Introduction. In my paediatric Orthopaedic practice I use Kirchner wires for the fixation of the TSF on bone. I noted a significant percentage of wire loosening during the post-operative period. The aim of this project was to establish the effectiveness of the wire clamping mechanism and find ways to reduce the incidence of wire loosening when using the TSF. Materials and Methods. In the first instance wire slippage was measured intra-operatively after the tensioner was removed using an intra-operative professional camera. Following this study mechanical tests were performed in the lab measuring the pull out properties of Kirchner wires using different bolts and different torque levels in order to tighten the wire on the fixator. Results. Our clinical study confirmed wire slippage intra-operatively immediately after the tensioner was removed. Wire slippage after the tensioner was removed was found to vary from 0.01 mm to 0.51 mm (mean 0.19 mm). Our mechanical tests showed that the ideal torque for tightening the wire on the frame using a bolt was around 15 N.m. A comparison between cannulated and slotted bolts suggested that cannulated bolts are more effective as a clamping mechanism. A comparison between aluminium made Taylor Spatial frame rings and stainless steel made Ilizarov rings suggested that the Taylor Spatial frame rings are more effective as part of a clamping mechanism. Conclusions. It is important that clinicians routinely measure the torque they use to clamp wires on circular external fixators. Clinicians and manufacturers are informed that the type of bolt used is important in maintaining wire tension. Manufacturers should design the ideal bolt which effectively grips the wire without the risk of fracture. The Ilizarov frame clamping mechanism can be effectively used with the Taylor Spatial frame

Chronic extensor mechanism insufficiency around TKA is a very challenging pathology to treat. An insufficient extensor mechanism negatively affects implant survival and patient outcomes. There are several risk factors for extensor mechanism disruption and the surgeon should be aware and avoid these problems in the perioperative period. In appropriately selected patients, reconstruction of the extensor mechanism is a valid option. Whole extensor mechanism and Achilles tendon allograft reconstruction of the deficient extensor mechanism have been proposed with good early published results. These reconstructions, however, are expensive and with time may stretch and lead to recurrence of an extensor lag. An alternative to allograft, is the use of Marlex mesh as popularised by Browne and Hanssen. This technique uses a knitted monofilament polypropylene mesh that is secured to the patient's native lateral tissue and covered by an appropriately dissected and distalised vastus medialis muscle. The technique can be used for both patellar and quadriceps tendon deficiencies and can be done with or without implant revision and is currently the treatment of choice at the presenter's institution. The surgeon should be aware of the complexity and limitations of these three reconstructive techniques

Extensor mechanism complications after or during total knee arthroplasty are problematic. The prevalence ranges from 1–12% in TKR patients. Treatment results for these problems are inferior to the results of similar problems in non-TKR patients. Furthermore, the treatment algorithm is fundamentally different from that of non-TKR patients. The surgeon's first question does not focus on primary fixation; rather the surgeon must ask if the patient needs surgery and if so am I prepared to augment the repair? Quadriceps tendon rupture, periprosthetic patellar fracture, and patellar tendon rupture have similar treatment algorithms. Patients who are able to perform a straight leg raise and have less than a 20-degree extensor lag are generally treated non-operatively with extension bracing. The remaining patients will need surgical reconstruction of the extensor mechanism. Loose patellar components are removed. Primary repair alone is associated with poor results. Whole extensor mechanism allograft, Achilles tendon allograft, and synthetic mesh reconstruction are the current techniques for augmentation. In the acute setting if these are not available hamstring tendon harvest and augmentation is an option. Achilles tendons and synthetic mesh are easier to obtain than and entire extensor mechanism but are limited to patients that have an intact patella and the patella that can be mobilised to within 2–3 cm of the joint line. No matter which technique is used the principles are: rigid distal/tubercle fixation, coverage of allograft/mesh with host tissue to decrease infection, tensioning the augment material in extension, no flexion testing of reconstruction and post-operative extension bracing

Extensor mechanism complications after or during total knee arthroplasty (TKA) are problematic. The prevalence ranges from 1%-12% in TKA patients. Treatment results for these problems are inferior to the results of similar problems in non-TKA patients. Furthermore, the treatment algorithm is fundamentally different from that of non-TKA patients. The surgeon's first question does not focus on primary fixation; rather the surgeon must ask if the patient needs surgery and if so am I prepared to augment the repair? Quadriceps tendon rupture, peri-prosthetic patellar fracture, and patellar tendon rupture have similar treatment algorithms. Patients who are able to perform a straight leg raise and have less than a 20-degree extensor lag are generally treated non-operatively with extension bracing. The remaining patients will need surgical reconstruction of the extensor mechanism. Loose patellar components are removed. Primary repair alone is associated with poor results. Whole extensor mechanism allograft, Achilles tendon allograft, and synthetic mesh reconstruction are the current techniques for augmentation. In the acute setting if these are not available, hamstring tendon harvest and augmentation is an option. Achilles tendons and synthetic mesh are easier to obtain than an entire extensor mechanism but are limited to patients that have an intact patella and the patella that can be mobilised to within 2–3 cm of the joint line. No matter which technique is used the principles are: rigid distal/tubercle fixation, coverage of allograft/mesh with host tissue to decrease infection, tensioning the augment material in extension, no flexion testing of reconstruction and post-operative extension bracing

A key component to the success of total knee replacement is the health and integrity of the extensor mechanism. While there are issues related to the patella, such as fracture, dislocation, subluxation, clunk due to peripatellar fibrosis and anterior knee pain, the overall integrity of the extensor mechanism is of tantamount importance in providing an excellent functional outcome. During total knee replacement it is of utmost importance to preserve the anatomic insertion of the patellar tendon on the tibial tubercle. However, after total knee replacement, a fall or extreme osteoporosis of the patella may cause a rupture of the patellar tendon, distally or proximally, and possibly the quadriceps tendon off of the proximal pole of the patella. Simple repairs of the patellar tendon avulsion may involve use of the semitendonosis and gracilis tendons along with primary repair of the tendon. Usually, patella infera develops after such a repair affecting overall strength and function. For severe disruptions of the extensor mechanism that are accompanied by a significant extensor lag, autologous tissue repair may not be possible. Thus, there are three techniques for reconstruction of this difficult problem: Extensor mechanism allograft with bone-patellar tendon-patella-quadriceps tendon, extensor mechanism allograft with os calcis-Achilles tendon construct and Marlex-mesh reconstruction for patellar tendon avulsion. The key to success of extensor mechanism allograft is proper tensioning of the allograft at full extensor and immobilisation for 6 weeks. Rosenberg's early experience showed that the allograft works best placed at maximum tension in extension. Rubash has described the use of the os calcis-Achilles tendon which does not utilise a patellar substitute. Hansen has recently described excellent results with the use of Marlex mesh to act as a structural reinforcement to the patellar tendon when it is avulsed

A key component to the success of total knee replacement is the health and integrity of the extensor mechanism. While there are issues related to the patella, such as fracture, dislocation, subluxation, clunk due to peripatellar fibrosis and anterior knee pain, the overall integrity of the extensor mechanism is of tantamount importance in providing an excellent functional outcome. During total knee replacement it is of utmost importance to preserve the anatomic insertion of the patellar tendon on the tibial tubercle. However, after total knee replacement, a fall or extreme osteoporosis of the patella may cause a rupture of the patellar tendon, distally or proximally, and possibly the quadriceps tendon off of the proximal pole of the patella. Simple repairs of the patellar tendon avulsion may involve use of the semitendonosis and gracilis tendons along with primary repair of the tendon. Usually, patella infera develops after such a repair affecting overall strength and function. For severe disruptions of the extensor mechanism that are accompanied by a significant extensor lag, autologous tissue repair may not be possible. Thus, there are three techniques for reconstruction of this difficult problem: Extensor mechanism allograft with bone-patellar tendon-patella-quadriceps tendon, extensor mechanism allograft with os calcis-Achilles tendon construct and Marlex-mesh reconstruction for patellar tendon avulsion. The key to success of extensor mechanism allograft is proper tensioning of the allograft at full extensor and immobilisation for 6 weeks. Rosenberg's early experience showed that the allograft works best placed at maximum tension in extension. Rubash has described the use of the os calsis-Achilles tendon which does not utilise a patellar substitute. Hansen has recently described excellent results with the use of Marlex mesh to act as a structural reinforcement to the patellar tendon when it is avulsed

General Principles. All repairs should be repaired in full extension. Repairs should be immobilised in full extension for 6–12 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees. Marlex mesh has been shown to be an excellent replacement as well as an augment for deficient soft tissue. Acute tibial tuberosity avulsion. Open repair is best accomplished with a non-absorbable heavy Krackow suture, secured distally around a screw and washer followed by 6 to 8 weeks of immobilization. Augmentation with a semitendinosus graft or Marlex mesh can provide additional support. Acute Patella Tendon Rupture. End-to-end repair is standard, but re-rupture is not uncommon, so supplemental semitendinosus reconstruction is recommended. The tendon is harvested proximally, left attached distally and passed through a transverse hole in the inferior patella. The gracilis tendon can be harvested and sutured to semitendinosus for additional length, if needed. Acute Quadriceps Tendon Rupture. These can be repaired end-to-end with a non-absorbable heavy Krackow suture. A superficial quadriceps fascial turndown or mesh may be a useful adjunct. Patella Fracture. Treatment depends on the status of the patellar component and the loss of active extension. If the component remains well fixed and the patient has less than a 20-degree lag, non-operative treatment in extension. A loose component and/or > 20-degree extensor lag requires ORIF +/− component revision. Chronic Disruptions. While standard repair techniques are possible, tissue retraction usually prevents a “tension-free” repair. If the patella remains viable and has not retracted proximally an Achilles tendon graft is appropriate. In chronic disruptions with loss of the patella, allograft extensor mechanism reconstruction may be considered. Marlex mesh repair has also been shown to be effective in reconstruction of chronic patellar and quadriceps tendon defects

Extensor mechanism disruption in total knee arthroplasty (TKA) occurs infrequently but often requires surgical intervention. We compared two cohorts undergoing extensor mechanism allograft reconstruction, one group had an extensor mechanism rupture, and the other had a recurrent ankylosed knee. Thirteen consecutive patients with extensor mechanism disruption or ankylosis after TKA were treated. Two different types of extensor mechanism allografts were used: quadriceps tendon-patella-patella tendon-tibial tubercle, and Achilles tendon allograft(Fig1). Demographic factors, diagnosis at extensor failure, Knee Society clinical rating scores, radiographs, and patient satisfaction were recorded. The average time from extensor mechanism disruption to surgery was 6.6 months (range, 1-24 months). At a mean followup of 24 months (range, 6-46 months), all patients were community ambulators. None of the patients showed a postoperative extensor lag. Average postoperative maximum flexion was 97° (90-115°) for the ruptured group and 80° (75-90) for the ankylosed grup. All patients thought their functional status had improved, and 87% were satisfied with the results of the allograft reconstruction (Fig 2, 3, 4, 5). One patient had allograft failure due to recurrent infection after re-revision for sepsis. The total extensor mechanism allograft and Achilles tendon allograft both were successful in the treatment of the failed extensor mechanism and showed promising results for the treatment of the ankylosed knee

General Principles: All repairs should be repaired in full extension. Repairs should be immobilised in full extension for 6–12 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees. Marlex Mesh has been shown to be an excellent replacement as well as an augment for deficient soft tissue. Acute tibial tuberosity avulsion: Open repair is best accomplished with a non-absorbable heavy Krackow suture, secured distally around a screw and washer followed by 6 to 8 weeks of immobilization. Augmentation with a semitendinosus graft or Marlex can provide additional support. Acute Patella Tendon Rupture: End-to-end repair is standard, but re-rupture is not uncommon, so supplemental semitendinosus reconstruction is recommended. The tendon is harvested proximally, left attached distally and passed through a transverse hole in the inferior patella. The gracilis tendon can be harvested and sutured to semitendinosus for additional length, if needed. Acute Quadriceps Tendon Rupture: These can be repaired end-to-end with a non-absorbable heavy Krackow suture. A superficial quadriceps fascial turndown or mesh may be a useful adjunct. Patella Fracture: Treatment depends on the status of the patellar component and the loss of active extension. If the component remains well fixed and the patient has less than a 20-degree lag, non-operative treatment in extension. A loose component and/or > 20-degree extensor lag requires ORIF +/− component revision. Chronic Disruptions: While standard repair techniques are possible, tissue retraction usually prevents a “tension-free” repair. If the patella remains viable and has not retracted proximally an Achilles tendon graft is appropriate. In chronic disruptions with loss of the patella, allograft extensor mechanism reconstruction may be considered. Marlex mesh repair has also been shown to be effective in reconstruction of chronic patellar and quadriceps tendon defects

Supracondylar fractures of the humerus (SCH) are one of the most common orthopaedic injuries in childhood. Numerous studies worldwide demonstrate that play equipment is a common mechanism of injury for SCH. Our study aimed to identify the prevalence of play equipment related SCH in a large population in Western Sydney. We conducted a retrospective analysis of 856 infants who suffered a SCH between 2001–2007 and were treated at The Children's Hospital at Westmead. We obtained data on patient demographics, mechanism of injury, severity of SCH (Gartland classification), and management of SCH (open reduction vs closed reduction vs. non operative management). Of the total 856 patients, 739 provided useful information for analysis. In 696 of these patients the mechanism of injury could be determined according to the patients information provided in the medical record. The mechanisms of injury were as follows: trampoline 72 (10.3%), monkey bars 58 (8.3%), slides 26 (3.7%), other playground equipment 84 (12.0%), home furniture 157 (22.6%), bikes 39 (5.6%), non-equipment related fall 260 (37.3%). Of the patient demographics, there was a significant correlation between the age groups (0–3, 4–7, 8+ years) and severity of SCH (Ï24 = 18.36, p=0.001). Fifty-two percent of Gartland type three fractures occurred in the age group of 4–7 years. The study demonstrates that playground equipment represents a major mechanism of injury of SCH in children. In particular trampoline related SCH and to a lesser degree monkey bar related SCH, represent an area in which primary preventative strategies should be targeted

Purpose. Previous retrieval studies demonstrate increased tibial baseplate roughness leads to higher polyethylene backside wear in total knee arthroplasty (TKA). Micromotion between the polyethylene backside and baseplate is affected by the locking mechanism design and can further increase backside wear. This study's purpose was to examine modern locking mechanisms influence, in the setting of both polished and non-polished tibial baseplates, on backside tibial polyethylene damage and wear. Methods. Five TKA models were selected with different tibial baseplate and/or locking mechanism designs. Six retrieval tibial polyethylenes from each TKA model were matched based on time in vivo (TIV), age at TKA revision, BMI, gender, number of times revised, and revision reason. Two observers visually assessed each polyethylene. Primary outcomes were visual damage scores, individual visual damage modes, and linear wear rates determined on micro-computed tomography (micro-CT) scan in mm/year. Demographics were compared by one-way ANOVA. Damage scores, damage modes, and linear wear were analyzed by the Kruskal-Wallis test and Dunn's multiple comparisons test. Results. There were no differences among the groups based on TIV (p=0.962), age (p=0.609), BMI (p=0.951), gender, revision number, or reason for revision. There was a significant difference across groups for visual total damage score (p=0.031). The polished tibial design with a partial peripheral capture locking mechanism and anterior constraint demonstrated a significantly lower score compared to one of the non-polished tibial designs with a complete peripheral-rim locking mechanism (13.0 vs. 22.0, p=0.019). Otherwise, mean total damage scores were not significant between groups. There were identifiable differences among the groups based on abrasions (p=0.006). The polished design with a tongue-in-groove locking mechanism demonstrated a significantly higher score compared to one of the designs with a non-polished baseplate (5.83 vs. 0.83, p=0.016). Only the two designs with non-polished baseplates demonstrated dimpling (5.67 and 8.67), which was significant when compared against all other groups (p<0.0001), but not against each other (p>0.99). No other significant differences were identified when examining burnishing, cold flow, scratching, or pitting. No polyethylene components exhibited embedded debris or delamination. There was a significant difference among groups for linear wear on micro-CT scanning (p=0.003). Two of the polished baseplate designs, one with the partial peripheral rim capture and one with the tongue-in-groove locking mechanism, demonstrated significantly lower wear rates than the non-polished design with a complete peripheral-rim locking mechanism (p=0.008 and p=0.032, respectively). There were no other differences in wear rates between groups. Conclusions. Total damage scores and wear rates were similar between all groups except when comparing two of the polished TKA designs to one of the non-polished baseplate designs. The other TKA model with a non-polished tibial baseplate had similar damage scores and wear rates to the polished designs, likely due to its updated locking mechanism. Dimpling was specific for non-polished tibial baseplates while abrasions were identified in the design with a tongue-in-groove locking mechanism. Our study showed even in the setting of a non-polished tibial baseplate, modern locking mechanisms can decrease backside damage and wear similar to that of other current generation TKA designs. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Previous retrieval studies demonstrate increased tibial baseplate roughness leads to higher polyethylene backside wear in total knee arthroplasty (TKA). Micromotion between the polyethylene backside and tibial baseplate is affected by the locking mechanism design and can further increase backside wear. The purpose of this study was to examine modern locking mechanisms, in the setting of both roughened and polished tibial baseplates, on backside tibial polyethylene wear. Five TKA models were selected, all with different tibial baseplate and/or locking mechanism designs. Six retrieval tibial polyethylenes from each TKA model were matched based on time in vivo (TIV), age at TKA revision, BMI, gender, number of times revised, and revision reason. Two observers scored each polyethylene backside according to a visual damage score and individual damage modes. Primary outcomes were mean damage score and individual damage modes. Demographics were compared by one-way ANOVA. Damage scores and modes were analysed by the Kruskal-Wallis test and Dunn's multiple comparisons test. There were no differences among the groups based on TIV (p=0.962), age (p=0.651), BMI (p=0.951), gender, revision number, or reason for revision. There was a significant difference across groups for mean total damage score (p=0.029). The polished tibial design with a partial peripheral capture locking mechanism and anterior constraint demonstrated a significantly lower score compared to one of the roughened tibial designs with a complete peripheral-rim locking mechanism (13.0 vs. 22.1, p=0.018). Otherwise, mean total damage scores were not significant between groups. As far as modes of wear, there were identifiable differences among the groups based on abrasions (p=0.005). The polished design with a tongue-in-groove locking mechanism demonstrated a significantly higher score compared to both groups with roughened tibial baseplates (5.83 vs. 0.83, p=0.024 and 5.83 vs. 0.92, p=0.033). Only the two designs with roughened tibial baseplates demonstrated dimpling (5.67 and 8.67) which was significant when compared against all other groups (p0.99). No other significant differences were identified when examining burnishing, cold flow, scratching, or pitting. No polyethylene components exhibited embedded debris or delamination. Total damage scores were similar between all groups except when comparing one of the polished TKA design to one of the roughened designs. The other TKA model with a roughened tibial baseplate had similar damage scores to the polished designs, likely due to its updated locking mechanism. Dimpling wear patterns were specific for roughened tibial baseplates while abrasive wear patterns were identified in the design with a tongue-in-groove locking mechanism. Our study showed even in the setting of a roughened tibial baseplate, modern locking mechanisms decrease backside wear similar to that of other current generation TKA designs

General Principles - All repairs should be repaired in full extension. Repairs should be immobilised in full extension for 6–12 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees. Marlex Mesh has been shown to be an excellent replacement as well as an augment for deficient soft tissue. Acute Tibial Tuberosity Avulsion - Open repair is best accomplished with a non-absorbable heavy Krackow suture, secured distally around a screw and washer followed by 6 to 8 weeks of immobilisation. Augmentation with a semitendinosus graft or Marlex can provide additional support. Acute Patella Tendon Rupture - End-to-end repair is standard, but re-rupture is not uncommon, so supplemental semitendinosus reconstruction is recommended. The tendon is harvested proximally, left attached distally and passed through a transverse hole in the inferior patella. The gracilis tendon can be harvested and sutured to semitendinosus for additional length, if needed. Acute Quadriceps Tendon Rupture - These can be repaired end to end with a non-absorbable heavy Krackow suture. A superficial quadriceps fascial turndown or mesh may be a useful adjunct. Patella Fracture - Treatment depends on the status of the patellar component and the loss of active extension. If the component remains well fixed and the patient has less than a 20-degree lag. A loose component and/or >20-degree extensor lag requires ORIF +/− component revision. Chronic Disruptions - While standard repair techniques are possible, tissue retraction usually prevent a “tension-free” repair. If the patella remains viable and has not retracted proximally an Achilles tendon graft is appropriate while in any patellar tendon defect, mesh repair has been shown to be effective. In most chronic disruptions with loss of the patella allograft extensor mechanism reconstruction may be considered

General Principles. All repairs should be repaired in full extension. Repairs should be immobilised in full extension for 6–12 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees. Marlex Mesh has been shown to be an excellent replacement as well as an augment for deficient soft tissue. Acute tibial tuberosity avulsion. Open repair is best accomplished with a non-absorbable heavy Krackow suture, secured distally around a screw and washer followed by 6–8 weeks of immobilization. Augmentation with a semitendinosus graft or Marlex can provide additional support. Acute Patella Tendon Rupture. End to end repair is standard, but re-rupture is not uncommon, so supplemental semitendinosus reconstruction is recommended. The tendon is harvested proximally, left attached distally and passed through a transverse hole in the inferior patella. The gracilis tendon can be harvested and sutured to semitendinosus for additional length, if needed. Acute Quadriceps Tendon Rupture. These can be repaired end to end with a non-absorbable heavy Krackow suture. A superficial quadriceps fascial turndown or mesh may be a useful adjunct. Patella Fracture. Treatment depends on the status of the patellar component and the loss of active extension. If the component remains well fixed and the patient has less than a 20-degree lag. A loose component and/or >20-degree extensor lag requires ORIF +/− component revision. Chronic Disruptions. While standard repair techniques are possible, tissue retraction usually prevents a “tension-free” repair. In most chronic disruptions allograft extensor mechanism reconstruction is preferable. If the patella remains viable and has not retracted proximally, an Achilles tendon graft is appropriate while in any patellar tendon defect, mesh repair has been shown to be effective

High-energy injuries involving the proximal tibia sometimes result in significant soft tissue injuries that may create an incompetent knee extensor mechanism. Reconstruction of the extensor mechanism using the gastrocnemii has been previously described in those patients with tissue loss following either arthroplasty or tumour surgery. In 2009, a single cross-sectional study of eight patients described the technique after trauma, and their outcome at an average of 24 months. Use of a gastrocnemius rotational myoplasty has been described in the literature for six additional cases following trauma. We present our indications, technique and 5-year results of a separate series of four patients in whom the extensor mechanism of the knee was rendered incompetent after direct tissue loss, or subsequent infection, secondary to trauma. In each case, after stabilisation of the periarticular fracture and control of infection, the medial gastrocnemius was employed both to reconstruct the patellar ligament, and to simultaneously restore soft tissue coverage. Three out of 4 patients had excellent outcomes, have returned to their previous occupations and participate in regular sport. The overall mean scores were: Oxford knee Score (38.25), Knee Injury and Osteoarthritis Outcome Score (KOOS) (64.5) and Modified Cincinnati Score (68.25). Mean knee ROM was 5–97 degrees. Video for basic gait analysis was recorded. For those traumatic injuries with the difficult combination of a soft tissue deficit and incompetence of the knee extensor mechanism, we believe the medial gastrocnemius rotational myoplasty provides an excellent reconstructive option to address both of these fundamental problems simultaneously

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described for complete disruption of the extensor mechanism, the results in patients with a prior TKA are inferior to those in patients without a TKA, and frequently have required the use of allograft tendon grafts which can attenuate and stretch over time. However, encouraging results have been reported by Browne and Hanssen in treatment of patellar tendon disruption with the use of a synthetic mesh (knitted monofilament polypropylene). In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with non-absorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the soft tissues lateral patellar tendon remnants to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised and brought in a pants-over-vest manner over the mesh graft, and secured with additional sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of <10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function. A similar modified method has been used at our institution for chronic quadriceps tendon disruptions as well. The reconstructions have shown less of a tendency to late attenuation, stretch and recurrent extensor lag beyond two years compared to our experience with tendon allograft reconstructions and remains our procedure of choice at our institution for the majority of these challenging problems

Introduction. Backside wear of polyethylene (PE) inlays in fixed-bearing total knee replacement (TKR) generates high number of wear debris, but is poorly studied in modern plants with improved locking mechanisms. Aim of study. Retrieval analysis of PE inlays from contemporary fixed bearing TKRs - to evaluate the relationship between backside wear and liner locking mechanism and material type and roughness of the tibial tray. Methods. MATERIAL. We included five types of implants, revised after min. 12 months (14–71): three models with a peripheral locking rim and two models with a dove-tail locking mechanism. Altogether this study included 15 inlays were removed from TKRs with CoCr alloy tray with a roughened surface and a peripheral locking lip liner (Stryker Triathlon, Ra 5,61 µm), 9 from CoCr trays with peripheral locking lip and untreated surface (Aesculap Search, Ra 0,81 µm), 13 from Ti alloy trays with peripheral locking lip and untreated surface (DePuy PFC Sigma 0,61 µm), 11 from Ti alloy trays with untreated surface and dovetail locking mechanism (Zimmer NexGen, 0,34 µm), and 9 from iplants with a Ti alloy tibial tray with mirror polished surface and dovetail locking mechanism (Smitn&Nephew Genesis II, 0,11 µm). METHODS. Wear of bearing surface and back side of retrieved inlays was examined in 10 sectors under a light microscope. Seven modes of wear were analysed and quantified according to the Hood scale: surface deformation, pitting, embedded third bodies, pitting, scratching, burnishing (polishing), abrasion and delamination. Damage of inlays caused by backside wear was also evaluated using scanning electron microscopy (SEM). Roughness of tibial tray was evaluated using a contact profilometer. Results. We found no differences between wear scores on the articulating surface in all group, they did not correlate with backside wear scores in all groups as well. Compared to all other groups, backside wear scores were significantly higher in implants with untreated Ti alloy tibial tray (P<0,001 Wilcoxon test). Lowest wear rates were found in implants from both Ti and CoCr alloys and peripheral locking rim. Interestingly there was no difference between wear of implants with polished and untreated surface (Fig. 1). SEM analysis demonstrated different wear modes in implants with dovetail mechanism and peripheral rim. The first group demonstrated signs of gross rotational instability, with severe abrasion with an arch-shaped pattern and delaminated PE (Fig 2). In one design we observed severe extrusion of PE into screw holes of the tibial tray. Inlays from trays with peripheral rim presented two types of wear: flattening of machining marks or protrusion of the material caused by the rough surface (Fig 3). Conclusions. This study demonstrates that backside wear is still a problem in modern TKR. Our findings suggest that it is predominantly affected by type of locking mechanism (with peripheral rim performing better), to a lesser extent by surface roughness of the tibial component, while material type does not seem to play an important role. This study was funded by a grant from the National Science Centre nr 2012/05/D/NZ5/01840. To view tables/figures, please contact authors directly

General Principles: All repairs should be repaired in full extension. Repairs should be immobilised in full extension for 6–12 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees. Marlex Mesh has been shown to be an excellent replacement as well as an augment for deficient soft tissue. Acute tibial tuberosity avulsion: Open repair is best accomplished with a non-absorbable heavy Krackow suture, secured distally around a screw and washer followed by 6–8 weeks of immobilization. Augmentation with a semitendinosus graft or Marlex can provide additional support. Acute Patella Tendon Rupture: End-to-end repair is standard, but re-rupture is not uncommon, so supplemental semitendinosus reconstruction is recommended. The tendon is harvested proximally, left attached distally and passed through a transverse hole in the inferior patella. The gracilis tendon can be harvested and sutured to semitendinosus for additional length if needed. Acute Quadriceps Tendon Rupture: These can be repaired end-to-end with a non-absorbable heavy Krackow suture. A superficial quadriceps fascial turndown or mesh may be a useful adjunct. Patella Fracture: Treatment depends on the status of the patellar component and the loss of active extension. If the component remains well fixed and the patient has less than a 20 degree lag. A loose component and/or > 20 degree extensor lag requires ORIF +/− component revision. Chronic Disruptions: While standard repair techniques are possible, tissue retraction usually prevents a “tension-free” repair. In most chronic disruptions allograft extensor mechanism reconstruction is preferable. If the patella remains viable and has not retracted proximally an Achilles tendon graft is appropriate while in any patellar tendon defect, mesh repair has been shown to be effective

Objective:. Accurate measurement of the extension and flexion gap is important in total knee arthroplasty (TKA). Particularly, the flexion gap may be influenced by several factors; therefore, tension of the posterior cruciate ligament (PCL), knee extensor mechanism, and the thigh weight may need to be considered while estimating the flexion gap. However, there is no comprehensive study on the flexion gap, including an assessment of the influence of gravity on the gap. The purpose of this study is to investigate the influence of PCL, knee extensor mechanism, and thigh weight on the flexion gap by using a fresh frozen cadaver. Methods:. A fresh frozen lower limb that included the pelvis was used for the assessments. The knee was resected by a measured resection technique and a femoral component was implanted to estimate the component gap. The knee was flexed by precisely 90 degrees using a computer navigation system. The flexion gap was measured in different situations: group A, PCL preserved and patella reduced; group B, PCL preserved and patella everted; group C, PCL resected and patella reduced; and group D, PCL resected and patella everted. In each group, the measurements were obtained under 3 different conditions: 1, knee flexed and the lower limb on the operation table under gravity, as is usually done in TKA; 2, hip and knee flexed 90 degrees to avoid the influence of gravity; and 3, knee set in the same position as in condition 1 and the thigh was held by hand to reduce the influence of the thigh weight. Results:. The flexion gap differed according to groups and conditions. Group B was larger than group A in most conditions and group D was larger than group C. The flexion gap in group D was the largest among the 4 groups. The extensor mechanism had influences to the flexion gap (Table 1). In groups A and B, the flexion gaps were similar under conditions 1, 2, and 3; however, in groups C and D, the flexion gaps in condition 1 were smaller than those in conditions 2 and 3. The thigh weight condition had influences to the flexion gap when the PCL was resected (Table 2). Conclusion:. This is the first systemic report about the influences of PCL, extensor mechanism, and thigh weight on flexion gap measurement in TKA. PCL, extensor mechanism, and thigh weight influence the flexion gap and should be considered during TKA surgery. Especially, careful consideration is necessary to estimate the flexion gap when the PCL is resected and the patella is everted because the flexion gap becomes much wider than other situations

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described, the results in patients with a prior TKA are inferior to those in patients without a TKA. However, optimistic results have been reported by Browne and Hanssen with the use of a synthetic mesh (knitted monofilament polypropylene)3. In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with nonabsorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the lateral soft tissues to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised in a pants-over-vest manner over the mesh graft, and secured with sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of > 10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function