Lateral rim variable angle locked plating versus tension band wiring of simple and complex patella fractures: a biomechanical study.

INTRODUCTION: Treatment of both simple and complex patella fractures is a challenging clinical problem. Although tension band wiring has been the standard of care, it can be associated with high complication rates. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. MATERIALS AND METHODS: Sixteen pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34-C1 or five-part complex AO/OTA 34-C3 patella fractures by means of osteotomies, with each fracture model created in eight pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior (central distal) fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring or a lateral rim variable angle locking plate. Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full extension. Interfragmentary movements were captured via motion tracking. RESULTS: For both fracture types, the articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, lateral rim variable angle locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

A retrospective investigation on clinical and radiographic outcomes of distal tibial fractures after intramedullary nailing using the lateral parapatellar extra-articular approach.

INTRODUCTION: According to reports, the modified extra-articular parapatellar approach allows the performance of tibial nailing in the semi-extended position without the concern of joint violation. However, there remains no special study that has provided a detailed assessment of the benefits and risks of this approach for treating distal tibial fractures (DTFs). The aim of this retrospective study was to investigate the clinical and radiological outcomes of patients with DTFs after intramedullary nailing using a lateral parapatellar extra-articular (LPE) approach in comparison to using the suprapatellar (SP) and transpatellar (TP) approaches. METHODS: Data were collected from 99 patients with a minimum follow-up period of 12 months. Comparisons were conducted between the groups regarding the number of intraoperative fluoroscopies, complications, knee pain, knee range of motion (ROM), the Lysholm Knee Scale (LKS), the Olerud-Molander Ankle Score (OMAS) and radiological findings. RESULTS: The demographic characteristics were comparable between the groups. Fewer intraoperative fluoroscopies were performed in the LPE (27.47 ± 4.98) and SP (26.03 ± 5.12) groups than in the TP group (30.20 ± 7.42; P<0.001). When compared with the other two approaches, the LPE approach was associated with less knee pain (P<0.001) and better knee ROM (P<0.001) at one week postoperative. No significant intergroup differences were detected in the incidence of complications, LKS scores (P = 0.687) and OMAS (P = 0.926). Radiological findings demonstrated that postoperative tibial alignment (P = 0.853), the time of bony union and rate of non-union were similar between the groups. CONCLUSION: The LPE approach can serve as a safe and effective option for tibial nailing, as it offers favourable outcomes in knee pain relief and knee ROM in the early postoperative period and is equivalent to the other two approaches in terms of the incidence of complications, fracture healing, functional recovery and postoperative alignment for patients with DTFs.

Serial Change in Patellar Height after Tension Band Wiring of Patellar Fractures.

Background and Objectives: Patella baja is a common complication after operative treatment for patellar fracture. This study aimed to investigate (1) the serial changes in patellar height and (2) the potential predictive factors for patellar height changes after tension band wiring (TBW) for patellar fractures. Materials and Methods: Forty-one patients who underwent TBW for patellar fracture between March 2019 and September 2022 were enrolled. To identify serial changes in patellar height, modified Blackburne-Peel index (mBPI) was assessed at just after surgery, at 3 months, at 6 months, at 1 year and at the final follow-up. Multiple regression analysis was conducted to identify factors correlated with mBPI difference between the contralateral side (considered as preoperative status) and injured side. Results: The postoperative mBPI exhibited a decline over time (mean mBPI immediately post operation/3 months/6 months/1 year/final follow-up: 0.69/0.63/0.63/0.62/0.61) Specifically, mBPI showed a significant reduction immediately post operation to 3 months (p < 0.001), although comparisons at other time points did not reveal significant differences. A lower position of the fracture was associated with a decrease in patellar height after surgery. Conclusions: Patellar height was mainly decreased from immediately post operation to 3 months. A fracture in a lower position of associated with decreased patellar height after the TBW of the transverse patellar fracture.

Nonmetallic tension band fixation is a viable and low-complication surgical technique in patellar fractures: a five-year retrospective study.

BACKGROUND: Traditionally, patellar fractures (PFs) have been managed using metallic tension band fixation, a method often associated with a notable rate of complications. Considering these challenges, this study explores the potential of nonmetallic fixation as a treatment option for PFs. This research aims to provide robust evidence supporting the use of the nonmetallic tension band fixation technique as an effective alternative to conventional metallic tension band fixation, thereby advancing the standard of care in treating these fractures. METHODS: This retrospective study analyzed a consecutive patient series presenting with PFs from 2008 to 2021, treated with a nonmetallic tension band fixation technique. Inclusion criteria were strictly defined to include individuals over 18 years of age with isolated PFs requiring surgical intervention. The study focused on evaluating postoperative complications and clinical outcomes, as measured by standardized scoring systems, at the final follow-up point to assess the efficacy and safety of the employed surgical technique. RESULTS: In this study, with a mean follow-up of 64 ± 7 months, a total of 64 patients who received open reduction and internal fixation (ORIF) for PFs were enrolled. Among these, five cases required additional surgical interventions. Specifically, two cases were due to knee stiffness, while the remaining three involved complications such as superficial infection, skin irritation, or delayed wound healing. The mean postoperative values recorded for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Oxford knee score (OKS), and visual analog scale (VAS) were 20.4 ± 2.3, 35.5 ± 5.3, and 1.6 ± 0.4, respectively. There were no complications related to the nonmetallic fixation technique or instances of loss of reduction. CONCLUSION: This study substantiates that nonmetallic tension band fixation is a safe and effective alternative to traditional metallic tension band fixation for patellar fractures. The study's low-complication rate and reoperation frequency underscore the value of nonmetallic implants in mitigating adverse effects and enhancing clinical outcomes. LEVEL OF EVIDENCE: IV.

Incidence of postoperative complications in patellar fractures related to different methods of osteosynthesis procedures - a retrospective cohort study.

BACKGROUND: Patellar fractures have a comparatively low incidence compared to all fracture frequencies of the musculoskeletal system. However, surgical management is crucial to prevent postoperative complications that affect the knee joint. The purpose of the present study was to evaluate the incidence of postoperative complications and onset of postoperative osteoarthritis related to the chosen technique of patellar fracture management. METHODS: In a retrospective cohort study consecutive managed, isolated patella fractures were reviewed for demographic data, trauma mechanism, patella fracture type, fixation technique and postoperative complications. The results were documented radiographically and clinically and analysed statistically. The reporting followed the STROBE guidelines. RESULTS: A total of 112 patients were eligible for data evaluation. Surgical management of comminuted patellar fractures with small fragment screws showed significant fewer postoperative complications compared to other fixation techniques (8%, p < 0.043). The incidence of posttraumatic infection was significantly higher following the hybrid fixation technique with cannulated screws and tension wire than following the other analysed techniques (p = 0.024). No postoperative wound infection was observed after screw fixation or locking plate fixation. Symptomatic hardware was most frequently seen after tension-band fixation. Onset of posttraumatic osteoarthritis was most often found after the hybrid fixation technique (55%). CONCLUSION: Surgical management of patellar fractures remains crucial but fracture fixation using plating systems or small fragment screws is least associated with postoperative complications. TRIAL REGISTRATION: Trial registration number (DRKS):00027894.

Combined quadriceps medial patellofemoral ligament reconstruction and osteochondral fixation offers good patient-reported outcomes and low rates of recurrent instability for osteochondral defects secondary to acute patella dislocation.

PURPOSE: Chondral injuries secondary to traumatic patella dislocation are common, and a subgroup of these are significant defects with fragments amenable to fixation. There is a paucity of published evidence assessing patients managed with combined acute patellofemoral stabilisation and osteochondral fixation. The purpose of this study is to report the outcomes of patients with osteochondral injuries secondary to acute traumatic patella dislocation treated with combined early fragment fixation and MPFL reconstruction using a quadriceps tendon turndown technique which has distinct advantages for this cohort, including preventing chondral overloading and non-violation of the patella bone. METHODS: Patients who underwent combined quadriceps tendon MPFL reconstruction and osteochondral fixation were included. Patient demographics, defect characteristics, complications and reoperations were evaluated. Patients were assessed with Lysholm, Kujala, KOOS-PF scores and satisfaction scale at follow up. Pre-operative MRI was assessed for presence of radiological risk factors for patella dislocation and post-operative MRI was used to assess cartilage quality with MOCART 2.0 score. RESULTS: A total of 19 patients (63.2% female) were included. The mean age was 17.4 ± 4.8 years and patients were followed up at a mean 15.8 ± 5.1 months post-surgery. The mean defect size was 2.4 cm2 ± 1.3 cm2, with the most common defect location being the patella (13/19; 68.4%) followed by the lateral femoral condyle (5/19; 26.3%). At final follow up, the overall mean Lysholm, Kujala, and KOOS-PF scores were 84.9 ± 11.1, 89.7 ± 5.8 and 80.6 ± 13.6, respectively. Seventeen patients (89.5%) were satisfied with their outcome. The mean MOCART 2.0 score at final follow-up was 72.5. One patient required medial capsular plication with removal of a loose chondral body and microfracture and 3 knees required minor reoperations. CONCLUSION: Combined acute osteochondral fragment fixation and MPFL reconstruction using a quadriceps tendon graft offers good radiological and patient-reported outcomes with high satisfaction and low rates of recurrent patella dislocation. To our knowledge, this is currently the largest series of its kind in the literature and the results of this study provide a rationale for a combined approach using a quadriceps tendon graft for this cohort. LEVEL OF EVIDENCE: Level IV.

Management of comminuted patellar fractures using suture reduction technique combined with the modified Kirschner-wire tension band.

OBJECTIVES: Surgical management of comminuted patella fractures remains a major challenge for the surgeon. We developed a suture reduction (SR) technique to better preserve the comminuted patella. The study aimed to compare the suture reduction technique with conventional reduction (CR) technique in the management of comminuted patellar fractures using the modified Kirschner-wire (K-wire) tension band. METHODS: From May 2016 to September 2020, a total of 75 patients with comminuted patellar fracture were reviewed retrospectively. Among these cases, 35 patients were in the suture reduction group with a mean age of 52 years, while 40 patients were in the conventional reduction group with a mean age of 53 years. All cases were closed fractures. Comminuted patellar fractures were classified as type 34-C3 according to the AO/OTA classification. Radiographs of the knee were obtained at routine follow-up to evaluate the reduction quality and fracture union. Clinical outcomes including range of motion (ROM), visual analog scale (VAS), Lysholm, and Böstman grading scales were measured at the last follow-up. Postoperative complications were also recorded. RESULTS: The average time from injury to surgery was 5.4 days in suture reduction group and 3.7 days in conventional reduction group (p < 0.05). The surgical time of suture reduction group was less than that of conventional reduction group, but there was no significant difference (p = 0.110) regarding surgical time between the two groups. The average blood loss in suture reduction group was 42.9 ml, while the average blood loss in conventional reduction group was 69.3 ml (p < 0.001). There was no difference regarding fracture union, ROM and knee function score (Lysholm score and Böstman scale) between the two groups. The complication rates were 17.1% in suture reduction group and 12.5% in conventional reduction group respectively (p > 0.05). CONCLUSIONS: In the treatment of comminuted patellar fractures with modified K-wire tension band, the use of suture reduction technique can shorten the surgical time, reduce the surgical trauma, and obtain satisfactory results. This new surgical technique may be particularly effective in management of comminuted patellar fractures when patellectomy would otherwise be considered.

Incidence and concomitant chondral injuries in a consecutive cohort of primary traumatic patellar dislocations examined with sub-acute MRI.

PURPOSE: To present age- and sex-specific cumulative annual incidences of primary traumatic lateral patellar dislocation (LPD) and to detail patient characteristics and concomitant chondral injuries including osteochondral fractures, as visualized on magnetic resonance imaging (MRI), in a large consecutive cohort of knee-injured individuals. METHODS: Data on primary traumatic lateral patellar dislocations were collected from a large consecutive cohort of knee injuries examined with sub-acute MRI in a single centre with a well-defined catchment area. Annual incidences for different age-groups in relation to gender were calculated together with the risk of concomitant chondral and osteochondral injury, during sports and in general. RESULTS: A total of 184 primary patellar dislocations were identified in the cohort of 1145 acute knee injuries (n=175) and surgical records (n=9). Knee MRI was performed within a median of six days of injury. Median age of patients with primary LPD was 16 years (interquartile range, 14-21; range, 9-47) and 41% were females. Males were significantly older than females at the time of injury (median age 17 vs. 15, P = 0.021) and sustained their primary LPD during sports more often than females (65 vs. 40%, P < 0.001). Primary LPD occurred most frequently at the age of 13 to 15 years where the annual incidence was 125 (95% CI, 96-160) per 100,000 persons. The overall annual incidence of primary LPD was 14 (95% CI, 12-16) per 100,000 persons, with a predominance of males versus females (17 vs. 11, P = 0.01). Concomitant lesions to joint surfaces were displayed on MRI or during surgery in 75 (43%) knees. Osteochondral fractures were seen in 32 knees (18%). We found no statistically significant difference in the risk of osteochondral fracture between those injured during sports or during leisure activity (14 vs. 24%, P = 0.08). CONCLUSIONS: The annual incidence of first-time patellar dislocation was found to be 14 per 100,000 individuals with the highest incidence found among those aged 13-15 years. Primary LPD was more common among males and was sustained during sports activity in 55% of the cases. Associated injuries to the chondral surfaces should be expected in 43% of knees with primary LPD where 18% represent osteochondral fractures.

Management of comminuted inferior patellar pole fractures with cerclage-wire-augmented separate vertical wiring: a retrospective clinical study.

PURPOSE: Comminuted inferior patellar pole fractures are challenging injuries and require effective treatment due to the extension mechanism of the knee. This study aims to evaluate the outcome of above fractures treated with a modified technique of cerclage-wire-augmented separate vertical wiring (SVW) with cerclage wiring passed through the proximal patella. METHODS: Retrospective analysis (1/2017-1/2020) were performed for patients that were treated with three SVWs through the posterior margin of proximal fragment and directly to the anterosuperior border of patella, combined with a cerclage wiring passed through the proximal patella. Patients who experienced comminuted inferior patellar pole fractures within 3 weeks were included, and the outcome was evaluated radiologically and clinically by Bostman score after a minimum of 12 months following surgery. Further evaluation included the operation time and complication rate. RESULTS: A total of 20 patients (10 males, 10 females) with a mean age of 54 ± 14.5 years (26-83 years) and a follow-up of 18.9 ± 6.6 months (12-36 months) were evaluated. The average operation time was 45.7 ± 8.8 min (30-60 min). At final follow-up, the average range of motion was 131.3° ± 3.5° (125°-135°), and the mean Bostman score was 29.4 ± 0.7 points (28-30) and graded excellent in all cases. Two patients experienced occasional giving way of the knee. Radiologically no loss of reduction, implant breakage, nonunion or skin irritation was observed. CONCLUSIONS: The cerclage-wire-augmented SVW with cerclage wiring passed through the proximal patella appears to be a safe and simple technique which can effectively treat the comminuted inferior patellar pole fractures.

High Rates of Damage to the Medial Patellofemoral Ligament, Lateral Trochlea, and Patellar Crest After Acute Patellar Dislocation: Magnetic Resonance Imaging Analysis.

PURPOSE: The primary outcome of interest of this study was to determine the frequency, location, and extent of chondral injuries and medial patellofemoral ligament (MPFL) tears, along with the rate of loose bodies, in the knee after acute primary patellar dislocation. The secondary outcome of interest was to conduct a multivariate analysis to investigate whether the presence of pathoanatomic abnormalities, including structural differences in the knees of the patients, is associated with the features of the lesions. METHODS: Patients who underwent magnetic resonance imaging after primary acute patellar dislocation were identified from our institutional databases. We analyzed a total of 175 magnetic resonance imaging scans of patients aged between 14 and 25 years who were eligible for inclusion. RESULTS: Chondral damage to the medial facet of the patella was present in 36 patients; patellar crest, 78 patients; and lateral patellar facet, 28 patients. One patient presented with chondral defects in the medial trochlear facet, whereas 118 patients showed chondral defects in the lateral trochlear facet. Loose bodies were present in 142 patients. A total of 161 patients (92%) showed MPFL damage. The patellar portion was affected in 119 patients. Of the patients, 28 showed a partially damaged MPFL (<50%), 42 showed MPFL damage greater than 50%, and 49 presented with a complete tear of the MPFL. MPFL lesions were observed on the femoral side in 42 patients. Fourteen patients presented with an avulsion fracture on the patellar side; 28 patients, on the femoral side. CONCLUSIONS: The MPFL was injured in 92% of 175 patients after a first-time acute patellar dislocation. Chondral damage was most frequent at the patellar crest, followed by the lateral femoral epicondyle. No association was found between patella alta, the sulcus angle, the Q angle, the tibial tubercle-trochlear groove distance, trochlear and patellar dysplasia, and soft-tissue damage. LEVEL OF EVIDENCE: Level IV, retrospective cohort study.

Treatment of inferior pole fracture of the patella with tension-free external immobilization.

BACKGROUND: Inferior pole fracture of the patella (IPFP) has small and comminuted fracture blocks that are hard to immobilize, and early mobilization may lead to loss of fracture reduction and immobilization failure. Therefore, a difficulty of treatment is to achieve rigid immobilization with early functional exercise. Here, a new treatment method of tension-free external immobilization is put forward. METHODS: The clinical data of 11 IPFP patients treated with tension-free external immobilization from May 2016 to June 2019 were retrospectively analyzed. There were six males and five females aged 39.0 ± 12.8 years (range 18-53 years). IPFP was caused by traffic accidents in five cases and falls in six cases. All cases had unilateral closed injuries, including four in the left knee and seven in the right knee. The preoperative range of motion of the knee was 22.0 ± 7.5° (10-30°). The time from injury to operation was 4.5 ± 1.3 d (3-7 d). The operation-related indices were recorded, and the function of the affected knee was assessed by the Böstman score. RESULTS: All operations were successful. The operation time was 56.4 ± 8.4 mi (45-70 min), the intraoperative blood loss was 54.1 ± 14.6 mL (40-80 mL), and the length of hospital stay was 7.5 ± 1.9 d (5-11 d). The mean follow-up time was 20.4 ± 7.6 months (12-36 months), the duration of fracture healing was 8.9 ± 1.5 weeks (7-12 weeks), and the removal time of the external immobilization device was 10.4 ± 0.9 weeks (9-12 weeks). At the last follow-up, the range of motion had no significant difference between the affected knee (129.7 ± 3.3°, range 125-135°) and the unaffected knee (130.8 ± 3.8°, range 126-137°) (t = 0.718, p < 0.05). The Böstman score of the knee was 29.2 ± 1.0 points (27-30 points), including 10 excellent cases (90.9%) and one good case (9.1%). CONCLUSION: Tension-free external immobilization is a feasible treatment for IPFP. It can help with early functional exercise and achieve a satisfactory clinical effect.

Interventions for treating fractures of the patella in adults.

BACKGROUND: Fractures of the patella (kneecap) account for around 1% of all human fractures. The treatment of these fractures can be surgical or conservative (such as immobilisation with a cast or brace). There are many different surgical and conservative interventions for treating fractures of the patella in adults. This is an update of a Cochrane Review first published in 2015. OBJECTIVES: To assess the effects (benefits and harms) of interventions (surgical and conservative) for treating fractures of the patella in adults. SEARCH METHODS: We searched CENTRAL (2020, Issue 1), MEDLINE, Embase, LILACS, trial registers and references lists of articles to January 2020. SELECTION CRITERIA: We included randomised controlled trials (RCTs) or quasi-RCTs that evaluated any surgical or conservative intervention for treating adults with fractures of the patella. The primary outcomes were patient-rated knee function, knee pain and major adverse outcomes. DATA COLLECTION AND ANALYSIS: At least two review authors independently selected eligible trials, assessed risk of bias and cross-checked data extraction. Where appropriate, we pooled results of comparable trials. MAIN RESULTS: We included 11 small trials involving 564 adults (aged 16 to 76 years) with patella fractures. There were 340 men and 212 women; the gender of 12 participants was not reported. Seven trials were conducted in China and one each in Finland, Mexico, Pakistan and Turkey. All 11 trials compared different surgical interventions for patella fractures. All trials had design flaws, such as lack of assessor blinding, which put them at high risk of bias, potentially limiting the reliability of their findings. No trial reported on health-related quality of life, return to previous activity or cosmetic appearance. The trials tested one of seven comparisons. In the following, we report those of the main outcomes for which evidence was available for the three most important comparisons. Four trials (174 participants) compared percutaneous osteosynthesis versus open surgery. Very low-quality evidence means that we are uncertain of the findings of no clinically important difference between the two interventions in patient-rated knee function at 12 months (1 study, 50 participants) or in knee pain at intermediate-term follow-up at eight weeks to three months. Furthermore, very low-quality evidence means we are uncertain whether, compared with open surgery, percutaneous fixation surgery reduces the incidence of major adverse outcomes, such as loss of reduction and hardware complications, or results in better observer-rated knee function scores. Two trials (112 participants) compared cable pin system (open or percutaneous surgery) versus tension band technique. The very low-quality evidence means we are uncertain of the findings at one year in favour of the cable pin system of slightly better patient-rated knee function, fewer adverse events and slightly better observer-rated measures of knee function. There was very low-quality evidence of little clinically important between-group difference in knee pain at three months. Very low-quality evidence from two small trials (47 participants) means that we are uncertain of the findings of little difference between biodegradable versus metallic implants at two-year follow-up in the numbers of participants with occasional knee pain, incurring adverse events or with reduced knee motion. There was very low-quality and incomplete evidence from single trials for four other comparisons. This means we are uncertain of the results of one trial (28 participants) that compared patellectomy with advancement of vastus medialis obliquus surgery with simple patellectomy; of one quasi-RCT (56 participants) that compared a new intraoperative reduction technique compared with a standard technique; of one quasi-RCT (65 participants) that compared a modified tension band technique versus the conventional AO tension band wiring (TBW) technique; and of one trial (57 participants) that compared adjustable patella claws and absorbable suture versus Kirschner wire tension band. AUTHORS' CONCLUSIONS: There is very limited evidence from nine RCTs and two quasi-RCTs on the relative effects of different surgical interventions for treating fractures of the patella in adults. There is no evidence from trials evaluating the relative effects of surgical versus conservative treatment or different types of conservative interventions. Given the very low-quality evidence, we are uncertain whether methods of percutaneous osteosynthesis give better results than conventional open surgery; whether cable pin system (open or percutaneous surgery) gives better results than the tension band technique; and whether biodegradable implants are better than metallic implants for displaced patellar fractures. Further randomised trials are needed, but, to optimise research effort, these should be preceded by research that aims to identify priority questions.

Fully automated patellofemoral MRI segmentation using holistically nested networks: Implications for evaluating patellofemoral osteoarthritis, pain, injury, pathology, and adolescent development.

PURPOSE: Our clinical understanding of the relationship between 3D bone morphology and knee osteoarthritis, as well as our ability to investigate potential causative factors of osteoarthritis, has been hampered by the time-intensive nature of manually segmenting bone from MR images. Thus, we aim to develop and validate a fully automated deep learning framework for segmenting the patella and distal femur cortex, in both adults and actively growing adolescents. METHODS: Data from 93 subjects, obtained from on institutional review board-approved protocol, formed the study database. 3D sagittal gradient recalled echo and gradient recalled echo with fat saturation images and manual models of the outer cortex were available for 86 femurs and 90 patellae. A deep-learning-based 2D holistically nested network (HNN) architecture was developed to automatically segment the patella and distal femur using both single (sagittal, uniplanar) and 3 cardinal plane (triplanar) methodologies. Errors in the surface-to-surface distances and the Dice coefficient were the primary measures used to quantitatively evaluate segmentation accuracy using a 9-fold cross-validation. RESULTS: Average absolute errors for segmenting both the patella and femur were 0.33 mm. The Dice coefficients were 97% and 94% for the femur and patella. The uniplanar, relative to the triplanar, methodology produced slightly superior segmentation. Neither the presence of active growth plates nor pathology influenced segmentation accuracy. CONCLUSION: The proposed HNN with multi-feature architecture provides a fully automatic technique capable of delineating the often indistinct interfaces between the bone and other joint structures with an accuracy better than nearly all other techniques presented previously, even when active growth plates are present.

Diagnostic accuracy of the Ottawa Knee Rule in adult acute knee injuries: a systematic review and meta-analysis.

OBJECTIVES: This systematic review and meta-analysis aimed to evaluate the current evidence on the diagnostic accuracy of the Ottawa Knee Rule (OKR) for acute knee injuries in adults. METHODS: A literature search of Embase (Elsevier), MEDLINE (U.S. National Library of Medicine), PubMed and Scopus databases (1995 to date; English language) was performed and the relevant references were assessed. Original articles documenting OKR use by emergency physicians to assess adult acute knee injuries were included. Study methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Results of eligible studies were pooled using random effects or fixed effects modelling to calculate the diagnostic performance of the OKR. The Higgins I2 test and Begg's association test were performed to assess between-study heterogeneity and publication bias respectively, with Spearman's correlation test for threshold effect. RESULTS: Eight studies, including 7385 patients, were enrolled and pooled using the random effects model. Sensitivity, specificity, negative likelihood ratio, positive likelihood ratio and diagnostic odds ratio were 0.99 (95% CI, 0.97 to 1.00), 0.49 (95% CI, 0.47 to 0.51), 0.07 (95% CI, 0.02 to 0.24), 1.86 (95% CI, 1.72 to 2.01) and 25.10 (95% CI, 7.18 to 87.70) respectively. Based on the QUADAS-2 criteria, most studies presented low risk of bias and concern regarding applicability. CONCLUSIONS: Application of the OKR can rule out knee fracture and thus avoid unnecessary radiography. These results also translate to improved efficiency, lower medical costs and reduced waiting times. KEY POINTS: • The Ottawa Knee Rule helps clinicians to rule out fracture in adults with an acute knee injury. • The rule allows a reduction in radiography requests, patient waiting time in the emergency department and healthcare costs.

Patellar sleeve avulsion fracture in a patient with Sinding-Larsen-Johansson syndrome: a case report.

BACKGROUND: Patellar sleeve avulsion (PSA) fractures are rare injuries that occur in in skeletally immature patients. Initial diagnosis is key to a successful outcome, as these injuries are easily overlooked on plain radiographs with poor results well documented from delayed management. High index of suspicion from the mechanism of injury, thorough clinical examination and Magnetic Resonance Imaging (MRI) help to avoid misdiagnosis. CASE PRESENTATION: The case of a 12-year-old male athlete with an acute PSA after a conservative treatment of a SLJ syndrome is described. The patient was referred to our clinic due to severe pain and loss of function after performing a high jump. Plain radiographs (X-ray) and MRI confirmed an inferior pole PSA which was fixed with double trans osseous ultra-high strength tapes. At the 3-month follow- up visit the patient was able to ambulate brace free. At 2-years follow up the patient was able to play soccer and ice hockey. To our knowledge, there are no case reports of inferior pole PSA with prior SLJ syndrome described in literature. CONCLUSIONS: Early clinical suspicion and distinguishing this PSA from other enchondral ossification disorders around the knee is critical to avoid misdiagnosis. Whether SLJ syndrome increases the risk of sustaining a PSA is still not clear. Trans osseous fixation with suture tapes leads to good functional results in a young athlete with inferior pole PSA.

The majority of patellar avulsion fractures in first-time acute patellar dislocations included the inferomedial patellar border that was different from the medial patellofemoral ligament attachment.

PURPOSE: Accurate assessment of the locations of patellar avulsion fractures in acute patellar dislocations is clinically relevant for decision making for treatment. The study aim was to classify the locations of patellar avulsion fractures with a focus on the ligament attachments of medial stabilizing structures. METHODS: Out of 131 first-time acute traumatic patellar dislocations, 61 patients had patellar fractures. Subsequently, 10 patients with isolated osteochondral fractures of the articular surface in the patella were excluded. Finally, 51 patients (34 females and 17 males, average age: 18.5 years, 95% CI 16.1-20.9) were included in the study cohort. Based on the locations of the patellar attachment, the patients were divided into three groups: the superior group [medial patellofemoral ligament (MPFL) attachment], inferior group [medial patellotibial ligament (MPTL)/medial patellomeniscal ligament (MPML) attachment], and mixed group. RESULTS: In the patellar avulsion group (51 patients), the superior group, mixed group, and inferior group contained 8/51 (16%), 12/51 (24%), and 31/51 (61%) patients, respectively. CONCLUSIONS: This study showed that 84% of the patellar avulsion fractures were located in the inferomedial patellar border, which consisted of MPTL/MPML attachments that were clearly different from the true "MPFL" attachment at the superomedial patellar border. In terms of the clinical relevance, the acute surgical repair of MPTL/MPML attachments in the inferomedial patellar border may not sufficiently control the patella if optimal management of the MPFL is not performed. LEVEL OF EVIDENCE: IV.

Treatment of posttraumatic patella osteomyelitis with MRSA infection and knee stiffness: a case report.

BACKGROUND: Posttraumatic patella osteomyelitis is rare, and the treatment of osteomyelitis remains to be challenging. Control of the infection commonly costs a long time, and it is easily to cause knee stiffness. In addition, there is no unified protocol for the treatment of knee stiffness. CASE PRESENTATION: We reported a case of posttraumatic patella osteomyelitis that successive infected with methicillin-resistant staphylococcus aureus (MRSA) after multiple surgeries. We successfully treated osteomyelitis by one-staged surgery, but the patient present knee stiffness after treatment. Thus Ilizarov external fixation system was further used to gradually adjust the mobility by exerting mechanical stress to the joint. After adjusting the frame under a scheduled plan, the patient successfully restored satisfactory knee function. CONCLUSIONS: Adequate debridement is the key to control infections of posttraumatic osteomyelitis. Control the infection of posttraumatic patella osteomyelitis by one-staged surgery is achievable and could shorten the knee immobilization period. When knee stiffness occurs, scheduled range of motion (ROM) adjustment using Ilizarov frame with hinges might be a safe and useful method to restore function.

Open tibia plateau fracture with intra-osseous dislocation of the patella and quadriceps tendon rupture: a case report.

BACKGROUND: Both tibial plateau fractures and extensor apparatus injuries are serious injuries to the knee joint that generally do not occur in the same patient. We report a rare case of open tibial plateau fracture combined with quadriceps tendon rupture and complete displacement of the patella into the tibial plateau fracture. CASE PRESENTATION: The case involved a male who was 19 years old who had been in a motorcycle accident. The patient was admitted to our department with an open tibial plateau fracture 3 h post-injury. X-ray showed a tibial plateau fracture and complete displacement of the patella into the tibial plateau. CT showed an avulsion fracture in the patella and tibial intercondylar eminence. Concomitant quadriceps tendon injury and both anterior and posterior cruciate ligament tibial insertion avulsion fractures were considered. The operative findings of emergency surgery confirmed our preoperative diagnosis. Single-stage quadriceps tendon repair and ORIF for the tibial plateau fracture were performed. Satisfactory restoration of function was acquired at the last follow up. CONCLUSION: The most difficult aspect of this case was the determination of the cause of the intra-osseous dislocation of the patella into the tibial plateau. The most likely mechanism of the injury may be that the patient experienced transient posterior dislocation of the knee during the injury. Rupture of the quadriceps tendon should be considered with posterior dislocation of the knee, and the patella was pushed into the tibial plateau fracture by force after the rupture of the quadriceps tendon.

20-year trends of distal femoral, patellar, and proximal tibial fractures: a Danish nationwide cohort study of 60,823 patients.

Background and purpose - Knee fracture treatment burden remains unknown, impeding proper use of hospital resources. We examined 20-year trends in incidence rates (IRs) and patient-, fracture-, and treatment-related characteristics of knee fracture patients.Patients and methods - This nationwide cohort study of prospectively collected data including patients with distal femoral, patellar, and proximal tibial fractures from the Danish National Patient Registry during 1998-2017, assesses IRs of knee fractures (per 105 inhabitants) as well as patient-, fracture-, and treatment-related characteristics of knee fracture patients.Results - During 1998-2017, 60,823 patients (median age 55; 57% female) sustained 74,106 knee fractures. 74% of the study population had a Charlson Comorbidity Index (CCI) of 0 and 18% a CCI of ≥ 2. 51% were proximal tibial fractures, 31% patellar fractures, and 18% distal femoral fractures. At the time of knee fracture, 20% patients had concomitant near-knee fractures (femur/tibia/fibula shaft/hip/ankle), 13% concomitant fractures (pelvic/spine/thorax/upper extremities), 5% osteoporosis, and 4% primary knee osteoarthritis. Over 1/3 knee fractures were surgically treated and of these 86% were open-reduction internal fixations, 9% external fixations, and 5% knee arthroplasties. The most common surgery type was proximal tibia plating (n = 4,868; 60% female). Knee fracture IR increased 12% to 70, females aged > 51 had the highest knee fracture IR, proximal tibial fracture had the highest knee fracture type IR (32) and surgically treated knee fracture IR increased 35% to 23.Interpretation - Knee fracture IRs, especially of surgically treated knee fractures, are increasing and proximal tibial fracture has the highest knee fracture type IR. Females aged > 51 and patients with comorbidity are associated with knee fracture, proximal tibial fracture, proximal tibial fracture surgery, and posttraumatic knee arthroplasty.

Missed Sleeve Fracture of the Superior Pole of Patella.

Patellar sleeve fracture is a form of injury in which small osseous fragments avulsed with periosteum and cartilage. 15-year-old male patient, playing in school football team, apllied to our clinic with a history of previously missed patellar superior pole sleeve avulsion fracture. Care must be taken in order not to miss the patellar superior pole sleeve fractures, which are very rare in children. Extra care must be taken in patients, whose X-ray imaging is clean but there is a problem in the extensor mechanism of the knee. INTRODUCTION Since the patella has high mobility and large cartilage surfaces, it's fracture is very rare in children (9). Growing patella is more prone to osteochondral or avulsion fractures (8). Patellar sleeve fracture is a form of injury in which small osseous fragments fractured with periosteum and cartilage (5). Avulsion or sleeve fractures of patella can be seen in inferior and superior patellar poles. Fractures in superior pole is very rare and only a few cases have been described in the literature (2).