corrective measures lengthening of fourth brachymetatarsia

Review of:

Lengthening of Fourth Brachymetatarsia

Three Different Surgical Techniques

By Chris Lim

RECAP

Recap

Purpose: Assess the clinical results of lengthening the fourth metatarsal in brachymetatarsia using three different surgical techniques

Hypothesis: Unclear/Not StatedRetrospective Study153 feet, 106 pts ( 100 female, 6 males)Mean age: 26.3 years (13-48)

Recap

Group 1: One-Stage Intercalary bone graft, secured by an IM K-Wire (45 feet, 35 pts)

Group 2: Gradual lengthening with a Mini-External Fixator after performing an Osteotomy with a saw (59 feet, 39 pts)

Group 3: Gradual lengthening using a Mini-external Fixator after an Osteotomy with an Osteotome (49 feet, 32 pts)

RESULTS

Results Table I: Details of patients in each group

• Note: “n” (sample size) is based on number of people• Mean age in years proved significance in all three groups, based on p-value• Patients with bilaterality did not prove significance.• Number of females did not prove significance based on p-value

May be acceptable due to the epidemiology behind Brachymetatarsia Brachymetatarsia is more common in females Female:Male ratio is 25:1

ResultsTable II: Pre-Operative Variables

Pre-op Percentage of the length of 4th metatarsal to the 2nd metatarsal - proved significant

Pre-op Shortness of 4th toe - proved significant Note: “n” (sample size) is based on number of feet

ResultsTable III: Post-Operative Variables

Length gain for all three groups proved significance based on p-valueLength gain (%) was insignificant based on p-value

Percentage increase= lengthening obtained/ pre-operative length

Healing Index (wks/cm) was insignificant based on p-valueFixation time for all three groups proved significance based on p-value Note: 8 participants were disregarded due to failure of bone formation

ResultsTable IV: Post-Operative Variables, based on AOFAS Score

AOFAS Score was insignificant based on p-valueCould be due to variance in pain tolerance levels in patientsAOFAS is based on Pain, Function, and Alignment

Subject Satisfaction score and Willingness was statistically significant Note: All patients were considered for this data collection

Results – Pitfalls

Retrospective StudyLess control of variablesSampling Bias

Hypothesis: Not statedMean age of pts: 26.3 years (Ranging from 13 to 48 years old)

Large range can lead to discrepancies in results of study (e.g., satisfaction survey and overall healing time)

Results – Pitfalls

Study was not randomizedSelection bias

Patients were offered a choice of which treatment they wanted to undergo

Researcher biasPatient’s choice in treatment “may have been influenced by the

surgeon towards one-stage for pts with less shortening”

Results – Pitfalls

Sample size, “n,” was not consistent between the 4 tables In Table 1, “n” represented number of patientsIn Tables 2, 3, and 4, “n” represented number of feet

8 patients were disregarded in data collection post-operatively. However, in the Table 4, which compared both pre-op and post-op satisfaction and willingness to return, the 8 patients were taken into considerationSelection Bias

Results – Pitfalls

Discrepancy in metatarsal lengths between the groupsThe preoperative length and length gain of the fourth metatarsal in the bone-

graft group were less short than those of the patients in other groups.

Technique of osteotomy in gradual lengthening was changed after accumulating experience in the saw groupLeading to inconsistencyCompromises internal validityHarmed patients prior to change in procedure

Results – Pitfalls

The pre-operative AOFAS score was 100 in all patients, and it was reduced after surgery.The main cause was pain at the plantar aspect of the proximal phalanx or

at the metatarsophalangeal joint after prolonged standing or walking and decreased movement of this joint.

Despite this, the Willingness score was high (favorable)Inconsistency in data

Results – Pitfalls

Mean Follow-Up: 22 months - ranging from 7 months to 55 monthsNon-similar base-line measurements (range is too large)AOFAS, Satisfaction score, and Willingness may have been affected Recall bias may have occurs

DISCUSSION Section

DiscussionOne-Stage Lengthening: Advantages

Advantages of One Stage LengtheningNon requirement for a external fixatorNo possibility of insufficient bone formationNo necessity for manipulation of the external fixator after

surgery

DiscussionOne-Stage Lengthening: Disadvantages

Disadvantages of One Stage LengtheningLimited lengtheningImmobilization of the MPJ during consolidation of the graftNecessity for harvesting a bone graftAllograft may lack capacity to healMaceration (most common problem of the plantar aspect of the MPJ, Due

to plantar slope of the met, the 4th toe is immobilized in a plantar-flexed position promoting maceration)

DiscussionGradual Lengthening – Advantages

Advantages of Gradual Lengthening Ability to obtain greater length than one-stage

intercalary bone graftImmediate weight-bearing can occurPreservation of movement of the MPJBone Osteotome reduces soft tissue damage

DiscussionGradual Lengthening – Disadvantages

Disadvantage of Gradual LengtheningRegular adjustment of the external fixatorPossibility of insufficient bone formationRisk of pin-track infectionMicro-Saw method may cause local heat damage & necrosis

Micro-Saw

Non-specific to Surgical Tools

The Type and Model of the equipment used may cause variance to the results.

Compromise the External Validity in achieving the same results if the surgical techniques were repeated in a different location.

Eg. Osteotome used in the Osteotomy was not specified.

Classic Osteotome

Bone Scapel Osteotome

https://www.youtube.com/watch?v=EnODsIhHUVI

Discussion

In the conclusion, the gradual lengthening method was re-stated as being the most reliable.

However, in the Discussion section, only general references were made as to the basic advantages of the method, which were not specific to the study.

Author explained many limitations:Retrospective studySelection bias for preferred lengthening by surgeon may have occurred Technique in osteotomy was changed after accumulating experience in the saw group

Discussion – Pitfalls

Actual results were not discussed in this sectionThe Discussion section did not clearly match the Introduction in

comparing and concluding the most reliable result. Overall, without a hypothesis, it is hard to compare the purpose of

the study with their conclusion.

CONCLUSION

Conclusion

In conclusion, the gradual lengthening by distraction osteogenesis after osteotomy using an osteotome produces the most reliable results for the treatment of fourth brachymetatarsia.

Conclusion – Pitfalls

Previously, research question was not clearly stated.Hypothesis and null hypothesis was not stated.

Therefore, p-value credibility comes into questionp-value indicates whether or not there strong evidence against the null

hypothesisFunction of the p-value is to determine whether or not to reject the null

hypothesisIn this case, there is no hypothesis/null hypothesis to retain or reject

Conclusion – Pitfalls

Internal Validity was hindered due to multiple biases (as previously mentioned)

External ValidityTools and types of materials were not clearly statedStudy took place in Korea

Cultural differences may naturally occur

“distress felt by affected patients tends to be greater in Asian countries, where the feet are often displayed indoors”

This may have skewed Satisfaction and Willingness survey

SUMMARY

Summary

Future studies should be performed to overcome limitations due to: Biases (Recall bias, Selection biases, and Researcher bias)

Prospective study would result in less confounding variables

Could not be generalized to all clinical settings Some aspects of this study can be used for informative purposes, pre-operational

counseling, etc. Ex. More rapid healing time in bone graft, longer lengthening in the distraction method,

higher satisfaction scores with the gradual distraction with osteotome

Overall, without a hypothesis and without clear evidence supporting this study’s findings, it is hard to find this paper to be reliable

Resources

Baek, G., & Chung, M. (1998). The treatment of congenital brachymetatarsia by one-stage lengthening. The Journal Of Bone And Joint Surgery, 1040-1044.

Choi, I., Chung, M., Baek, G., Cho, T., & Chung, C. (n.d.). Metatarsal Lengthening in Congenital Brachymetatarsia: One-Stage Lengthening Versus Lengthening by Callotasis. Journal of Pediatric Orthopaedics, 660-660.

Ferrandez, L., Yubero, J., Usabiaga, J., & Ramos, L. (1993). Congenital Brachymetatarsia: Three Cases. Foot & Ankle International, 529-533.

Pasternack, W. (n.d.). Brachymetatarsia. A unique surgical approach. Journal of the American Podiatric Medical Association, 415-418

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Thank you