Defining a safe corridor for transcondylar screw insertion across the canine humeral condyle: a comparison of medial and lateral surgical approaches

Long-Term Outcome and Complications after Transcondylar Screw Placement for Canine Humeral Intracondylar Fissure

OBJECTIVE

 The aim of this study was to report postoperative complications and long-term outcomes following transcondylar screw placement for humeral intracondylar fissure (HIF).

STUDY DESIGN

 It was a retrospective single-centre case series. Medical records (2018-2022) were reviewed for dogs with HIF treated with transcondylar screw placement. Data collected included signalment, concurrent orthopaedic disease, partial or complete HIF, surgeon, surgical approach, surgical technique and implant type, transcondylar screw angulation, postoperative complications and outcomes. Long-term outcome was assessed with owner questionnaire, orthopaedic examination and follow-up radiography. Statistical analysis was performed to identify risk factors predisposing to a complication or a poor outcome.

RESULTS

 Forty-seven dogs (57 elbows) met the inclusion criteria; long-term follow-up was available in 41 dogs (50 elbows). Minor and major medical complications were noted in seven and three elbows respectively. The total complication rate was 17.5%. Increasing age was significantly associated with a reduced risk of postoperative complications (p = 0.0051). No other risk factors were identified. A postoperative complication was not associated with a less than full outcome (p = 0.5698).

CONCLUSION

 Transcondylar screw placement for HIF is associated with a low complication rate and good outcome.

Computed Tomography Topographical Analysis of Incomplete Humeral Intracondylar Fissures in English Springer Spaniel Dogs

OBJECTIVE

 The aim of this study was to use computed tomography (CT) images obtained from English springer spaniels (ESS) with different sizes of humeral intracondylar fissure (HIF) to describe the typical shape, origin and a possible propagation pattern of HIF in this breed.

STUDY DESIGN

 It is a retrospective analysis of 32 elbow CT from 27 ESS with incomplete HIF. Measurements included HIF articular surface length, centre of HIF at articular surface relative to the caudal edge of the supratrochlear foramen (CHIF), HIF depth and sagittal area of fissure. Measurement of isthmus area and diameter was obtained for each elbow. Humeral intracondylar fissure measurements were analysed as proportions of the isthmus. For parts of analysis, elbows were grouped by HIF area as a percentage of isthmus area (%HIF) into less than 20% (n = 10), 20 to less than 40% (n = 8), 40 to less than 60% (n = 9) and 60 to less than 90% (n = 5).

RESULTS

 The mean isthmus diameter was 12.31 mm (range: 10.96-13.69 mm). Mean CHIF for %HIF groups less than 20%, 20 to less than 40%, 40 to less than 60% and 60 to less than 90% were 57, 74, 86 and 96 degrees, respectively. The less than 20% group was significantly lower than 20 to less than 40% group (p = 0.035) and 40 to less than 60% and 60 to less than 90% groups (p < 0.001); the 20 to less than 40% group was significantly lower than the 60 to less than 90% group (p = 0.015). Humeral intracondylar fissure articular surface length increased in a sigmoidal fashion relative to %HIF, corresponding to segmental enlargement of the fissure as %HIF increases.

CONCLUSION

 In ESS, HIF typically originates approximately 57 degrees caudal to the supratrochlear foramen in the sagittal plane and may propagate in a segmental fashion with lesser propagation through the proximal intracondylar region.

Medial versus lateral transcondylar screw placement for canine humeral intracondylar fissures: A randomized clinical trial

OBJECTIVE

To determine the influence of screw direction on complications following transcondylar screw placement for the treatment of canine humeral intracondylar fissures (HIFs).

STUDY DESIGN

Equivalence, parallel group, randomized clinical trial.

SAMPLE POPULATION

Fifty-two client owned dogs (73 elbows).

METHODS

Transcondylar screw placement was randomized to either a medial or lateral approach. The primary outcome was the incidence of postoperative complications.

RESULTS

There were 37 cases in the lateral approach group and 36 cases in the medial approach group. There was a significantly greater proportion of postoperative complications following placement of transcondylar screws from a lateral to medial direction (p = .001). There were seven cases with complications (19%) in the medial approach group versus 23 cases with complications (62%) in the lateral approach group. The majority of complications were seromas (n = 13) and surgical site infections (n = 16) with 4 complications requiring further surgery. Implant area moment of inertia (AMI), normalized to bodyweight, was lower in dogs with a major complication (p = .037).

CONCLUSION

Transcondylar screws placed from lateral to medial for canine HIFs had a greater proportion of postoperative complications in this randomized clinical trial design. Implants with a lower AMI, relative to bodyweight, were more likely to lead to major complications.

CLINICAL SIGNIFICANCE

We recommend placing transcondylar screws from medial to lateral for canine HIFs to reduce the risk of postoperative complications. Relatively small diameter implants had an increased risk of major complications.

Correlation between the Insertion Side of a Transcondylar Screw for the Surgical Management of Humeral Intracondylar Fissures in Dogs and the Incidence of Postoperative Surgical Site Infection

OBJECTIVE

 An increased rate of surgical site infection (SSI) following treatment of canine humeral intracondylar fissure (HIF) with a lateromedially (LM) placed transcondylar screw (TCS) compared with a mediolateral (ML) TCS has been previously postulated. We hypothesized that the direction of insertion of the TCS would not affect the incidence of postoperative SSI.

STUDY DESIGN

 It was single-centre retrospective study. Dogs with HIF confirmed by computerized tomography, treated by TCS placement (between 2008 and 2019) and with a minimum follow-up of 12 weeks, were included. The following data were recorded: signalment, presenting clinical signs, direction of placement and size of the utilized TCS, surgical and anaesthetic times, concurrent surgical procedures, presence of concomitant elbow pathology, perioperative and postoperative antibiotic usage and postoperative complications. Recorded data were analysed with a multinomial logistic regression model with a p-value less than or equal to 0.05.

RESULTS

 Thirty-five dogs (46 elbows) met the inclusion criteria. Median clinical follow-up interval was 52 weeks. Seven of thirty-one elbows with a ML TCS, and 4/15 elbows with a LM TCS developed SSI. Four of nine dogs that underwent bilateral single-surgery TCS placement developed SSI unilaterally.

CONCLUSION

 No significant difference was shown in short-term SSI occurrence between the ML and the LM direction of placement of the TCS.

The effect of an aiming device on the accuracy of humeral transcondylar screw placement

OBJECTIVES

(1) To evaluate the accuracy of an aiming device on placement of humeral transcondylar screws compared to fluoroscopic methods. (2) To compare experience level on outcome.

STUDY DESIGN

Randomized, match pair, prospective ex-vivo study.

SAMPLE POPULATION

A total of 68 dogs.

METHODS

Canine cadaveric forelimbs were randomly assigned to either aiming device or fluoroscopic-guided groups, and to diplomate or resident. Digital radiography was used to evaluate screw trajectory deviation and eccentricity on the humeral condyle. Procedure time, outcome based on experience, and complications were recorded.

RESULTS

The aiming device screw trajectory angle was decreased in the right limb (1.9 ± 1.1°) compared with the left (3.6 ± 1.1°, p = .0178), and compared to fluoroscopy (3.4 ± 1.1° p = .0128). There was no difference between leg laterality with fluoroscopy (p = .9979). Trajectory angle was increased with resident versus diplomate (3.4 ± 1.1° and 2.5 ± 1.1° respectively, p = .0366). Eccentricity deviation was decreased using fluoroscopy versus aiming device (3.1 ± 0.36 mm, 4.2 ± 0.36 mm, respectively, p = .0017). The risk of joint involvement was 8 times greater in aiming device groups, though not significant (p = .0575). Significant complications included increased drill attempts in fluoroscopic groups (p = .0237).

CONCLUSION

The aiming device provided accurate placement of transcondylar screws, in terms of both position on the condyle and trajectory angle. Results were similar to fluoroscopic-guided method.

CLINICAL SIGNIFICANCE

An aiming device is an acceptable means of placing humeral transcondylar screws. The use of the aiming device had an eight times increased risk of joint involvement compared to fluoroscopy.

Defining the safe corridor for transcondylar screw placement in the feline humeral condyle

OBJECTIVES

The aim of this study was to develop guidelines for the optimal location of drill entry and exit points for insertion of a transcondylar screw across the feline humeral condyle.

METHODS

Multiplanar reconstruction of feline elbow CT scans performed between 2016 and 2021 at one referral institution were reviewed. The optimum medial and lateral epicondylar entry and exit points for transcondylar screw placement were determined. These values were normalised to the humeral condylar diameter (HCD) for each elbow to determine the transcondylar screw placement guidelines. These guidelines were applied to each elbow and tolerance angles were determined in the transverse and frontal plane CT images to determine the safe corridor for screw placement.

RESULTS

Twenty elbows from 12 cats were evaluated in this study. The guidelines for transcondylar screw placement were as follows: the medial entry/exit point was 0.38 × HCD cranial and 0.16 × HCD distal to the medial epicondyle, and the lateral entry/exit point was 0.3 × HCD cranial and 0.16 × HCD distal to the lateral epicondyle. Tolerance angles were statistically significantly (P <0.05) larger in both frontal (34.5% larger) and transverse (21.1% larger) planes when drilled from a lateral to medial direction compared with drilling from a medial to lateral direction.

CONCLUSIONS AND RELEVANCE

The guidelines determined from this study may aid clinicians in the placement of humeral transcondylar screws in cats. Where possible, drilling from a lateral to medial direction is recommended owing to the higher tolerance angles reducing the likelihood of articular surface damage. Further studies are warranted to determine whether these guidelines are clinically useful and result in the safe insertion of a transcondylar screw in the clinical setting.

Medial epicondylar fissure fracture as a complication of transcondylar screw placement for the treatment of humeral intracondylar fissure

OBJECTIVE

To report the incidence of medial epicondylar fissure fracture (MEFF) after medial-to-lateral transcondylar screw placement in dogs with humeral intracondylar fissure (HIF) and to identify risk factors for MEFF.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Seventy-four client-owned dogs (88 elbows).

METHODS

Medical records of dogs surgically treated for HIF, and postoperative imaging studies were reviewed for demographics, fracture characteristics, and repair techniques. The width of the transcondylar screw was expressed relative to the height of the condyle. Screw angle and degree of countersinking were recorded. Information from case records and follow-up radiographs were used to identify complications.

RESULTS

Medial epicondylar fissure fracture was identified in 10 elbows (11.4%) following medial-to-lateral transcondylar screw placement: 4 cases were detected intraoperatively, 2 on immediate postoperative radiographs, 1 during routine radiographic follow up, and 3 when radiographs were reviewed for this study. A larger relative screw size was found to increase the risk of MEFF (P = .004, OR = 1.5). Fifteen additional complications were identified in 13/80 elbows at a median of 6 weeks postoperatively (range 1-56 weeks). Screw loosening was the most frequent complication (n = 9) and was the only complication in dogs with MEFF (n = 3); MEFF tended to increase the risk of perioperative screw loosening (P = .06).

CONCLUSION

Medial epicondylar fissure fracture occurred in 10/88 elbows treated for HIF and was more common in elbows treated with a larger screw size relative to the height of the condyle.

CLINICAL SIGNIFICANCE

Placing transcondylar screws with a diameter inferior to 41% of the height of the condyle is recommended to avoid MEFF. Medial epicondylar fissure fracture appears to have a low clinical significance in the perioperative period, although its effect on long-term outcome remains unknown.

Biomechanical comparison of humeral condyles with experimental intracondylar fissures immobilized with a transcondylar positional or a lag screw: An ex-vivo study in dogs

OBJECTIVE

To compare the axial biomechanical properties of intracondylar humeral osteotomies fixed with 4.5 mm transcondylar positional or cortical lag screws.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Paired humeri from 21 canine cadavers.

MATERIALS AND METHODS

An intracondylar osteotomy was created on each humerus to mimic an intracondylar fissure. Paired humeri were randomly assigned to fixation with a positional or a lag screw. All specimens were radiographed postinstrumentation to document proper screw placement. Axial load was applied to the distal articular surface of the trochlea at a rate of 1 mm/s until a 40% decrease in load was measured. Specimens were assessed for mode of failure with visual inspection and radiographs.

RESULTS

Stiffness (1236.7 ± 181 N/mm vs. 1050.8 ± 265 N/mm), yield load (3284.3 ± 1703 N vs. 2071.1 ± 740 N), and maximum load (7378.0 ± 1288 vs. 5793.7 ± 2373 N) were greater in constructs fixed with a positional rather than a lag screw (p = .0008, .044, and .040, respectively).

CONCLUSION

In our model, mechanical properties were improved when the transcondylar osteotomy was stabilized with a 4.5 mm positional screw rather than a lag screw.

CLINICAL SIGNIFICANCE

This ex vivo study suggests that a transcondylar lag screw and positional screw are not biomechanically equal. Additional in vivo studies are need to help with clinical decision making when prophylactically treating HIF.

Accuracy of medial-to-lateral transcondylar screw placement using an aiming device and preoperative computer tomography planning for the treatment of humeral intracondylar fissure

OBJECTIVE

To determine the accuracy of transcondylar screws placed from medial-to-lateral using preoperative planning on computed tomography (CT) and an aiming device in elbows with humeral intracondylar fissures (HIFs).

STUDY DESIGN

Retrospective case series.

ANIMALS

Twenty-five client-owned dogs with HIF.

METHODS

A 4.5-mm transcondylar screw was placed in 34 elbows with HIF. humeral condylar diameter (HCD) was measured at the humeral condylar isthmus on CT. Entry and exit points were planned at 0.3 × HCD cranial and 0.2 × HCD distal to the medial epicondyle and 0.3 × HCD cranial and 0.3 × HCD distal to the lateral epicondyle. An aiming device was used to guide drilling from the medial entry point to the lateral exit point. The difference between planned and actual screw entry and exit points, and the angular deviation of the actual screw axis from the planned screw axis, was assessed on the postoperative CT scans.

RESULTS

Thirty-three out of 34 screws were completely within the humeral condyle. Thirteen out of 34 screws were placed less than 2 mm from planned entry and exit points in both the transverse and the frontal plane. The axis of the screw deviated by a mean of 3.2° (transverse plane) and 3.5° (frontal plane) from the planned axis.

CONCLUSION

Humeral transcondylar screws placed with the technique tested here were entirely within the humeral condyle in 33 out of 34 elbows.

CLINICAL SIGNIFICANCE

Use of CT planning and an aiming device allows accurate placement of transcondylar screws from medial-to-lateral in dogs with HIF.

Humeral intracondylar fissures in French bulldogs

BACKGROUND

French bulldogs have previously been reported to be at an increased risk of developing humeral condylar fractures (HCF). Humeral intracondylar fissures (HIF) are thought to be a predisposing factor for HCF occurrence in skeletally mature dogs particularly when the fracture occurs during normal activity. We hypothesised that HIF may be a predisposing factor for HCF in French bulldogs.

METHODS

A retrospective case series of nine French bulldogs that had sustained HCF and where CT was performed prior to surgery.

RESULTS

Five of the fractured humeri had sclerosis adjacent to the fracture site. Six of the contralateral intact humeri were diagnosed with HIF on the basis of a partial (2/6) or complete (4/6) hypoattenuating area extending between the distal articular surface and the supratrochlear foramen in the sagittal plane, with adjacent sclerosis (6/6).

CONCLUSIONS

Recognition of sclerosis at the intracondylar fracture surface on CT can prompt suspicion that HIF preceded HCF. A predisposing HIF has potentially great clinical significance for this breed if we draw parallels with breeds such as the springer spaniel for whom HIF and HIF-associated condylar fracture is well documented.

Influence of interlocking thread screws to repair simulated adult canine humeral condylar fractures

OBJECTIVE

To determine the influence of interlocking screw threads on the biomechanical properties of repaired canine humeral condylar fractures.

STUDY DESIGN

Ex vivo biomechanical study.

SAMPLE POPULATION

Thirty-six humeral condyles.

METHODS

Simulated fractures of the lateral aspect of the humeral condyle were stabilized by a 3.5 mm interlocking thread screw (ITS) or 3.5 mm buttress thread screw placed in lag (BTS-L) or positional fashion (BTS-P) and axially loaded at a walk, trot, 2-mm displacement, and failure cycles. Compact flute drill bits (CFBs) were used for ITS constructs and standard flute drill bits (SFB) for BTS constructs. The effects of bit type on drilling parameters and screw type on screw insertion properties and fragment stability were assessed.

RESULTS

CFB produced a 6°C greater temperature increase (p = .042) and required 20 N higher torque (p = .003) than SFB. Insertional torque was greater for ITS than BTS-P (p = .001) and BTS-L (p = .001). Condylar fragment rotation at failure was lower in ITS (lsmean ± SE, 8.3° ± 1.9°) than BTS-L constructs (14.5° ± 2.3°, p = .011). ITS resisted greater loads (1503 ± 105 N) than BTS-P (1189 ± 99 N, p = .038) but not BTS-L (1249 ± 123 N, p = .121) constructs.

CONCLUSION

Biomechanical performance of constructs was improved with ITS rather than BTS fixation.

CLINICAL SIGNIFICANCE

ITS can be considered for stabilization of humeral condylar fractures in adult dogs.

Humeral Intracondylar Fissure in Dogs

Humeral intracondylar fissure (HIF) was first described as incomplete ossification of the humeral condyle. It is now known that the fissure is a stress fracture in some dogs. The descriptive term HIF is therefore preferred. In young dogs an incomplete ossification cause may still be valid. Symptomatic HIF is treated surgically with a transcondylar implant. The aim is to alleviate lameness and avoid condylar fracture. Choosing an appropriate surgical approach and implant can reduce complications. HIF is not always symptomatic and, in these cases, surgical management is more controversial, because a minority of such cases become lame or fracture.

Comparing the accuracy of freehand, fluoroscopically guided and aiming device-assisted drilling in veterinary orthopaedic surgery

BACKGROUND

Drilling accuracy is essential in the correct positioning of implants and avoidance of iatrogenic damage to surrounding tissues. The use of augmented drilling methods has been documented as an approach to improving the accuracy of drilling. The aim of this study was to compare the accuracy of two augmented drilling methods (fluoroscopically guided and aiming device) to freehand (FH) drilling.

METHODS

Three experienced specialist surgeons and three veterinary surgeons without primary orthopaedic experience drilled into synthetic bone towards a target using the three different methods at three different angles (0°, 10° and 20°). The duration of drilling was recorded, and the accuracy of drilling was measured using photographs before and after drilling.

RESULTS

The two augmented methods were more accurate than FH drilling in synthetic bone, with the aiming device producing the greatest accuracy. Increased angulation of drilling decreased the drilling accuracy. Surgeon experience did not impact on drilling accuracy. Surgeon inexperience and augmented drilling methods both increased the time taken to drill.

CONCLUSION

The use of augmented drilling methods improved the accuracy of drilling, and surgeons should consider their use when drilling in anatomical regions where the margin of error is small.

Accuracy of three-dimensional printed patient-specific drill guides for treatment of canine humeral intracondylar fissure

OBJECTIVE

To determine the accuracy of three-dimensional printed patient-specific drill guides (3D-PDG) as treatment of humeral intracondylar fissures (HIF) in dogs.

STUDY DESIGN

Retrospective consecutive case series.

ANIMALS

Client-owned dogs with HIF treated with a 5-mm transcondylar screw (TCS) placed from medial to lateral with a 3D-PDG.

METHODS

The proposed TCS entry point and trajectory were planned using computed tomography (CT) data and computer-aided design software (CAD), and a 3D-PDG was produced. During surgery the 3D-PDG was used to drill the pilot hole from medial to lateral; the guide was then removed, the pilot hole was overdrilled, and a 5-mm TCS was placed. Postoperative CT data were imported into CAD software, and the entry points, exit points, and trajectories were compared between the planned and actual screw locations.

RESULTS

Sixteen elbows from 11 dogs were included. Mean (SD) entry point translation was 1.3 mm (0.64), with all screws entering cranial to the proposed location. Mean maximum screw angulation was 5.2° (2.10°), with most screws directed caudodistal to the desired trajectory. Mean (SD) exit point translation was 1.8 mm (0.89) from the planned location. There was no intra-articular screw placement.

CONCLUSION

Use of a 3D-PDG permitted accurate placement of a mediolateral 5-mm locking TCS within the humeral condyle.

CLINICAL SIGNIFICANCE

Three-dimensional printed patient-specific drill guides should be considered as accurate and consistent for placing TCS for treatment of HIF in dogs.

Long-term outcome following management of canine humeral intracondylar fissure using a medial approach and a cannulated drill system

This study evaluated the feasibility, complications and long-term outcomes of using a cannulated drill system combined with intraoperative imaging to place a transcondylar screw for the management of canine humeral intracondylar fissure. Thirteen dogs were enrolled, with one dog undergoing staged bilateral surgery. No intraoperative complications occurred. Five minor (36%) and three major (21%) postoperative complications occurred, giving an overall complication rate of 57%. None of the screws placed penetrated the articular surface. The mean duration of surgery was 28 min (SD ±3.5) for dogs that developed a major complication versus 46 min (SD ±18.1) for those that did not (p=0.015). The duration of preoperative lameness was significantly shorter for cases which suffered a major complication (2 days; SD ±2.8) than those that did not (34 days; SD ±31.7, p=0.008). None of the variables assessed were significantly associated with minor complications. Median time from surgery to last follow-up was 5.8 years (range 3.5-8.5 years). Median Liverpool Osteoarthritis in Dogs questionnaire score at the final point of follow-up was 16 (range 7-27). A significant number of patients were found to require analgesia at long-term follow-up.

Can a surgeon drill accurately at a specified angle?

Objectives

To investigate whether a surgeon can drill accurately a specified angle and whether surgeon experience, task repetition, drill bit size and perceived difficulty influence drilling angle accuracy.

Methods

The sample population consisted of final-year students (n=25), non-specialist veterinarians (n=22) and board-certified orthopaedic surgeons (n=8).

Each participant drilled a hole twice in a horizontal oak plank at 30°, 45°, 60°, 80°, 85° and 90° angles with either a 2.5  or a 3.5 mm drill bit. Participants then rated the perceived difficulty to drill each angle. The true angle of each hole was measured using a digital goniometer.

Results

Greater drilling accuracy was achieved at angles closer to 90°. An error of ≤±4° was achieved by 84.5 per cent of participants drilling a 90° angle compared with approximately 20 per cent of participants drilling a 30–45° angle. There was no effect of surgeon experience, task repetition or drill bit size on the mean error for intended versus achieved angle. Increased perception of difficulty was associated with the more acute angles and decreased accuracy, but not experience level.

Clinical significance

This study shows that surgeon ability to drill accurately (within ±4° error) is limited, particularly at angles ≤60°. In situations where drill angle is critical, use of computer-assisted navigation or custom-made drill guides may be preferable.