Decreased Patellar Fractures and Subluxation With Patellar Component Replacement at Stage-One Spacer.

BACKGROUND: Periprosthetic joint infection is a devastating complication of total knee arthroplasty and is often treated with 2-stage revision. We retrospectively assessed whether replacing the patellar component with articulating stage-one spacers was associated with improved outcomes compared to spacers without patellar component replacement. METHODS: A total of 139 patients from a single academic institution were identified who underwent an articulating stage-one revision total knee arthroplasty and had at least 1-year follow-up. Of the 139 patients, 91 underwent patellar component removal without replacement, while 48 had a patellar component replaced at stage-one revision. Patellar fracture and reinfection at any point after stage-one were recorded. Knee range of motion (ROM), patellar thickness, lateral tilt, and lateral displacement were measured at 6-weeks post stage-one. Chi-square, Fisher's exact, and t-tests were utilized for comparisons. There were no significant demographic differences between groups. RESULTS: Patellar component replacement at stage-one revision was associated with fewer patellar fractures (2.1 versus 12.1%, P = .046), less lateral patellar displacement (1.7 versus 16.0 mm, P < .01), and improved pre to postoperative knee ROM 6 weeks after stage-one (+5.9 versus -11.4°, P = .03). There was no difference in reinfections after stage-2 revision for the replaced or unreplaced patellar groups (15.4 versus 15%, P = 1.000). While the mean time between stage-one and stage-2 was not different (5.2 versus 4.5 months, P = .50), at one-year follow-up, significantly more patients in the patellar component replacement group were satisfied and refused stage-2 revision (45.8 versus 3.3%, P < .001). CONCLUSIONS: Replacing the patellar component at stage-one revision is associated with a decreased rate of patellar fracture and lateral patellar subluxation, improved ROM, and possible increased patient satisfaction, as reflected by nearly half of these patients electing to keep their spacer. There was no difference in reinfection rates between the cohorts.

Fracture of the patella involving inferior pole is associated with postoperative patella baja - A retrospective multicenter study.

BACKGROUND: The patella fracture involving of inferior pole fractures (IPF) may be associated with patella baja, However, the clinical impact of this condition remains unclear. This study aims to clarify 1) the incidence of patella baja following patellar fracture surgery, 2) the associated clinical outcomes with and without the presence of patella baja, and 3) the potential correlation between the detection of IPF on CT and the occurrence of patella baja. METHODS: We conducted a retrospective multicenter study involving 251 patients who underwent surgical treatment for patellar fractures. Patients were divided into the patella baja (PB; n = 49) group and patella norma (PN; n = 202) group. Data collected included demographics, radiographic findings, surgical details, and postoperative complications. We compared these items between PB group and PN group. Logistic regression analyses were used to identify risk factors for patella baja. RESULTS: Immediately following surgery, 36 (14.3%) patients presented with patella baja which increased to 49 cases (19.5%) at six months postoperatively. There is no statistically significant difference in the demographics, surgical details, clinical outcomes and complication between PB group and PN group. While, in the radiographical assessment, the prevalence of IPF on CT scan in the patella baja group was significantly higher than that in the patella norma group. By logistic regression analysis, IPFP on CT was identified as an independent risk factor for patella baja. (odds ratio 2.11, 95% confidence interval: 1.03-4.33, p = 0.042). CONCLUSION: In patients with patellar fractures, the incidence of patella baja increased from 14.3% immediately post-surgery to 19.5% at the six-month check-up. No significant differences were observed in clinical outcomes between the patella baja group and the norma group. The patella fracture involving IPF on CT emerged as a predictive factor for patella baja.

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.

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.

A novel patella fracture fixation technique: finite element analysis.

INTRODUCTION: Patella fractures account for approximately 1% of all bone fractures. The tension band wiring technique has been used in surgical treatment. However, there is no clear information about the location of the K-wires in sagittal plane. Thus, a transverse fracture line was created in the patella finite element model and fixed with Kirchner (k) wires and cerclage at different angles and compared with two different standard tension band models. MATERIALS AND METHODS: A total of 10 finite element models were created to study AO/OTA 34-C1 patella fractures. Two models used the classical tension band method with either circumferential or 8-shaped cerclage wire. The other 8 models used K-wires placed at 45° or 60°, either alone or combination with cerclage wire. A force of 200 N, 400 N, and 800 N were applied at 45° knee angle and the resulting data fracture line opening, surface pressure and stress in the implants were analyzed through finite element analysis. RESULTS: When all the results are considered, it was determined that the K-wires 60° crossing at the fracture line and with cerclage modeling was superior to the other models. The diagonal placement of the K-wires with cerclage (could be 45° or 60° medium) was superior to the reference models. CONCLUSIONS: This study has shown that the new fixation method we propose could come to the fore as an alternative method to be used successfully in transverse patella fractures and lower complications. In transverse patellar fractures, the use of K-wires crossed at 60° may be a good alternative to the standard method.

Do we need to restore patellar thickness after total knee arthroplasty with patellar resurfacing?

PURPOSE: The aim of this study was to investigate whether increased patellar thickness after resurfacing decreased knee flexion angle and had any effect on functional outcomes comparing with patellar thickness restoration (patelloplasty) in patients undergoing primary total knee arthroplasty (TKA) or not. METHODS: We retrospectively reviewed 220 patients undergoing primary TKA: 110 patients undergoing patelloplasty and 110 patients received overstuffed patellar resurfacing using subchondral bone cut at lateral facet technique were recruited. The mean increase in patellar thickness after resurfacing equal to 2 ± 1.2 mm. The outcomes were postoperative knee flexion angle and modified Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score at minimum 2 year after surgery. RESULTS: The mean postoperative knee flexion angles were similar between overstuffed resurfacing group and patelloplasty group (132 ± 7° vs. 134 ± 8°, 95% confidence interval [CI] - 6.9-1.8°, p = 0.1). The mean increase in postoperative knee flexion was 13° in both groups (p = 0.94). The mean change of overall modified WOMAC score was also similar between the two groups (42 ± 12 vs. 39 ± 9 points, 95% CI - 1.7-9.4 points, p = 0.17). CONCLUSION: This study demonstrated that increased patellar thickness has no effect on postoperative knee flexion angle and functional outcomes in TKA. The finding clarified the misunderstanding principle of native patellar thickness restoration after resurfacing which had made many surgeons to refrain from resurfacing especially in patient who had thin patella.

Preoperative incidence and risk factors of deep vein thrombosis in patients with an isolated patellar fracture.

PURPOSE: This study aimed to investigate the incidence, location, and related factors of preoperative deep venous thrombosis (DVT) in patients with isolated patellar fractures. METHODS: Patients with an isolated patellar fracture, admitted between January 2013 and December 2019 at our institution, were retrospectively analyzed. Upon admission, patients underwent routine Doppler ultrasound scanning (DUS) of the bilateral lower extremities to detect DVT; those with DVT were assigned to the case group and those without DVT to the control group. Patients in both groups did not perform preoperative off-bed weight-bearing exercises. Data on demographics, comorbidities, and laboratory test results upon admission were extracted. Variables were evaluated between the two groups using univariate analyses, and independent risk factors associated with DVT were identified by logistic regression analysis. RESULTS: During the study period, 827 patients were included, of whom 5.8% (48/827) were found to have preoperative DVT. In DVT patients, 85.4%(41/48) were injured, 8.3%(4/48) were not injured, and 6.3%(3/48) were lower limbs. Multivariate analysis showed that male (male vs. female, odds ratio, OR = 2.25), delayed from injury to DUS (in each day, OR = 1.29), and elevated plasma D-dimer level (> 0.5 µg/mL, OR = 2.47) were independent risk factors associated with DVT. CONCLUSIONS: Despite the low prevalence of DVT after an isolated patellar fracture, this study underscores the importance of identifying those with a high risk of DVT, especially those with multiple identifiable factors, and encourage the early targeted use of anti-thromboembolic agents to reduce DVT occurrence.

Transpatellar bone tunnels perforating the lateral or anterior cortex increase the risk of patellar fracture in MPFL reconstruction: a finite element analysis and survey of the International Patellofemoral Study Group.

PURPOSE: (1) To determine applied patellar drilling techniques for medial patellofemoral ligament (MPFL) reconstruction among members of the International Patellofemoral Study Group (IPSG) and (2) to evaluate the risk of patellar fracture for various patellar bone tunnel locations based on a finite element analysis (FEA) model. METHODS: In the first part of the study, an online survey on current MPFL reconstruction techniques was conducted among members of the IPSG. In the second part of the study, a three-dimensional FEA model of a healthy knee joint was created using a computed tomography scan. Patient-specific bone density was integrated into the patella, and cartilage of 3 mm thickness was modeled for the patellofemoral joint. According to the survey's results, two different types of patellar bone tunnels (bone socket and transpatellar bone tunnel) were simulated. The risk of patellar fracture was evaluated based on the fracture risk volume (FRV) obtained from the FEA. RESULTS: Finite element analysis revealed that subchondral bone socket tunnel placement is associated with the lowest FRV but increased with an anterior offset (1-5 mm). Transpatellar bone tunnels violating the lateral or anterior cortex showed a higher FRV compared to bone socket, with the highest values observed when the anterior cortex was penetrated. CONCLUSION: Violation of the anterior or lateral patellar cortex using transpatellar bone tunnels increased FRV compared to a subchondral patellar bone socket tunnel. In MPFL reconstruction, subchondral patellar bone socket tunnels should be considered for patellar graft fixation to avoid the risk of postoperative patellar fracture. LEVEL OF EVIDENCE: Survey; Descriptive laboratory study/Level V.

Plate osteosynthesis in patellar fractures: a systematic review and meta-analysis.

INTRODUCTION: To perform a systematic review and assess the indications, outcomes, complications, and union rates associated with plate osteosynthesis in patellar fractures compared to tension band wiring. METHODS: The systematic search was conducted for articles in PubMed, Embase Biomedical, Cochrane central, and LILACS databases (date of inception to July 30, 2020). Articles were included if they were randomized control trials, cohort studies, case-control studies, and case series (with more than five cases), which focused on the clinical outcomes of patients with plate osteosynthesis as a treatment for fracture of the patella and had a minimum follow-up of 3 months. All studies were assessed according to their level of evidence, the number of patients, age of patients, fracture patterns described, complications of treatment, and results summarized. Meta-analysis could only be done for two parameters (complications and reoperations) due to the paucity of data and heterogeneity of studies' limited statistical analysis. The data are presented as a review table with the key points summarized. RESULTS: Twenty studies (seven prospective and 13 retrospective articles) identified 533 patients with 534 fractures who had undergone plate osteosynthesis for fracture of the patella. The most common fracture treated with plate osteosynthesis was 34C. CONCLUSION: Basket plate was most commonly used for inferior pole fractures, while mesh plates were for intra-articular patella fractures. Overall plating was associated with better clinical outcomes, fewer complication rates, and high union rates compared to tension band wiring for patella fractures.

[Postoperative outcomes in patients with closed patellar fractures]. / Rezul'taty operativnogo lecheniya zakrytogo pereloma nadkolennika.

OBJECTIVE: To improve postoperative outcomes in patients with closed patellar fractures using a new method of surgical treatment. MATERIAL AND METHODS: The authors proposed a new method of patellar osteosynthesis. Technique of osteosynthesis is described, and surgical scheme is presented. Treatment outcomes were analyzed in 68 patients with closed patellar fractures. The control group consisted of 34 patients who underwent Weber osteosynthesis. The authors assessed clinical and radiological data. Moreover, clinical example of a patient with traumatic closed patellar fracture and illustrations of surgical treatment are presented. RESULTS: Clinical data indicate the advantage of treatment in the main group.

Patellar Fracture After Total Knee Arthroplasty With Retention: A Retrospective Analysis of 2954 Consecutive Cases.

BACKGROUND: To the best of our knowledge, there have been no large case studies on patellar fracture after total knee arthroplasty (TKA) with patella retention. METHODS: From 2005 to 2019, 2954 consecutive TKAs with patella retention were retrospectively reviewed. The incidence of patellar fracture was confirmed. Perioperative demographic factors associated with patellar fracture were compared between the nonpatellar fracture control (randomly selected after age and sex matching) and patellar fracture patient groups. To confirm the prognosis of identified patellar fractures, Hospital for Special Surgery knee score, union rates, and complications after treatment were evaluated. Treatment outcomes were compared as per the treatment method, and fracture type was classified by shape. RESULTS: For primary TKAs with patella retention, patellar fracture occurred in 32 of 2883 cases (incidence 1.11%). When comparing the preoperative demographic factors between the patellar fracture and control groups, there was a significant difference in knee flexion of the affected limb. Twenty-three cases were treated nonoperatively, and nine cases were treated operatively. Of the 32 patellar fractures, 28 had confirmed union, and the HSS score at the latest follow-up increased significantly from the preoperative score. The only complication noted after treatment was nonunion in three cases. We found no significant differences in treatment results as per the treatment method and fracture type. CONCLUSION: Patellar fracture after TKA with retained patella is infrequent, with relatively improved clinicoradiological results over those of patellar fracture after TKA with resurfaced patella reported in the literature. The improved results did not differ as per the treatment method and fracture type.

Initial conservative treatment of osteochondral fracture of the patella following first-time patellar dislocation.

BACKGROUND: There has been no gold standard of the initial treatment strategy for acute patellar dislocation (APD) with osteochondral fracture (OCF). Hence the study aim is firstly, to review and compare clinical outcomes of patients who underwent conservative treatment for APD with or without OCF. Secondly, to characterize the location and size of fracture fragment. METHODS: Sixty-nine consecutive patients who were retrospectively evaluated after first-time APD over a 2- year period were divided into two groups (group 1 (n = 24): APD with OCF and group 2 (n = 45): APD only). Magnetic resonance imaging (MRI) was used to assess patients with APD and OCF from the medial patella. All patients were treated with a supervised course of immobilization followed by progressive range of motion and strength exercise protocol. History of a recurrent dislocation, radiologic and functional scores were analyzed. RESULTS: Redislocation rate was 31.2% in group 1 and 26.6% in group 2, showing no significant difference between the two groups (p = 0.690). Intergroup differences in terms of final Kujala and IKDC scores were not significant (p = 0.117 and p = 0.283, respectively). Fracture sites of the patella in group 1 were classified as follows: patellar medial margin (12), inferomedial facet (7), and inferomedial facet involving central ridge (5). In the subgroup of patient with OCF of the inferomedial facet of the patella, the fragments were found in the lateral gutter and did not cause pain or mechanical symptoms. Thus, loose body removal was not performed. However, all five patients with large OCF involving the central ridge of the patella failed non-operative treatment with recurrent dislocations, ultimately requiring fragment refixation and medial retinacular imbrication. CONCLUSIONS: First, APD patients with OCFs of medial margin or inferomedial facet showed similar redislocation rates and functional knee scores with those without OCFs after conservative treatment. Second, initial conservative treatment failed in some APD patients with large OCF, especially when OCFs were fractured from inferomedial facet involving central ridge. Surgery should be considered with this type.

Role of an additional third screw in the fixation of transverse patellar fracture with two parallel cannulated screw and anterior wire.

BACKGROUND: Two parallel cannulated screws along with an anterior wire to construct a tension band is a popular approach in transverse patellar fractures. However, the optimal screw proximity, either deep or superficial screw placements, remains controversial. Hence, a new concept of the addition of a third screw to form a triangular configuration along with the original two parallel screws was proposed in this study. Therefore, the biomechanical effect of the additional third screw on the stability of the fractured patella was investigated with finite element (FE) simulation. METHODS: An FE knee model including the distal femur, proximal tibia, and fractured patella (type AT/OTA 34-C) was developed in this study. Four different screw configurations, including two parallel cannulated screws with superficial (5-mm proximity) and deep (10-mm proximity) placements and two parallel superficial screws plus a third deep screw, and two parallel deep screws plus a third superficial screw, with or without the anterior wire, were considered for the simulation. RESULTS: Results indicated that the addition of a third screw increased stability by reducing the dorsal gap opening when two parallel screws were deeply placed, particularly on the fractured patella without an anterior wire. However, the third screw was of little value when two parallel screws were superficially placed. In the existence of two deep parallel screws and the anterior wire, the third screw reduced the gap opening by 23.5% (from 1.15 mm to 0.88 mm) and 53.6% (from 1.21 mm to 0.61 mm) in knee flexion 45° and full extension, respectively. Furthermore, in the absence of the anterior wire, the third screw reduced the gap opening by 73.5% (from 2 mm to 0.53 mm) and 72.2% (from 1.33 mm to 0.37 mm) in knee flexion 45° and full extension, respectively. CONCLUSION: Based on the results, a third cannulated screw superficially placed (5-mm proximity) is recommended to increase stability and maintain contact of the fractured patella, fixed with two parallel cannulated screws deeply placed (10-mm proximity), particularly when an anterior wire was not used. Furthermore, the third screw deeply placed is not recommended in a fractured patella with two parallel superficial screws.

Roles of the screw types, proximity and anterior band wiring in the surgical fixation of transverse patellar fractures: a finite element investigation.

BACKGROUND: Cannulated screws with an anterior wire are currently used for managing transverse patellar fracture. However, the addition of anterior wiring with various types of screws via open surgery to increase the mechanical stability is yet to be determined. Hence, this study aimed to compare the mechanical behaviors of a fractured patella fixed with various screws types and at various screw locations with and without the anterior wire. The present study hypothesized that using the anterior wire reduces the fracture gap formation. METHODS: A finite element (FE) model containing a fractured patella fixed with various types of cannulated screws and anterior wiring was created in this study. Three types of screws, namely partial thread, full thread, and headless compression screws, and two screw depths, namely 5 and 10 mm away from the anterior surface of the patella, were included. The effect of the anterior wire was clarified by comparing the results of surgical fixation with and without the wire. Two magnitudes and two loading directions were used to simulate and examine the mechanical responses of the fractured patella with various fixation conditions during knee flexion/extension. RESULTS: Compared with partial thread and headless compression screws, the full thread screw increased the stability of the fractured patella by reducing fragment displacement, fracture gap formation, and contact pressure while increasing the contact area at the fracture site. Under 400-N in the direction 45°, the full thread screw with 5-mm placement reduced the gap formation by 86.7% (from 2.71 to 0.36 mm) and 55.6% (from 0. 81 to 0. 36 mm) compared with the partial thread screw with 10-mm placement, respectively without and with the anterior wire. CONCLUSION: The anterior wire along with the full thread screw is preferentially recommended for maintaining the surgical fixation of the fractured patella. Without the use of anterior wiring, the full thread screw with 5-mm placement may be considered as a less invasive alternative; however, simple screw fixation at a deeper placement (10 mm) is least recommended for the fixation of transverse patellar fracture.

Five-pointed star lattice sutures for fixation of patella transverse fractures: a clinical study.

INTRODUCTION: Fixation of displaced patella fractures with metal implants may be associated with implant failure, post-operative pain, and high re-operation rate. This study reports preliminary clinical results of using five-pointed star lattice sutures for the management of patella transverse fractures. METHODS: A five-pointed star lattice suture configuration was produced intraoperatively, and 25 patients with patella transverse fractures were treated with this newly designed sutures fixation. All patients were followed up until union of the fractures or until further surgical intervention. At a mean of 1.6 years (range 0.8-2.5 years) of follow-up, the notes and plain radiographs of the 25 patients were reviewed. Bostman score was used to evaluate the therapeutic effects. RESULTS: All 25 patients experienced union of the patella fractures, with excellent knee function in 19 patients and good in 6 patients evaluated with Bostman score. CONCLUSION: The newly designed five-pointed star lattice sutures fixation may be a feasible alternative to metal implants fixation in the management of patella transverse fracture. LEVEL OF EVIDENCE: Level IV case series.

Patellar complications following total knee arthroplasty: a review of the current literature.

Total knee arthroplasty is a common operation for treating patients with end-stage knee osteoarthritis and generally has a good outcome. There are several complications that may necessitate revision of the implants. Patella-related complications are difficult to treat, and their consequences impact the longevity of the implanted joint and functional outcomes. In this review, we explore the current literature on patellar complications in total knee arthroplasty and identify risk factors as well as strategies that can help in preventing these complications. We present pertinent findings relating to patellar complications. They can be classified into bony or soft tissue complications and include bone loss, aseptic loosening, periprosthetic fractures, patella fracture, patellar clunk syndrome, patellofemoral instability, extensor mechanism complications, maltracking, patella baja and malrotation. We conclude that patellar complications in total knee arthroplasty are common and have significant implications for the functional outcome of total knee arthroplasty. A high index of suspicion should be maintained in order to avoid them. Implant malpositioning and other forms of intraoperative technical error are the main cause of these complications, and therefore, primary prevention is crucial. When dealing with these established problems, a clear plan of action should be formulated in advance to allow appropriate management as well as anticipation of adverse outcomes.

Intra-operative patellar fracture during chronic patellar tendon rupture reconstruction: salvage and prophylactic modified techniques.

Management of chronic neglected patellar tendon rupture represents a challenging condition for the orthopedic surgeons to deal with due to many factors such as quadriceps muscle atrophy, superior migration of the patella, e.g., patella alta, peri-patellar adhesions and patellar tendon atrophy. Such difficulties might be further complicated by intra-operative patellar fracture during patellar tendon reconstruction. In the current article, the authors report (1) a salvage procedure for such devastating intra-operative complication, based on bypassing the patella and gaining the advantage of the quadriceps tendon for structural and functional restoration of the knee extensor mechanism, and (2) prophylactically a technical modification of patellar tendon reconstruction guarding against such inadvertent patellar fracture.

Increased Patellar Fracture Rate in Total Knee Arthroplasty With Preoperative Varus Greater Than 15°: A Case-Control Study.

BACKGROUND: Management of severe varus deformity requires soft tissue balancing for implantation of low-constraint knee prosthesis. Patellar complications have been rarely studied in this specific group. Our hypothesis was that severe genu varum (>15°) would increase the rate of patellar complications. METHODS: Using a prospective cohort of 4216 prostheses performed at a single center beginning in 1987, we analyzed 280 prostheses having preoperative varus greater than 15°, compared to 673 total knee arthroplasties (TKAs) with a preoperative hip-knee-ankle angle of 180° ± 2°. Preoperative and postoperative clinical and radiological characteristics were compared between the 2 groups, with particular attention paid to patellar complications. RESULTS: Average follow-up was 40.2 months (24-239). The mean preoperative Knee Society Score (KSS) was statistically higher in the normal (hip-knee-ankle angle 180° ± 2) axis group (62.65 vs 37.47, P = .001). At the last follow-up, no significant difference was found between the 2 groups in terms of postoperative KSS (87.5 in the varus group vs 87.3 in the normal axis group, P = .87). The rate of satisfied patients was identical between the 2 groups (85.3% vs 88.8%, P = .49). However, at mid-term, there were more patellar fractures in the varus group (2.9% vs 0.9%, P = .005). A significantly lower patellar height in both the varus group and the group of patella fractures (P < .001) was also found. CONCLUSION: TKA in severe varus knees produces a KSS equivalent to TKA in knees with a mechanical axis of 0 ± 2. The risk of patellar fracture could initiate a decline in patella resurfacing in patients with major varus deformation, especially in case of a preoperative patella baja.

Comminuted inferior pole fracture of patella can be successfully treated with rim-plate-augmented separate vertical wiring.

INTRODUCTION: We present the surgical technique of rim-plate-augmented separate vertical wiring for comminuted inferior pole fracture of the patella and report the clinical outcomes. MATERIALS AND METHODS: Between July 2013 and January 2016, 13 patients (7 male and 6 female) who were diagnosed with comminuted inferior pole fracture of the patella in preoperative computed tomography and underwent a minimum of 1 year of follow-up were enrolled in this study. Mean patient age was 57.7 years (range 28-72 years). All patients underwent open reduction and internal fixation by rim-plate-augmented separate vertical wiring. Bony union, complications, range of motion and Bostman score were the clinical outcomes. RESULTS: Bony union was achieved in all cases at an average of 10 weeks after surgery (range 8-12). There was no loss of reduction and fixative failure during follow-up. The average range of motion was 127° (range 120°-130°). The mean Bostman score at last follow-up was 29.6 points (range 27-30) and graded excellent in 12 patients. CONCLUSION: Rim-plate-augmented separate vertical wiring demonstrated secure fixation and favorable clinical outcomes. This study provides evidence for its effectiveness as a fixation method for treating displaced, comminuted inferior pole fracture of the patella.