Fatigue performance of angle-stable tibial nail interlocking screws

Purpose

Tibial nail interlocking screw failure often occurs during delayed fracture consolidation or at early weight bearing of nailed unstable fractures, in general when high implant stress could not be reduced by other means. Is there a biomechanical improvement in long-term performance of angle stable locking screws compared to conventional locking screws for distal locking of intramedullary tibial nails?

Methods

Surrogate bones of human tibiae were cut in the distal third and distal locking of the 10 mm intramedullary tibial nail was performed with either two angle stable locking screws or two conventional locking screws in the mediolateral plane. Six specimens per group were mechanically tested under quasi-static and cyclic axial loading with constantly increasing force.

Results

Angle stable locking screw constructs exhibited significantly higher stiffness values (7,809 N/mm ± 647, mean ± SD) than conventional locking screw constructs (6,614 N/mm ± 859, p = 0.025). Angle stable locking screw constructs provided a longer fatigue life, expressed in a significantly higher number of cycles to failure (187,200 ± 18,100) compared to conventional locking screw constructs (128,700 ± 7,000, p = 0.004).

Conclusion

Fatigue performance of locking screws can be ameliorated by the use of angle stable locking screws, being especially important if the nail acts as load carrier and an improved stability during fracture healing is needed.     

Management of fractures of the distal third tibia by minimally invasive plate osteosynthesis – A prospective series of 50 patients

Background

Minimally invasive plate osteosynthesis (MIPO) is an established technique for fixation of fractures of the distal third tibia. Our study aimed to manage intra articular and extraarticular fractures of the distal third tibia by the minimally invasive plate osteosynthesis technique and follow them prospectively. Clinical and radiological outcomes were studied and clinical indications & efficacy of the procedure reviewed. Though many studies on the subject have been done previously, these have been retrospective reviews or small series.

Methods

From May 2010 to May 2013, 50 patients of closed distal tibial fractures were operated by MIPO technique with a distal tibial anatomical locking plate having 4.5/5 proximal and 3.5/4 distal screw holes. The follow up duration was for 3 years.

Results

The mean fracture healing time was 21.4 weeks (range 16–32 weeks) and average AOFAS score 95.06 was out of a total possible 100 points. At last follow up, superficial infection occurred in 5 patients (10%); deep infection, implant failure and malunion in 1-patient each (2%).

Conclusion

MIPO technique provides good, though slightly delayed bone healing and decreases incidence of nonunion and need for bone grafting. This technique should be used in distal tibia fractures where locked nailing cannot be done like fractures with small distal metaphyseal fragments, vertical splits, markedly comminuted fractures and in fractures with intra-articular extension.     

Fibular fixation as an adjuvant to tibial intramedullary nailing in the treatment of combined distal third tibia and fibula fractures: a biomechanical investigation

Objective

Distal third tibia fractures have classically been treated with standard plating, but intramedullary (IM) nailing has gained popularity. Owing to the lack of interference fit of the nail in the metaphyseal bone of the distal tibia, it may be beneficial to add rigid plating of the fibula to augment the overall stability of fracture fixation in this area. This study sought to assess the biomechanical effect of adding a fibular plate to standard IM nailing in the treatment of distal third tibia and fibula fractures.

Methods

Eight cadaveric tibia specimens were used. Tibial fixation consisted of a solid titanium nail locked with 3 screws distally and 2 proximally, and fibular fixation consisted of a 3.5 mm low-contact dynamic compression plate. A section of tibia and fibula was removed. Testing was accomplished with an MTS machine. Each leg was tested 3 times; with and without a fibular plate and with a repetition of the initial test condition. Vertical displacements were tested with an axial load up to 500 N, and angular rotation was tested with torques up to 5 N•m.

Results

The difference in axial rotation was the only statistically significant finding (p = 0.003), with fibular fixation resulting in 1.1° less rotation through the osteotomy site (17.96° v. 19.10°). Over 35% of this rotational displacement occurred at the nail–locking bolt interface with the application of small torsional forces.

Conclusion

Fibular plating in addition to tibial IM fixation of distal third tibia and fibula fractures leads to slightly increased resistance to torsional forces. This small improvement may not be clinically relevant.     

Tibia Vara Affects the Aspect Ratio of Tibial Resected Surface in Female Japanese Patients Undergoing TKA

Background

Tibia vara seen in Japanese patients reportedly influences the tibial component alignment when performing TKA. However, it is unclear whether tibia vara affects the component position and size selection.

Questions/purposes

We therefore determined (1) the amount of medial tibial bow, (2) whether the tibia vara influences the aspect ratio of the tibial resected surface in aligning the tibial component with the tibial shaft axis, and (3) whether currently available tibial components fit the shapes of resected proximal tibias in terms of aspect ratio.

Methods

We measured the tibia vara angle (TVA), proximal varus angle (PVA), and the mediolateral and middle AP dimensions of the resected surface using three-dimensional preoperative planning software in 90 knees of 74 female patients with varus osteoarthritis. We determined the correlations of the aspect ratio with TVA or PVA and compared the aspect ratios to those of five prosthesis designs.

Results

The mean TVA and PVA were 0.6° and 2.0°, respectively. The aspect ratio negatively correlated with both TVA and PVA (r = −0.53 and −0.55, respectively). The mean aspect ratio of the resected surface was 1.48 but gradually decreased with increasing AP dimension, whereas four of the five prostheses had a constant aspect ratio.

Conclusions

The aspect ratio of resected tibial surface was inversely correlated to the degree of tibia vara, and currently available prosthesis designs do not fit well to the resected surface in terms of aspect ratio.

Clinical Relevance

The design of a tibial component with a smaller aspect ratio could be developed to obtain better bone coverage in Japanese patients.     

A biomechanical comparison of the Surgical Implant Generation Network (SIGN) tibial nail with the standard hollow nail

Objective

In developing countries, tibial shaft fractures are frequently stabilised using Surgical Implant Generation Network (SIGN) nails. Despite widespread use throughout the world, little is known regarding their biomechanical properties. This study aimed to compare the mechanical stiffness of the SIGN tibial nail with a standard hollow tibial nail.

Methods

A fracture gap model was created to simulate a comminuted mid-shaft tibia fracture (AO/OTA42-C3) using synthetic composite bones. The constructs were stabilised with either a 9 mm solid SIGN nail or a 10 mm hollow Russell-Taylor nail. Both nail systems were interlocked proximally and distally. Following fixation, the specimens were loaded in axial, torsional, and cyclical axial modes to calculate construct stiffness and irreversible (plastic) deformation.

Results

The mean axial stiffness for the SIGN nail constructs was 47% higher than mean stiffness for the RT nail constructs (p < 0.001). The difference in torsional stiffness was not statistically significant. However, the SIGN group demonstrated 159% more irreversible deformation than the Russell-Taylor group (p = 0.006) for the loading parameters studied.

Conclusion

The SIGN tibial nail, despite its slightly smaller diameter, can provide similar construct stiffness and stability, when compared to a larger hollow nail for stabilisation of tibial shaft fractures.     

Intramedullary fixation of forearm fractures with new locked nail

Background:

Lack of availability of interlocked nails made plate osteosynthesis the first choice of treatment of forearm fractures inspite of more surgical exposure, periosteal stripping and big skin incision subsequent scar along with higher risk of refracture on implant removal. We hereby report the first 12 cases with 19 forearm bone fractures internally fixed by indegenous interlocked nail.

Materials and Methods:

Existing square nails were modified to have a broad proximal end of 5.5 mm with a hole for locking screw of 2.5 mm. The nail has a distal hole of 1/1.2/1.5 mm in 2.5/3/3.5 mm diameter nail, respectively. A new method of distal locking with a clip made of k wire is designed. The clip after insertion into the bone and hole in nail and opposite cortex snuggly fits the bone providing a secure locking system. Twelve skeletally mature patients, mean age 32 years (range 24-45 years) with 19 diaphyseal fractures of the forearm were treated with this indigenously made new nail. The patient were evaluated for fracture union, functional recovery and complications. The functional outcome was assessed by disabilities of arm, shoulder and hand questionnaire (DASH score).

Results:

Time to radiographic union ranged between 12 and 28 weeks, with a 100% union rate. Complications were minimal, with mild infection in open fracture (n=1) and delayed union (n=1) in patient with comminuted fracture of the ulna only. The clinical results were excellent. The DASH score ranged between 0 and 36 points.

Conclusion:

This new interlocking nail may be considered as an alternative to plate osteosynthesis for fractures of the forearm in adults. The advantages are benefit of closed reduction, smaller residual scar, reduced cost and early union with allowance of immediate movements.     

Precise nail tip positioning after tibial intramedullary nailing prevents anterior knee pain

Purpose

Anterior knee pain (AKP) is a common complication following intramedullary nailing of tibial shaft fractures. Our aim was, by analysing the postoperative lateral knee X-rays and clinical status (VAS score), to find the best intramedullary tip position of a non protruded nail that will provide the best postoperative outcome avoiding AKP.

Methods

We evaluated the postoperative outcome of 221 patients, from the last four years, with healed fractures initially treated with intramedullary reamed nails with two or three interlocking screws proximally and distally through a medial paratendinous incision for nail entry portal. Our aim was to analyse a possible relationship between AKP according to the VAS scale, and nail position marked as a distance from tip of nail to tibial plateau (NP) and to tibial tuberosity (NT), measured postoperatively on lateral knee X-rays.

Results

Two groups of patients were formed on the basis of presence of pain related to AKP (the level of pain was neglected): group A were patients with pain and group B without pain. The difference between the two groups concerning NP and NT measurements appeared to be statistically significant concerning NT measurement (p < 0.05), with high accuracy according to the classification tree.

Conclusions

We presume that the position of the proximal tip of the nail and its negative influence on the innervation pattern of the area dorsal to patellar tendon could be the key factor of AKP. We conclude that the symptoms of AKP will not appear if the tip of the nail position is more than 5.5 mm from the tibial plateau (NP) and more than 2.5 mm from the tibial tuberosity (NT).     

A biomechanical study of conventional acetabular internal fracture fixation versus locking plate fixation

Background

Conventional internal fixation entails the use of an interfragmentary lag screw along with a plate. Not all acetabular fractures are amenable to the placement of an interfragmentary lag screw, and the fracture may be displaced during tightening of the interfragmentary lag screw. Locking plates are a possible solution. We sought to determine whether a locking plate construct can provide stability equivalent to that provided with a conventional construct for transverse acetabular fractures.

Methods

We used 5 paired fresh-frozen cadaveric acetabula. We fixed one side with the conventional technique and the other side with a locking plate. We subjected each fixation to a cyclic compressive force up to 500 cycles, followed by compressive force until failure. We monitored 3-dimensional motion of the fracture.

Results

The average fracture gap at 50 N compressive force after 500 loading cycles was 0.41 (standard deviation [SD] 0.49) mm for the conventional plate and lag screw construct compared with 0.76 (SD 0.62) mm for the locked plate construct (p = 0.46). The force to failure, as defined by 2 mm of fracture gap, was 848 (SD 805) N for the conventional plate and lag screw construct compared with 506 (SD 277) N for the locked plate fixation (p = 0.34).

Conclusion

The locking plate construct is as strong as the conventional plate plus interfragmentary lag screw construct for fixing transverse acetabular fractures. Locking plates may improve management of acetabular fractures by eliminating the need for placement of an interfragmentary lag screw. Furthermore, they may be helpful in revision hip arthroplasty in patients with pelvic discontinuity.     

The use of external fixation combined with vacuum sealing drainage to treat open comminuted fractures of tibia in the Wenchuan earthquake

Purpose

The purpose of this study was to review the results of external fixation combined with vacuum sealing drainage (VSD) to treat patients who sustained tibial and fibular fractures in the Wenchuan earthquake.

Methods

We retrospectively analysed 179 cases (of which 85 were classified as Gustilo grade III) of open comminuted fracture of the tibia and fibula caused by the Wenchuan earthquake. The patients were followed up for an average of 15 months; detailed records were kept on their function and recovery.

Results

After caring for the life-threatening injuries; fractures were treated by external fixation, with VSD used on the surface or in the cavity of the wound after debridement. Antibiotics were administered on the basis of drug sensitivity test results. After the infection had been controlled and healthy granulation tissue had developed, the patients underwent secondary suture, free skin grafting, or skin flap transfer.

Conclusion

Good results can be achieved when external fixation combined with vacuum sealing drainage were used to treat open comminuted fractures of tibia and fibula in the Wenchuan earthquake.     

An unusual stress fracture: Bilateral posterior longitudinal stress fracture of tibia

INTRODUCTION

Stress fractures (SF) occur when healthy bone is subjected to cyclic loading, which the normal carrying range capacity is exceeded. Usually, stress fractures occur at the metatarsal bones, calcaneus, proximal or distal tibia and tends to be unilateral.

PRESENTATION OF CASE

This article presents a 58-year-old male patient with bilateral posterior longitudinal tibial stress fractures. A 58 years old male suffering for persistent left calf pain and decreased walking distance for last one month and after imaging studies posterior longitudinal tibial stress fracture was detected on his left tibia. After six months the patient was admitted to our clinic with the same type of complaints in his right leg. All imaging modalities and blood counts were performed and as a result longitudinal posterior tibial stress fractures were detected on his right tibia.

DISCUSSION

Treatment of tibial stress fracture includes rest and modified activity, followed by a graded return to activity commensurate with bony healing. We have applied the same treatment protocol and our results were acceptable but our follow up time short for this reason our study is restricted for separate stress fractures of the posterior tibia.

CONCLUSION

Although the main localization of tibial stress fractures were unilateral, anterior and transverse pattern, rarely, like in our case, the unusual bilateral posterior localization and longitudinal pattern can be seen.     

Treatment of distal tibial shaft fractures by three different surgical methods: a randomized,prospective study

Purpose

A few studies focused on the methods of treatment for displaced distal tibial shaft fractures have been published, all of which compared two different methods. In this randomized, prospective study, we aimed to compare minimally invasive plate osteosynthesis, locking intramedullary nail stabilization and external fixation combined with limited open reduction and absorbable internal fixation for distal tibial shaft fractures by assessing complications and secondary procedures.

Methods

From November 2002 to June 2012, 137 skeletally mature patients with displaced distal tibial shaft fractures with or without fibula fracture were randomized to be treated by minimally invasive plate osteosynthesis (group A, n = 46), locking intramedullary nail (group B, n = 46) or external fixation combined with limited open reduction and absorbable internal fixation (group C, n = 45). Age, gender, mechanism of injury, fracture pattern and presence of open fracture were equally distributed among the three groups. Indexes for evaluation included hospital stay, operative time, time to radiographic union, union status, infection and the incidence of re-operation. Mazur ankle score was introduced for functional evaluation. Statistics Analysis System (SAS) 9.2 was used for analysis.

Results

A total of 121 patients were included in the final analysis (group A 42, group B 40 and group C 39) and evaluated after a mean of 14.8 months follow-up. There was no significant difference (P > 0.05) in hospital stay, time to radiographic union and the incidence of union status among the three groups. Although group C was associated with less secondary procedures versus groups A and B, it was related with more pin tract infections (15.4 %). Anterior knee pain occurred frequently after locking intramedullary nailing (37.5 %) and the irritation symptoms were more frequently encountered in group A (59.5 %). There was no difference in ankle function between the three methods after operation (P > 0.05).

Conclusions

We consider that the minimally invasive plate osteosynthesis, locking intramedullary nail stabilization and external fixation combined with limited open reduction and absorbable internal fixation techniques are all efficient methods for treating distal tibia fractures. With its wide indications, external fixation combined with limited open reduction and absorbable internal fixation leads to minimal soft tissue complication, good functional result and no local soft tissue irritation or implant removal.     

A Comparison of the Fixation Strengths Provided by Different Intraosseous Tendon Lengths during Anterior Cruciate Ligament Reconstruction: A Biomechanical Study in a Porcine Tibial Model

Background

The purpose of this study was to determine the tibial fixation strength provided by different intraosseous soft tissue graft lengths within the tibial tunnel.

Methods

Porcine tibial bones and digital flexor tendons were used for testing. Bone mineral densities of proximal tibial medial condyles were measured, and two-strand tendon bundles of 8 mm diameter were used. An intraosseous graft length of 2 cm was used in group 1 (n = 10), and a graft length of 4 cm was used in group 2 (n = 10). Tunnels were 4 cm in length and 8 mm in diameter. Tibial fixation was performed using a suture tied around a screw post with a washer and an additionally inserted 7 × 20 mm bioabsorbable screw. After applying preconditioning loading of 10 cycles, 1,000 cycles between 70-220 N were applied at a frequency of 1 Hz. Graft slippage and total graft movement were recorded. Ultimate tensile strength was measured by pull-out testing at an Instron crosshead speed of 1,000 mm/min.

Results

No significant intergroup difference was found for total graft movement after cyclic loading (slippage in group 1, 1.2 mm and group 2, 1.2 mm, respectively, p = 0.917; and total graft movement in group 1, 3.3 mm and group 2, 2.7 mm, respectively, p = 0.199). However, mean ultimate tensile strength in group 2 was significantly higher than that in group 1 (group 1, 649.9 N; group 2, 938 N; p = 0.008).

Conclusions

In a porcine model, ultimate tensile strength was greater for a 4 cm long intraosseous flexor tendon in the tibial tunnel. However, no intergroup difference in graft slippage or total graft movement was observed. The results show that a 2 cm intraosseous graft length in the tibial tunnel is safe and has sufficient strength (> 450 N) for adequate rehabilitation after anterior cruciate ligament reconstruction.     

Posterior cruciate ligament recruitment affects antero-posterior translation during flexion gap distraction in total knee replacement: An intraoperative study involving 50 patients

Background and purpose

Because of the oblique orientation of the posterior cruciate ligament (PCL), flexion gap distraction could lead to anterior movement of the tibia, which would influence the tibiofemoral contact point. This would affect the kinematics of the TKR. We assessed the flexion gap parameters when the knee is distracted during implantation of a PCL-retaining TKR. Furthermore, the effects of PCL elevation (steep or flat) and collateral ligament releases on the flexion gap parameters were determined.

Methods

During a ligament-guided TKR procedure in 50 knees, the flexion gap was distracted with a double-spring tensor with 200N after the tibia had been cut. The flexion gap height, anterior tibial translation, and femoral rotation were measured intraoperatively using a CT-free navigation system.

Results

During flexion gap distraction, the greatest displacement was seen in anterior-posterior direction. Mean ratio between increase in gap height and tibial translation was 1 to 1.9, and was highest for knees with a steep PCL (1 to 2.3). Knees with a flat PCL and knees with a ligament release had a larger increase in PCL elevation when the gap was distracted.

Interpretation

When the PCL is tensioned, every extra mm that the flexion gap is distracted can be expected to move the tibia anteriorly by at least 1.7 mm (flat PCL), or more if there is a steep PCL. This changes the tibiofemoral contact point, which may have consequences for polyethylene wear.     

Proximal fibula resection in the treatment of bone tumours

Background and objectives

We present a large study of patients with proximal fibula resection. Moreover we describe a new classification system for tumour resection of the proximal fibula independent of the tumour differentiation.

Methods

In 57 patients the functional and clinical outcomes were evaluated. The follow-up ranged between six months and 22.2 years (median 7.2 years). The indication for surgery was benign tumours in ten cases and malignant tumours in 47 cases. In 13 of 45 patients, where a resection of the lateral ligament complex was done, knee instability occurred. In 32 patients a resection of the peroneal nerve with resulting peroneal palsy was necessary.

Results

Patients with peroneal resection had significantly worse functional outcome than patients without peroneal resection. An ankle foot orthosis was tolerated well by these patients. Three of four patients with pathological tibia fracture had local radiation therapy. There was no higher risk of tibia fracture in patients with partial tibial resection.

Conclusions

Resection of tumours in the proximal fibula can cause knee instability, peroneal palsy and in cases of local radiation therapy, a higher risk of delayed wound healing and fracture. Despite the risks of proximal fibula resection, good functional results can be achieved.     

Infrapatellar vs. suprapatellar approach to obtain an optimal insertion angle for intramedullary nailing of tibial fractures

Background

During intramedullary nailing of tibial fractures, the insertion angle of the nail is of great importance. When the nail impacts the posterior cortex due to a large insertion angle with a dorsal target course, higher insertion forces are needed, and the danger of iatrogenic fractures increases. Accordingly, the insertion direction should be as parallel as possible to the longitudinal axis of the tibia. We aimed to confirm the hypothesis that intramedullary nailing of tibial fractures can be performed with smaller insertion angles via a suprapatellar approach rather than infrapatellar approach.

Methods

In 19 human bodies of donors with intact tibiae, we performed intramedullary nailing by both a suprapatellar and an infrapatellar approach. The correct entry point was determined by fluoroscopy. Subsequently, the medullary canal was reamed up to a diameter of 10 mm, and a 9 mm polytetrafluorethylen tube was inserted instead of a tibia nail. The angle between the proximal aspect of the tube and the longitudinal axis of the tibia was measured using a computer-assisted surgery system.

Results

The angle between the proximal aspect of the inserted tube, simulating the tibial nail, and the longitudinal tibial axis was significantly larger when using the infrapatellar approach.

Conclusions

We achieved an insertion angle significantly more parallel to the longitudinal axis when using a suprapatellar approach for intramedullary nailing of tibial fractures. Thereby, both the risk of iatrogenic fracture of the posterior cortex and apex anterior angulation of the short proximal fragment can be reduced during intramedullary nailing of tibial fractures.

     

Biomechanical comparison of intramedullar versus extramedullar stabilization of intra-articular tibial plateau fractures

Background

Fractures of the proximal tibia occur very often and are a great challenge for trauma surgeons to stabilize. Although locked nails were developed to stabilize these fractures, this technique has not been sufficiently investigated. The purpose of this study was to biomechanically assess the stability of locked intramedullary nailing compared to locked plating.

Methods

16 fresh frozen human cadaveric tibiae were osteotomized in the meta-diaphyseal intersection with an osteotomy gap of 10 mm and a single osteotomy through the medial epicondyle to simulate a 41-C.2 fracture. Stabilization was performed with an angle stable locked Targon-TX nail (n = 8) and two additional canulated screws. The other testing group (n = 8) was treated with two canulated screws and a five-hole LCP-PLT. The bones were tested in a cyclic testing protocol with increasing loads under compression and a load sharing of 60 % through the medial tibial plateau and 40 % to the lateral side. Stiffness and fracture gap movement were measured and failure mode was assessed.

Results

No significant differences were found between the two implants regarding load until failure. The stiffness of the intramedullary nailing group (927 N/mm) was statistically significantly higher than the stiffness of the plating group (564 N/mm). No differences were found for fracture gap movement in the z-axis. However, differences were found for dislocation of the proximal-lateral and proximal-medial fragments, with absolute values of 0.099 mm in the plate group and 0.66 mm in the nailing group at 800 N. Prior to failure, fracture gap movement was 0.22 mm for the plating group and 1.66 mm for the nailing group, a difference that was also statistically significantly different. The nailing group failed by screw cut-out while the plating group failed by screw breakage.

Conclusion

Nailing of proximal tibia fractures leads to a stiffer implant-bone construct than plating. Since no adverse effects were found after nailing it seems to be a good alternative to plating for intra-articular proximal tibia fractures, especially in patients with soft tissue problems.     

Expandable self-locking nail in the management of closed diaphyseal fractures of femur and tibia

Background:

Intramedullary fixation is the treatment of choice for closed diaphyseal fractures of femur and tibia. The axial and rotational stability of conventional interlocking nails depends primarily on locking screws. This method uses increased operating time and increased radiation exposure. An intramedullary implant that can minimize these disadvantages is obviously better. Expandable intramedullary nail does not rely on interlocking screws and achieves axial and rotational stability on hydraulic expansion of the nail. We analyzed 32 simple fractures of shaft of femur and tibia treated by self-locking expandable nail.

Materials and Methods:

Intramedullary fixation was done by using self-locking, expandable nail in 32 patients of closed diaphyseal fractures of tibia (n = 10) and femur (n = 22). The various modes of injury were road traffic accidents (n = 21), fall from height (n = 8), simple fall (n = 2), and pathological fracture (n = 1). Among femoral diaphyseal fractures 16 were males and six females, average age being 33 yrs (range, 18- 62 yrs). Seventeen patients had AO type A (A1 (n = 3), A2 (n = 4), A3 (n = 10)) and 5 patients had AO type B (B1 (n = 2), B2 (n = 2), B3 (n = 1)) fractures. Eight patients having tibial diaphyseal fractures were males and two were females; average age was 29.2 (range, 18- 55 yrs). Seven were AO type A (A1 (n = 2), A2 (n = 3), A3 (n = 2)) and three were AO type B (B1 (n = 1), B2 (n = 1), and B3 (n = 1)). We performed closed (n = 27) or open reduction (n = 5) and internal fixation with expandable nail to stabilize these fractures. The total radiation exposure during surgery was less as no locking screws were required. Early mobilisation and weight-bearing was started depending on fracture personality and evidences of healing. Absence of localised tenderness and pain on walking was considered clinical criteria for union, radiographic criteria of union being continuity in at least in three cortices in both AP and lateral views. Patients were followed for at least one year.

Results:

The average operative time was 90 min (range, 55-125 min) for femoral fractures and 53 min (range, 25-115 min) for tibial fractures. Radiation exposure was minimum, average being 84 seconds (range, 54-132) for femoral fractures and 54 seconds (range, 36-78) for tibial fractures. All fractures healed, but few had complications, such as infection (one case with tibial fracture) bent femoral nail with malunion (n = 1), and delayed union (n = 3; 2 cases in femur and 1 case in tibia). Mean time of union was 5.1 months (range, 4-10½ months) for femoral fractures and 4.8 months (range, 3-9 months) for tibial fractures.

Conclusion:

We found the nail very easy to use with effective fixation in AO type A and B fractures in our setting. Less surgical time is required with minimum complications. The main advantage of the expandable nail is that if affords. satisfactory axial, rotatory, and bending stability with decreased radiation exposure to operating staff and the patient.     

Injury Risk to Extraosseous Knee Vasculature During Osteotomies: A Cadaveric Study With CT and Dissection Analysis

Background

Realignment osteotomies about the knee may be performed as distal femoral or proximal tibial osteotomies; both may be performed either on the medial or lateral sides of the knee, in closing- or opening-wedge fashion. Although rare, injury to neurovascular structures may occur, and the proximity of the vascular structures to the osteotomy saw cuts has been incompletely characterized.

Questions/purposes

We performed a cadaver study to assess the risk of vascular injury in patients undergoing realignment osteotomies by (1) quantifying the distances between osteotomy saw cuts and blood vessels using three-dimensional CT reconstruction after distal femoral and proximal tibial osteotomies; and (2) qualitatively describing the small- and medium-sized vasculature around the knee, to provide the link between the CT analysis and wedge incision measures, and better show the potential extraosseous supply to the regions investigated.

Methods

Twelve human cadaveric knees were injected with a latex and barium sulfate suspension into the superficial femoral artery. Each specimen underwent CT to evaluate vascular perfusion and was randomized to either a lateral opening-wedge distal femoral osteotomy and medial opening-wedge proximal tibial osteotomy group, or a medial closing-wedge distal femoral osteotomy and lateral closing-wedge proximal tibial osteotomy group. Postoperatively, knees underwent CT in extension to measure the shortest distance between the osteotomies and the popliteal artery, anterior and posterior tibial arteries, and genicular arteries. Vessels between 5 mm and 10 mm from the osteotomy cut were considered in a zone of moderate risk for damage, while vessels less than 5 mm from the cut were considered in a zone of high risk for damage. Vessels more than 10 mm from the cut were not considered to be at risk. Subsequently, knees underwent dissection and chemical débridement to qualitatively describe the smaller vessels. This part of the study added visual information and gave a comprehensive overview of the vessels at risk.

Results

All variations of the osteotomies put at least one artery at risk. The popliteal artery was found in a risk zone for injury in two specimens during closing-wedge distal femoral osteotomy (median distance, 11.6 mm; range, 5.2–14.6 mm). The superior lateral genicular artery was in a risk zone in all the specimens during opening-wedge distal femoral osteotomy (median distance, 3.0 mm; range, 0.7–6.5 mm), and in five specimens during closing-wedge distal femoral osteotomy (median distance, 4.5 mm; range, 1.3–11.2 mm). A concomitant risk for superior medial genicular artery injury was observed in five specimens during opening-wedge distal femoral osteotomy (median distance, 8.7 mm; range, 0.8–13.9 mm) and in four specimens during closing-wedge distal femoral osteotomy (median distance, 4.1; range, 0.5–41.7 mm). The popliteal artery was in a risk zone in four specimens during opening-wedge proximal tibial osteotomy (median distance, 9.6 mm; range, 6.6–12.9 mm), and in three specimens during closing wedge proximal tibial osteotomy (median distance, 9.6 mm; range, 4.4–11 mm). The inferior medial genicular artery could be classified at risk in five specimens during opening-wedge proximal tibial osteotomy (median distance, 2.1 mm; range, 0.3–32 mm) and in five specimens during closing-wedge proximal tibial osteotomy (median distance, 5.8 mm; range, 1.4–13 mm). Furthermore, the inferior lateral genicular artery was found in a risk zone in two specimens of closing-wedge proximal tibial osteotomies (median distance, 17.4 mm; range, 8–23.3 mm). There were no differences between opening-wedge and closing-wedge distal femoral osteotomies and proximal tibial osteotomies in the vessels at risk during the procedure. After chemical débridement, knees showed abundant vascularization of the distal femur and lateral tibia, whereas the medial tibia contained few arteries.

Conclusions

With the numbers available, we found that none of the osteotomy techniques performed was safer than any other in terms of the proximity of the major arterial structures and some vessels appear to be at relatively high risk during these procedures.

Clinical Relevance

This study clarifies that the genicular arteries on the opposite side of the surgical field, which cannot be seen and protected during the procedure, can be at risk of injury, particularly when the cortical hinge is compromised. Additional studies are necessary to address the potential risk of the dissection needed for plate placement and injuries related to drilling and screw placement during osteotomies around the knee.