameters were compared between the two groups, including patellar tilt angle, congruence angle, patellar height, hip-knee-ankle angle, lateral trochlear inclination, femoral condyle ratio, bicondylar width, intercondylar notch width and index, notch angle, trochlear facet asymmetry, and trochlear sulcus depth and angle. Independent risk factors associated with PCL injuries were identified by logistic regression analyses. RESULTS: In the PCL injured group, the patellar tilt angle was significantly larger (13.19 ± 5.90° vs. 10.02 ± 4.95°, P = 0.04); the intercondylar notch angle was significantly lower (60.97 ± 7.83° vs. 67.01 ± 6.00°, P = 0.004); the medial and lateral femoral condyle ratio were significantly larger (0.63 ± 0.64 vs. 0.60 ± 0.56, P = 0.031; 0.65 ± 0.60 vs. 0.58 ± 0.53, P = 0.005) than in the PCL intact group. There were 11 patients with patellar dislocation in the PCL injured group, accounting for 12%. In these patients, the patellar height was higher (1.39 ± 0.17 vs. 1.09 ± 0.25, P = 0.009); the trochlear sulcus angle was larger (157.70 ± 8.7° vs. 141.80 ± 8.78°, P < 0.001); and the trochlear sulcus depth was shallower (3.10 ± 1.20mm vs. 5.11 ± 1.48mm, P = 0.003) than those in the patients without patellar dislocation. Multivariate analyses showed that patellar tilt angle (each increase 1 degree, OR = 1.14) and intercondylar notch angle (each increase 1 degree, OR = 0.90) were independent risk factors for PCL injuries. CONCLUSION: The patients with PCL injuries had larger patellar tilt angles, lower intercondylar notch angles, and longer posterior femoral condyles than patients with PCL intact. The larger patellar tilt angle and lower intercondylar notch angle might be risk factors for PCL injuries.

Arthroscopy-controlled medial reefing and lateral release for recurrent patellar dislocation: clinical, radiologic outcomes and complications.

BACKGROUND: Few studies have reported the clinical outcomes of the medial reefing procedure and lateral release with arthroscopic control of medial retinacular tension in patients with recurrent patellar dislocation. The purpose of this study was to investigate the clinical, radiologic outcomes and complications of arthroscopy-controlled medial reefing and lateral release. METHODS: Patients who underwent arthroscopy-controlled medial reefing and lateral release for recurrent patellar dislocation between November 2007 and June 2017 were retrospectively evaluated. The clinical outcome (Kujala score), radiologic outcome (congruence and patellar tilt angles), and complications were evaluated at final follow-up. The results were also compared with literature-reported outcomes of other surgical procedures for patellar dislocation. RESULTS: Twenty-five patients (mean age, 18.3 ± 4.8 years) were included in the study. The mean clinical follow-up period was 7.0 ± 2.5 (range, 3.8-12.2) years. The mean Kujala score was significantly improved from 54.7 ± 14.0 (range, 37-86) preoperatively to 91.0 ± 7.6 (range, 63-99) at a mean follow-up period of 7 years (P < 0.001). The radiologic results also significantly improved from 17.8° ± 5.9° to 6.8° ± 2.4° (P < 0.001) in the congruence angle and from 17.5° ± 8.2° to 5.6° ± 3.1° (P < 0.001) in the patella tilt angle at a mean follow-up period of 3.6 years. One patient developed a redislocation after a traumatic event, and two patients showed patellofemoral osteoarthritis progression. CONCLUSIONS: Arthroscopy-controlled medial reefing and lateral release significantly improved the clinical and radiologic outcomes of the patients with recurrent patellar dislocation at a mean follow-up period of 7 years. The results of this study are comparable with the literature-reported outcomes of other surgical procedures for patellar dislocation. LEVEL OF EVIDENCE: Level IV, retrospective therapeutic case series.

Osteoarthritic knees have a highly variable patellofemoral alignment: a systematic review.

PURPOSE: This systematic review aimed to evaluate the variability of patellofemoral (PF) alignment and trochlear morphology in osteoarthritic knees. METHODS: PF alignment of the knee was defined by the following parameters: the sulcus angle (SA), femoral trochlear depth (FTD), patellar tilt angle (PTA), lateral patellofemoral angle (LPFA), lateral femoral trochlear inclination (LFTI) and tibial tubercle-trochlear groove distance (TT-TG). The electronic databases MEDLINE and EMBASE were searched from database inception to the search date (February 19, 2019) and were screened for relevant studies. The PRISMA guidelines were followed. Articles reporting PF alignment measurements of osteoarthritic knees in patients over 40 years old were included. Data were extracted and methodological quality was assessed using a 14-item checklist. RESULTS: A total of 8 studies met the inclusion criteria. The studies reported mean values ± SD between 120° and 141.1° ± 7.7 for the SA; 5.8 mm ± 1.4 for the FTD; between - 0.1° ± 3.3 and 10.3° ± 5.7 for the PTA; between 5.8° ± 5.4 and 17° for the LPFA; between 23.2° ± 5.0 and 27.1° ± 4.4 for the LFTI; and 5.8 mm ± 5.4 for the TT-TG. CONCLUSION: PF alignment in the osteoarthritic knee is more variable than expected. This finding should encourage surgeons to consider the individual preoperative PF alignment more precisely with the aim of reducing anterior knee pain (AKP) after TKA. 3D-CT imaging might be of great value to analyse the PF alignment in an appropriate way. LEVEL OF EVIDENCE: Level III.

Healthy knees have a highly variable patellofemoral alignment: a systematic review.

PURPOSE: There is still lack of knowledge regarding the variability of patellofemoral alignment in healthy, non-osteoarthritic knees, without patellofemoral instability. Therefore, a systematic review of the existing literature was performed to evaluate the variability of patellofemoral alignment. METHODS: Patellofemoral alignment of the knee was defined by the following parameters: sulcus angle (SA), femoral trochlear depth (FTD), patellar tilt angle (PTA), lateral patellofemoral angle (LPFA), lateral femoral trochlear inclination (LFTI) and tibial tubercle-trochlear groove distance (TT-TG). The electronic databases MEDLINE and EMBASE were searched from database inception to search date (January 11, 2019) and screened for relevant studies. The PRISMA guidelines were followed. Articles reporting PF alignment measurements of healthy knees in patients between 15 years and 47 years were included. RESULTS: A total of 15 studies met the inclusion criteria. The studies reported mean values and standard deviations for the SA between 118.7° ± 7 and 168°; for the FTD between 3.4 mm ± 1.1 and 7.1 mm ± 1.8; for the PTA between 0.7° ± 4.99 and 17.05° ± 4.3; for the LPFA between 6.26° ± 4.1 and 11.1° ± 4.0; for the LFTI between 16.3° ± 2.8 and 22.1° ± 1.9; and for the TT-TG between 9.8 mm ± 4.6 and 17.3 mm ± 5.3. CONCLUSION: Patellofemoral alignment in the healthy knee is extremely variable. A more precise knowledge of the complex relationship between the patella and the trochlea may help to better diagnose PF disorders and eventually help in selecting the correct therapy. Furthermore, standardised imaging protocols and measurement techniques for patellofemoral parameters are needed. LEVEL OF EVIDENCE: III.

Noise Generation With Good Range of Motion but Without Femorotibial Instability Has Small Effect on Patient Satisfaction After Total Knee Arthroplasty.

BACKGROUND: There are several causes of patient dissatisfaction after total knee arthroplasty (TKA). This study hypothesized that noise occurring in the knee would worsen patient satisfaction after TKA. METHODS: We mailed a newly developed questionnaire to 103 consecutive participants who were followed for one year, resulting in data from 61 knees in 60 patients (47 women and 13 men, mean age 73 years) who underwent cruciate-substituting TKA. We evaluated postoperative range of motion, knee instability, and the 2011 Knee Society Score in terms of noise generation after TKA. RESULTS: Over half of the patients noticed postoperative noise that occurred during the mid range of knee motion, but noise was not associated with feelings of instability. Postoperative range of motion differed significantly between the group with noise (122.8 ± 12.0°) and that without noise (106.3 ± 23.3°). The patellar tilt angle was also significantly larger in the group with noise (7.4 ± 5.5°) than that without noise (3.3 ± 2.6°). However, collateral ligament laxity had no significant effect on noise, and the 2011 Knee Society Score did not differ significantly different between the noise and no-noise groups. CONCLUSION: Our hypothesis was refuted, and these findings suggest patient satisfaction after TKA is influenced more by good knee function than by noise generation.

Lower extremity rotational deformities and patellofemoral alignment parameters in patients with anterior knee pain.

PURPOSE: Anterior knee pain is a common musculoskeletal condition amongst young adult population. Lower extremity structural factors, such as increased femoral anteversion and lateral tibial torsion, may contribute to patellofemoral malalignment and anterior knee pain. The aim of this study was to evaluate the lower extremity structural factors and related patellofemoral alignment parameters that play a role in the aetiology of anterior knee pain. METHODS: This study involved three groups: patients with unilateral symptomatic knees (n = 35), asymptomatic contralateral knees in the same patients and a control group (n = 40). All subjects were physically examined, and Q-angles were measured. The lower extremities of all subjects were imaged by a very low-dose CT scan, and the symptomatic knees of patients were compared with their asymptomatic contralateral knees and with the healthy knees of controls regarding femoral anteversion, tibial torsion, sulcus angle, patellar tilt angle and lateral patellar displacement. RESULTS: Regarding the Q-angle, femoral anteversion and lateral tibial torsion, no significant differences were found between the symptomatic and asymptomatic knees, whereas significant differences were found between the symptomatic knees and controls. The symptomatic group demonstrated significantly greater sulcus angle only in 30° of knee flexion than did the controls. CONCLUSION: Patients with unilateral anterior knee pain may have similar morphology at their contralateral asymptomatic lower extremity, and different morphology compared with healthy controls. Lower extremity rotational deformities may increase the risk of anterior knee pain; however, these deformities alone are not sufficient to cause knee pain, and may be predisposing factor rather than a direct aetiology. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Upright CT of the knee: the effect of weight-bearing on joint alignment.

OBJECTIVES: To prospectively compare patellofemoral and femorotibial alignment in supine non-weight-bearing computed tomography (NWBCT) and upright weight-bearing CT (WBCT) and assess the differences in joint alignment. METHODS: NWBCT and WBCT images of the knee were obtained in 26 patients (mean age, 57.0 ± 15.9 years; range, 21-81) using multiple detector CT for NWBCT and cone-beam extremity CT for WBCT. Two musculoskeletal radiologists independently quantified joint alignment by measuring femorotibial rotation, tibial tuberosity-trochlear groove distance (TTTG), lateral patellar tilt angle, lateral patellar shift, and medial and lateral femorotibial joint space widths. Significant differences between NWBCT and WBCT were sought using Wilcoxon signed-rank test (P-value < 0.05). RESULTS: Significant differences were found for femorotibial rotation (the NWBCT mean changed from 2.7° ± 5.1 (reader 1)/2.6° ± 5.6 (reader 2) external rotation to WBCT 0.4° ± 7.7/0.2° ± 7.5 internal rotation; P = 0.009/P = 0.004), TTTG (decrease from NWBCT (13.8 mm ± 5.1/13.9 mm ± 3.9) to WBCT (10.5 mm ± 5.0/10.9 mm ± 5.2; P = 0.008/P = 0.002), lateral patellar tilt angle (decrease from NWBCT (15.6° ± 6.7/16.9° ± 7.4) to WBCT (12.5° ± 7.7/15.0° ± 6.2; P = 0.011/P = 0.188). The medial femorotibial joint space decreased from NWBCT (3.9 mm ± 1.4/4.5 mm ± 1.3) to WBCT (2.9 mm ± 2.2/3.5 mm ± 2.2; P = 0.003/P = 0.004). Inter-reader agreement ranged from 0.52-0.97. CONCLUSION: Knee joint alignment changes significantly in the upright weight-bearing position using CT when compared to supine non-weight-bearing CT. KEY POINTS: • Cone-beam extremity CT offers upright weight-bearing examinations of the lower extremities. • Knee alignment changes significantly in an upright position compared to supine position. • Tibial tuberosity-trochlear groove distance (TTTG) is less pronounced in a weight-bearing position. • The weight-bearing position leads to a decrease of the lateral patellar tilt angle.

Correlating quadriceps patellar tendon angle and lateral patellar tilt angle in patients with irregular alignment: a cross-sectional study with retrospective data.

Background: The newly defined angle, quadriceps-patella angle (QPA), reflects the combined force transmitted to the patella by the quadriceps muscles and patellar tendon. An increase in QPA may correlate with an increased force on the patella, which is significant in diagnosing patellofemoral instability and pain syndrome. In our study, we examined how various angles and pathologies vary depending on lateral patellar tilt angle (LPTA). QPA and patellar malalignment was investigated. Thus, the importance of understanding patellar malalignment and the research gap. Methods: Three hundred and fifty patients who underwent knee magnetic resonance imaging (MRI) examinations were included. The cross-sectional study conducted retrospectively between the years of 2018-2020 in a tertiary care outpatient clinic. Shapiro-Wilk normality, Chi-square, Mann-Whitney-U, Spearman correlation and receiver operating characteristic (ROC) curve analysis, statistical tests used for analysis. The patellar tendon length, patellar height, tibial tubercle-trochlear groove distance (TT-TG), patella angle, trochlear sulcus angle, trochlear groove depth (TGD), medial trochlea length (MT), lateral trochlea length (LT), medial trochlear/lateral trochlear length ratio (MT/LT), LPTA, patella-patellar tendon angle (PPTA), QPA, Insall-Salvati index (ISI), medial trochlear inclination (MTI), lateral trochlear inclination (LTI) were among these measurements. In addition, we aim to reveal whether there is a significant relationship between two important angles LPTA and QPA. Whether there is a significant increase in the development of chondromalacia for the patient group with LPTA >5°. We examined how the frequency of chondromalacia changes in the patient group with LPTA >5°. Results: Two hundred and seventy seven patients included in the study and many measurements were performed on MRI. Fad-pad edema was found to be significantly higher in the group with LPTA <5° (P=0.046). TT-TG distance was significantly higher, TGD and MT were significantly lower in patients with higher LPTA (P=0.001, P=0.002 and P=0.017, respectively). A low level of significant positive correlation was found between QPA and patellar tendon length. There is no significant difference between QPA and PPTA angles between the groups with LPTA <5° and >5° (P=0.503, P=0.188). In the ROC analysis performed to determine the cut-off value, the LPTA value ≤14.2° which significantly predicted the presence of fad-pad edema, had the highest sensitivity and specificity [sensitivity: 76.71%, specificity: 39.90%, area under the curve (AUC): 0.588, P=0.024]. Conclusions: QPA is independent from many angles of the knee and does not change significantly. As the patellar tendon length increases, QPA angle also increases. In patients with abnormal LPTA, the frequency of TT-TG distance and chondromalacia increased, while TGD and MT decreased. Patients with a low LPTA can be more carefully examined for chondromalacia and fad-pad edema in clinical and MRI examination.

Effect of different femoral tunnel locations on patellofemoral joint during single-bundle anterior cruciate ligament reconstruction / 中国组织工程研究

BACKGROUND: Studies have shown that arthroscopic single-bundle anterior cruciate ligament reconstruction can restore the forward stability of the knee joint, but the rotational stability of the knee joint and the matching degree with the patellofemoral joint are affected by the central position of the femoral and tibial tunnels. OBJECTIVE: To investigate the relationship between the location of different femoral tunnel centers and patellofemoral articulation and cartilage conditions in young and middle-aged patients with anterior cruciate ligament reconstruction, and to carry out the correlation analysis of patient study factors to further explore the location of the femoral tunnel with the least influence on the patellofemoral joint. METHODS: Seventy patients with anterior cruciate ligament rupture were diagnosed by preoperative MRI, physical examination and intraoperative arthroscopy. All patients were divided into quasi-isometric group and quasi-anatomical group according to the parity of random numbers. In the quasi-isometric group, a Kirschner needle was inserted 7 mm distal to the apex of the lateral wall of the intervertebral fossa using a femoral locator. In the quasi-anatomical group, the Kirschner needle was inserted at the lateral wall of the intercondylar fossa and at the foot print center of the original anterior cruciate ligament. The central coordinates of the femoral tunnel were evaluated on the near-far-front-rear plane based on a standardized grid system, while the central coordinates of the tibial tunnel was evaluated on the anterior-posterior-inner-outer plane, labeled as quadrant Y% and quadrant X%. By comparing the baseline data of patients in the two groups, the difference of lateral patellofemoral angle (LPFA), the difference of cartilage quantitative T2 value, and the correlation between various research factors, the surgical operators were further guided to carry out clinical practice. The implementation of the study protocol complied with the relevant ethical requirements of the First Affiliated Hospital of Anhui Medical University, and all patients signed an informed consent form prior to the participation in the trial. RESULTS AND CONCLUSION: There was no significant difference in baseline data between the two groups, but a significant difference in LPFA existed between the two groups, (0.57±0.33)° in the quasi-anatomical group vs. (1.55±0.36)° in the quasi-isometric group (P<0.001). The T2 values of medial patella, lateral patella and trochlear cartilage in the quasi-anatomical group were all smaller than the corresponding values of the quasi-isometric group. Quadrant X% had a significant negative correlation with LPFA difference (R=-0.664, P<0.01). Quadrant Y% was positively correlated with LPFA difference (R=0.804, P<0.01). The difference of LPFA was significantly positively correlated with T2 values of trochlear and patellar outer cartilage (R=0.651, 0.655, P<0.01). T2 values of trochlea and lateral patella cartilage were negatively correlated with postoperative Lysholm score (R=-0.505, -0.529, P<0.01). Quadrant Y% was highly correlated with T2 value of lateral patella (R=0.825, P<0.01), and significantly correlated with T2 value of trochlear cartilage (R=0.798, P<0.01). Quadrant X% was negatively correlated with T2 values of lateral patella and pulley cartilage (R=-0.639, -0.657, P<0.01). By exploring the change of the patellofemoral joint at early stage after single-bundle anterior cruciate ligament reconstruction, we found that the quasi-anatomical reconstruction relative to the quasi-isometric reconstruction requires less patellofemoral articular cartilage degeneration and smaller patellar tilt angle. Therefore, the surgeon is required to local the center point of the femoral tunnel as far as possible at the quasi-anatomical position, thereby minimizing the degeneration of the patellofemoral joint.

A Study on the Criteria for Lateral Retinacular Release in Total Knee Arthroplasty: The No Thumb Technique with One Stitch Method

PURPOSE: This study was performed to determine new criteria for performing lateral retinacular release (LRR) without having a detrimental effect on patellar tracking. MATERIALS AND METHODS: For 17 patients who underwent bilateral TKAs, LRR was not performed at one side (A) due to improvement of patellar tracking after deflation of tourniquet although maltracking existed with the inflation of tourniquet. At the other side (B), LRR was not performed either because patellar tracking improved with one stich method although maltracking existed regardless of tourniquet status. We measured the lateral patellar tilt angle (LPTA) of each side inthose 17 patients after 1 year after TKAs and compared them. We also surveyed the incidence of LRR in 225 primary TKAs with the staged method of patellar tracking evaluation during the same period. RESULTS: The average LPTA was 3.4degrees at side (A) and 4.6degrees at side (B) respectively. There was no significant difference in LPTA between side (A) and side (B) (p=0.337). From the survey for incidence of LRR in 225 primary TKAs during the same period, LRR was not required in 19% of patients showing good patellar tracking with inflation of tourniquet, 58% of patients showing improved patellar tracking after deflation of tourniquet and 21% of patients showing improved patellar tracking by one stitch method regardless of tourniquet status. Consequently, only 2% of patients required LRR in primary TKA. CONCLUSION: One stitch method under the deflation of tourniquet in evaluating process of patellar tracking during primary TKAs is supposed to be very effective and to reduce the incidence of LRR to only 2% without influencing the LPTA.

A Study of the Decision Status for the Lateral Retinacular Release based on Lateral Patellar Tilt Angle in Total Knee Arthroplasty: Related with Tourniquet Effect

PURPOSE: The pattern of patellar tracking is changed depending upon whether a tourniquet is operating or not. This study was performed to suggest the criteria of lateral retinacular release(LRR) in total knee arthroplasty(TKA) based on the lateral patellar tilt angle(LPTA). MATERIALS AND METHODS: In study 1, the LPTA was compared in 24 bilateral TKAs, one side was required LRR and performed LRR, but not required and not done LRR on the other side according to the patellar tracking status in deflating tourniquet. In the second prospective study, we performed LRR one side and not the other side intentionally in all 11 patients' knees(22 knees) those who were same situations that the patellar tracking was not good under the condition of operating tourniquet but tracking was improved after deflation of tourniquet. We compared LPTA in both studies with paired t-test of SPSS 11.0. RESULTS: The LPTA was average 4.86 degrees on the side of performed LRR and 4.83 degrees on the other side in 24 patients. There was no significant difference of LPTA between them(p=0.952) in study 1. And the LPTA was average 5.18 degrees on the side of underwent LRR based on the condition of operating tourniquet, 5.45 degree on other not LRR side knee. There were also no significant difference between them(p=0.829) in study 2. CONCLUSION: The incidence of LRR will be reduced with no detrimental effect on lateral patellar tilt angle when making decision of LRR based on the patellar tracking status in deflating tourniquet.